Java/Data Type/Primitive Data Type
Содержание
- 1 A mutable boolean wrapper.
- 2 A mutable byte wrapper.
- 3 A mutable double wrapper.
- 4 A mutable float wrapper.
- 5 A mutable int wrapper.
- 6 A mutable long wrapper.
- 7 A mutable short wrapper.
- 8 Arithmetic Demo
- 9 Built in types
- 10 Convert Java Integer object to Numeric primitive types
- 11 Convert Java String to Integer object
- 12 Convert primitive back and forth
- 13 Convert the given array (which may be a primitive array) to an object array
- 14 Create an Integer object
- 15 Data Type Print Test
- 16 Demonstrates the ++ and -- operators
- 17 Demonstrates the mathematical operators.
- 18 Java lets you overflow
- 19 Java Type Helper
- 20 Literals
- 21 Max Variable Length Demo
- 22 Parse Number
- 23 Primitive utilities
- 24 Relational Demo
- 25 Returns a default value if the object passed is null
- 26 Shows default initial values
- 27 Tests all the operators on all the primitive data types
- 28 Use Integer constructor to convert int primitive type to Integer object.
A mutable boolean wrapper.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.Serializable;
/**
* A mutable <code>boolean</code> wrapper.
*
* @see Boolean
* @since 2.2
* @author Apache Software Foundation
* @version $Id: MutableBoolean.java 491052 2006-12-29 17:16:37Z scolebourne $
*/
public class MutableBoolean implements Mutable, Serializable, Comparable {
/**
* Required for serialization support.
*
* @see java.io.Serializable
*/
private static final long serialVersionUID = -4830728138360036487L;
/** The mutable value. */
private boolean value;
/**
* Constructs a new MutableBoolean with the default value of false.
*/
public MutableBoolean() {
super();
}
/**
* Constructs a new MutableBoolean with the specified value.
*
* @param value
* a value.
*/
public MutableBoolean(boolean value) {
super();
this.value = value;
}
/**
* Constructs a new MutableBoolean with the specified value.
*
* @param value
* a value.
* @throws NullPointerException
* if the object is null
*/
public MutableBoolean(Boolean value) {
super();
this.value = value.booleanValue();
}
// -----------------------------------------------------------------------
/**
* Returns the value of this MutableBoolean as a boolean.
*
* @return the boolean value represented by this object.
*/
public boolean booleanValue() {
return value;
}
/**
* Compares this mutable to another in ascending order.
*
* @param obj
* the mutable to compare to
* @return zero if this object represents the same boolean value as the argument; a positive value if this object
* represents true and the argument represents false; and a negative value if this object represents false
* and the argument represents true
* @throws ClassCastException
* if the argument is not a MutableInt
*/
public int compareTo(Object obj) {
MutableBoolean other = (MutableBoolean) obj;
boolean anotherVal = other.value;
return value == anotherVal ? 0 : (value ? 1 : -1);
}
// -----------------------------------------------------------------------
/**
* Compares this object to the specified object. The result is <code>true</code> if and only if the argument is
* not <code>null</code> and is an <code>MutableBoolean</code> object that contains the same
* <code>boolean</code> value as this object.
*
* @param obj
* the object to compare with.
* @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
*/
public boolean equals(Object obj) {
if (obj instanceof MutableBoolean) {
return value == ((MutableBoolean) obj).booleanValue();
}
return false;
}
// -----------------------------------------------------------------------
/**
* Gets the value as a Boolean instance.
*
* @return the value as a Boolean
*/
public Object getValue() {
return this.value;
}
/**
* Returns a suitable hashcode for this mutable.
*
* @return the integer <code>1231</code> if this object represents <code>true</code>; returns the integer
* <code>1237</code> if this object represents <code>false</code>.
*/
public int hashCode() {
return value ? Boolean.TRUE.hashCode() : Boolean.FALSE.hashCode();
}
/**
* Sets the value.
*
* @param value
* the value to set
*/
public void setValue(boolean value) {
this.value = value;
}
/**
* Sets the value from any Boolean instance.
*
* @param value
* the value to set
* @throws NullPointerException
* if the object is null
* @throws ClassCastException
* if the type is not a {@link Boolean}
*/
public void setValue(Object value) {
setValue(((Boolean) value).booleanValue());
}
/**
* Returns the String value of this mutable.
*
* @return the mutable value as a string
*/
public String toString() {
return String.valueOf(value);
}
}
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Provides mutable access to a value.
* <p>
* <code>Mutable</code> is used as a generic interface to the implementations in this package.
* <p>
* A typical use case would be to enable a primitive or string to be passed to a method and allow that method to
* effectively change the value of the primitive/string. Another use case is to store a frequently changing primitive in
* a collection (for example a total in a map) without needing to create new Integer/Long wrapper objects.
*
* @author Matthew Hawthorne
* @since 2.1
* @version $Id: Mutable.java 618693 2008-02-05 16:33:29Z sebb $
*/
interface Mutable {
/**
* Gets the value of this mutable.
*
* @return the stored value
*/
Object getValue();
/**
* Sets the value of this mutable.
*
* @param value
* the value to store
* @throws NullPointerException
* if the object is null and null is invalid
* @throws ClassCastException
* if the type is invalid
*/
void setValue(Object value);
}
A mutable byte wrapper.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Revised from commons lang from Apache
/**
* A mutable <code>byte</code> wrapper.
*
* @see Byte
* @since 2.1
* @version $Id: MutableByte.java 618693 2008-02-05 16:33:29Z sebb $
*/
public class MutableByte extends Number implements Comparable, Mutable {
/**
* Required for serialization support.
*
* @see java.io.Serializable
*/
private static final long serialVersionUID = -1585823265L;
/** The mutable value. */
private byte value;
/**
* Constructs a new MutableByte with the default value of zero.
*/
public MutableByte() {
super();
}
/**
* Constructs a new MutableByte with the specified value.
*
* @param value
* a value.
*/
public MutableByte(byte value) {
super();
this.value = value;
}
/**
* Constructs a new MutableByte with the specified value.
*
* @param value
* a value.
* @throws NullPointerException
* if the object is null
*/
public MutableByte(Number value) {
super();
this.value = value.byteValue();
}
//-----------------------------------------------------------------------
/**
* Gets the value as a Byte instance.
*
* @return the value as a Byte
*/
public Object getValue() {
return new Byte(this.value);
}
/**
* Sets the value.
*
* @param value
* the value to set
*/
public void setValue(byte value) {
this.value = value;
}
/**
* Sets the value from any Number instance.
*
* @param value
* the value to set
* @throws NullPointerException
* if the object is null
* @throws ClassCastException
* if the type is not a {@link Number}
*/
public void setValue(Object value) {
setValue(((Number) value).byteValue());
}
//-----------------------------------------------------------------------
// shortValue relies on Number implementation
/**
* Returns the value of this MutableByte as a byte.
*
* @return the numeric value represented by this object after conversion to type byte.
*/
public byte byteValue() {
return value;
}
/**
* Returns the value of this MutableByte as a int.
*
* @return the numeric value represented by this object after conversion to type int.
*/
public int intValue() {
return value;
}
/**
* Returns the value of this MutableByte as a long.
*
* @return the numeric value represented by this object after conversion to type long.
*/
public long longValue() {
return value;
}
/**
* Returns the value of this MutableByte as a float.
*
* @return the numeric value represented by this object after conversion to type float.
*/
public float floatValue() {
return value;
}
/**
* Returns the value of this MutableByte as a double.
*
* @return the numeric value represented by this object after conversion to type double.
*/
public double doubleValue() {
return value;
}
//-----------------------------------------------------------------------
/**
* Gets this mutable as an instance of Byte.
*
* @return a Byte instance containing the value from this mutable
*/
public Byte toByte() {
return new Byte(byteValue());
}
//-----------------------------------------------------------------------
/**
* Increments the value.
*
* @since Commons Lang 2.2
*/
public void increment() {
value++;
}
/**
* Decrements the value.
*
* @since Commons Lang 2.2
*/
public void decrement() {
value--;
}
//-----------------------------------------------------------------------
/**
* Adds a value.
*
* @param operand
* the value to add
*
* @since Commons Lang 2.2
*/
public void add(byte operand) {
this.value += operand;
}
/**
* Adds a value.
*
* @param operand
* the value to add
* @throws NullPointerException
* if the object is null
*
* @since Commons Lang 2.2
*/
public void add(Number operand) {
this.value += operand.byteValue();
}
/**
* Subtracts a value.
*
* @param operand
* the value to add
*
* @since Commons Lang 2.2
*/
public void subtract(byte operand) {
this.value -= operand;
}
/**
* Subtracts a value.
*
* @param operand
* the value to add
* @throws NullPointerException
* if the object is null
*
* @since Commons Lang 2.2
*/
public void subtract(Number operand) {
this.value -= operand.byteValue();
}
//-----------------------------------------------------------------------
/**
* Compares this object against the specified object. The result is <code>true</code> if and only if the argument
* is not <code>null</code> and is a <code>MutableByte</code> object that contains the same <code>byte</code>
* value as this object.
*
* @param obj
* the object to compare with.
* @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
*/
public boolean equals(Object obj) {
if (obj instanceof MutableByte) {
return value == ((MutableByte) obj).byteValue();
}
return false;
}
/**
* Returns a suitable hashcode for this mutable.
*
* @return a suitable hashcode
*/
public int hashCode() {
return value;
}
/**
* Compares this mutable to another in ascending order.
*
* @param obj
* the mutable to compare to
* @return negative if this is less, zero if equal, positive if greater
* @throws ClassCastException if the argument is not a MutableByte
*/
public int compareTo(Object obj) {
MutableByte other = (MutableByte) obj;
byte anotherVal = other.value;
return value < anotherVal ? -1 : (value == anotherVal ? 0 : 1);
}
/**
* Returns the String value of this mutable.
*
* @return the mutable value as a string
*/
public String toString() {
return String.valueOf(value);
}
}
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Provides mutable access to a value.
* <p>
* <code>Mutable</code> is used as a generic interface to the implementations in this package.
* <p>
* A typical use case would be to enable a primitive or string to be passed to a method and allow that method to
* effectively change the value of the primitive/string. Another use case is to store a frequently changing primitive in
* a collection (for example a total in a map) without needing to create new Integer/Long wrapper objects.
*
* @author Matthew Hawthorne
* @since 2.1
* @version $Id: Mutable.java 618693 2008-02-05 16:33:29Z sebb $
*/
interface Mutable {
/**
* Gets the value of this mutable.
*
* @return the stored value
*/
Object getValue();
/**
* Sets the value of this mutable.
*
* @param value
* the value to store
* @throws NullPointerException
* if the object is null and null is invalid
* @throws ClassCastException
* if the type is invalid
*/
void setValue(Object value);
}
A mutable double wrapper.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* A mutable <code>double</code> wrapper.
*
* @see Double
* @since 2.1
* @version $Id: MutableDouble.java 618693 2008-02-05 16:33:29Z sebb $
*/
public class MutableDouble extends Number implements Comparable, Mutable {
/**
* Required for serialization support.
*
* @see java.io.Serializable
*/
private static final long serialVersionUID = 1587163916L;
/** The mutable value. */
private double value;
/**
* Constructs a new MutableDouble with the default value of zero.
*/
public MutableDouble() {
super();
}
/**
* Constructs a new MutableDouble with the specified value.
*
* @param value
* a value.
*/
public MutableDouble(double value) {
super();
this.value = value;
}
/**
* Constructs a new MutableDouble with the specified value.
*
* @param value
* a value.
* @throws NullPointerException
* if the object is null
*/
public MutableDouble(Number value) {
super();
this.value = value.doubleValue();
}
// -----------------------------------------------------------------------
/**
* Gets the value as a Double instance.
*
* @return the value as a Double
*/
public Object getValue() {
return new Double(this.value);
}
/**
* Sets the value.
*
* @param value
* the value to set
*/
public void setValue(double value) {
this.value = value;
}
/**
* Sets the value from any Number instance.
*
* @param value
* the value to set
* @throws NullPointerException
* if the object is null
* @throws ClassCastException
* if the type is not a {@link Number}
*/
public void setValue(Object value) {
setValue(((Number) value).doubleValue());
}
// -----------------------------------------------------------------------
// shortValue and bytValue rely on Number implementation
/**
* Returns the value of this MutableDouble as a int.
*
* @return the numeric value represented by this object after conversion to
* type int.
*/
public int intValue() {
return (int) value;
}
/**
* Returns the value of this MutableDouble as a long.
*
* @return the numeric value represented by this object after conversion to
* type long.
*/
public long longValue() {
return (long) value;
}
/**
* Returns the value of this MutableDouble as a float.
*
* @return the numeric value represented by this object after conversion to
* type float.
*/
public float floatValue() {
return (float) value;
}
/**
* Returns the value of this MutableDouble as a double.
*
* @return the numeric value represented by this object after conversion to
* type double.
*/
public double doubleValue() {
return value;
}
/**
* Checks whether the double value is the special NaN value.
*
* @return true if NaN
*/
public boolean isNaN() {
return Double.isNaN(value);
}
/**
* Checks whether the double value is infinite.
*
* @return true if infinite
*/
public boolean isInfinite() {
return Double.isInfinite(value);
}
// -----------------------------------------------------------------------
/**
* Gets this mutable as an instance of Double.
*
* @return a Double instance containing the value from this mutable
*/
public Double toDouble() {
return new Double(doubleValue());
}
// -----------------------------------------------------------------------
/**
* Increments the value.
*
* @since Commons Lang 2.2
*/
public void increment() {
value++;
}
/**
* Decrements the value.
*
* @since Commons Lang 2.2
*/
public void decrement() {
value--;
}
// -----------------------------------------------------------------------
/**
* Adds a value.
*
* @param operand
* the value to add
*
* @since Commons Lang 2.2
*/
public void add(double operand) {
this.value += operand;
}
/**
* Adds a value.
*
* @param operand
* the value to add
* @throws NullPointerException
* if the object is null
*
* @since Commons Lang 2.2
*/
public void add(Number operand) {
this.value += operand.doubleValue();
}
/**
* Subtracts a value.
*
* @param operand
* the value to add
*
* @since Commons Lang 2.2
*/
public void subtract(double operand) {
this.value -= operand;
}
/**
* Subtracts a value.
*
* @param operand
* the value to add
* @throws NullPointerException
* if the object is null
*
* @since Commons Lang 2.2
*/
public void subtract(Number operand) {
this.value -= operand.doubleValue();
}
// -----------------------------------------------------------------------
/**
* Compares this object against the specified object. The result is
* <code>true</code> if and only if the argument is not <code>null</code>
* and is a <code>Double</code> object that represents a double that has the
* identical bit pattern to the bit pattern of the double represented by this
* object. For this purpose, two <code>double</code> values are considered
* to be the same if and only if the method
* {@link Double#doubleToLongBits(double)}returns the same long value when
* applied to each.
* <p>
* Note that in most cases, for two instances of class <code>Double</code>,<code>d1</code>
* and <code>d2</code>, the value of <code>d1.equals(d2)</code> is
* <code>true</code> if and only if <blockquote>
*
* <pre>
* d1.doubleValue() == d2.doubleValue()
* </pre>
*
* </blockquote>
* <p>
* also has the value <code>true</code>. However, there are two exceptions:
* <ul>
* <li>If <code>d1</code> and <code>d2</code> both represent
* <code>Double.NaN</code>, then the <code>equals</code> method returns
* <code>true</code>, even though <code>Double.NaN==Double.NaN</code> has
* the value <code>false</code>.
* <li>If <code>d1</code> represents <code>+0.0</code> while
* <code>d2</code> represents <code>-0.0</code>, or vice versa, the
* <code>equal</code> test has the value <code>false</code>, even though
* <code>+0.0==-0.0</code> has the value <code>true</code>. This allows
* hashtables to operate properly.
* </ul>
*
* @param obj
* the object to compare with.
* @return <code>true</code> if the objects are the same; <code>false</code>
* otherwise.
*/
public boolean equals(Object obj) {
return (obj instanceof MutableDouble)
&& (Double.doubleToLongBits(((MutableDouble) obj).value) == Double.doubleToLongBits(value));
}
/**
* Returns a suitable hashcode for this mutable.
*
* @return a suitable hashcode
*/
public int hashCode() {
long bits = Double.doubleToLongBits(value);
return (int) (bits ^ (bits >>> 32));
}
/**
* Compares this mutable to another in ascending order.
*
* @param obj
* the mutable to compare to
* @return negative if this is less, zero if equal, positive if greater
* @throws ClassCastException
* if the argument is not a MutableDouble
*/
public int compareTo(Object obj) {
MutableDouble other = (MutableDouble) obj;
double anotherVal = other.value;
return compare(value, anotherVal);
}
/**
* Returns the String value of this mutable.
*
* @return the mutable value as a string
*/
public String toString() {
return String.valueOf(value);
}
protected int compare(Object o1, Object o2) {
if (o1 == null) {
if (o2 == null) {
return 0;
} else {
return -((Comparable) o2).rupareTo(o1);
}
} else {
return ((Comparable) o1).rupareTo(o2);
}
}
}
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with this
* work for additional information regarding copyright ownership. The ASF
* licenses this file to You under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
/**
* Provides mutable access to a value.
* <p>
* <code>Mutable</code> is used as a generic interface to the implementations
* in this package.
* <p>
* A typical use case would be to enable a primitive or string to be passed to a
* method and allow that method to effectively change the value of the
* primitive/string. Another use case is to store a frequently changing
* primitive in a collection (for example a total in a map) without needing to
* create new Integer/Long wrapper objects.
*
* @author Matthew Hawthorne
* @since 2.1
* @version $Id: Mutable.java 618693 2008-02-05 16:33:29Z sebb $
*/
interface Mutable {
/**
* Gets the value of this mutable.
*
* @return the stored value
*/
Object getValue();
/**
* Sets the value of this mutable.
*
* @param value
* the value to store
* @throws NullPointerException
* if the object is null and null is invalid
* @throws ClassCastException
* if the type is invalid
*/
void setValue(Object value);
}
A mutable float wrapper.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//Revised from commons lang Apache
/**
* A mutable <code>float</code> wrapper.
*
* @see Float
* @since 2.1
* @version $Id: MutableFloat.java 618693 2008-02-05 16:33:29Z sebb $
*/
public class MutableFloat extends Number implements Comparable, Mutable {
/**
* Required for serialization support.
*
* @see java.io.Serializable
*/
private static final long serialVersionUID = 5787169186L;
/** The mutable value. */
private float value;
/**
* Constructs a new MutableFloat with the default value of zero.
*/
public MutableFloat() {
super();
}
/**
* Constructs a new MutableFloat with the specified value.
*
* @param value
* a value.
*/
public MutableFloat(float value) {
super();
this.value = value;
}
/**
* Constructs a new MutableFloat with the specified value.
*
* @param value
* a value.
* @throws NullPointerException
* if the object is null
*/
public MutableFloat(Number value) {
super();
this.value = value.floatValue();
}
//-----------------------------------------------------------------------
/**
* Gets the value as a Float instance.
*
* @return the value as a Float
*/
public Object getValue() {
return new Float(this.value);
}
/**
* Sets the value.
*
* @param value
* the value to set
*/
public void setValue(float value) {
this.value = value;
}
/**
* Sets the value from any Number instance.
*
* @param value
* the value to set
* @throws NullPointerException
* if the object is null
* @throws ClassCastException
* if the type is not a {@link Number}
*/
public void setValue(Object value) {
setValue(((Number) value).floatValue());
}
//-----------------------------------------------------------------------
/**
* Increments the value.
*
* @since Commons Lang 2.2
*/
public void increment() {
value++;
}
/**
* Decrements the value.
*
* @since Commons Lang 2.2
*/
public void decrement() {
value--;
}
//-----------------------------------------------------------------------
/**
* Adds a value.
*
* @param operand
* the value to add
*
* @since Commons Lang 2.2
*/
public void add(float operand) {
this.value += operand;
}
/**
* Adds a value.
*
* @param operand
* the value to add
* @throws NullPointerException
* if the object is null
*
* @since Commons Lang 2.2
*/
public void add(Number operand) {
this.value += operand.floatValue();
}
/**
* Subtracts a value.
*
* @param operand
* the value to add
*
* @since Commons Lang 2.2
*/
public void subtract(float operand) {
this.value -= operand;
}
/**
* Subtracts a value.
*
* @param operand
* the value to add
* @throws NullPointerException
* if the object is null
*
* @since Commons Lang 2.2
*/
public void subtract(Number operand) {
this.value -= operand.floatValue();
}
//-----------------------------------------------------------------------
// shortValue and bytValue rely on Number implementation
/**
* Returns the value of this MutableFloat as a int.
*
* @return the numeric value represented by this object after conversion to type int.
*/
public int intValue() {
return (int) value;
}
/**
* Returns the value of this MutableFloat as a long.
*
* @return the numeric value represented by this object after conversion to type long.
*/
public long longValue() {
return (long) value;
}
/**
* Returns the value of this MutableFloat as a float.
*
* @return the numeric value represented by this object after conversion to type float.
*/
public float floatValue() {
return value;
}
/**
* Returns the value of this MutableFloat as a double.
*
* @return the numeric value represented by this object after conversion to type double.
*/
public double doubleValue() {
return value;
}
/**
* Checks whether the float value is the special NaN value.
*
* @return true if NaN
*/
public boolean isNaN() {
return Float.isNaN(value);
}
/**
* Checks whether the float value is infinite.
*
* @return true if infinite
*/
public boolean isInfinite() {
return Float.isInfinite(value);
}
//-----------------------------------------------------------------------
/**
* Gets this mutable as an instance of Float.
*
* @return a Float instance containing the value from this mutable
*/
public Float toFloat() {
return new Float(floatValue());
}
//-----------------------------------------------------------------------
/**
* Compares this object against some other object. The result is <code>true</code> if and only if the argument is
* not <code>null</code> and is a <code>Float</code> object that represents a <code>float</code> that has the
* identical bit pattern to the bit pattern of the <code>float</code> represented by this object. For this
* purpose, two float values are considered to be the same if and only if the method
* {@link Float#floatToIntBits(float)}returns the same int value when applied to each.
* <p>
* Note that in most cases, for two instances of class <code>Float</code>,<code>f1</code> and <code>f2</code>,
* the value of <code>f1.equals(f2)</code> is <code>true</code> if and only if <blockquote>
*
* <pre>
* f1.floatValue() == f2.floatValue()
* </pre>
*
* </blockquote>
* <p>
* also has the value <code>true</code>. However, there are two exceptions:
* <ul>
* <li>If <code>f1</code> and <code>f2</code> both represent <code>Float.NaN</code>, then the
* <code>equals</code> method returns <code>true</code>, even though <code>Float.NaN==Float.NaN</code> has
* the value <code>false</code>.
* <li>If <code>f1</code> represents <code>+0.0f</code> while <code>f2</code> represents <code>-0.0f</code>,
* or vice versa, the <code>equal</code> test has the value <code>false</code>, even though
* <code>0.0f==-0.0f</code> has the value <code>true</code>.
* </ul>
* This definition allows hashtables to operate properly.
*
* @param obj
* the object to be compared
* @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
* @see java.lang.Float#floatToIntBits(float)
*/
public boolean equals(Object obj) {
return (obj instanceof MutableFloat)
&& (Float.floatToIntBits(((MutableFloat) obj).value) == Float.floatToIntBits(value));
}
//-----------------------------------------------------------------------
/**
* Returns a suitable hashcode for this mutable.
*
* @return a suitable hashcode
*/
public int hashCode() {
return Float.floatToIntBits(value);
}
/**
* Compares this mutable to another in ascending order.
*
* @param obj
* the mutable to compare to
* @return negative if this is less, zero if equal, positive if greater
*/
public int compareTo(Object obj) {
MutableFloat other = (MutableFloat) obj;
float anotherVal = other.value;
return compare(value, anotherVal);
}
protected int compare(Object o1, Object o2) {
if (o1 == null) {
if (o2 == null) {
return 0;
} else {
return -((Comparable) o2).rupareTo(o1);
}
} else {
return ((Comparable) o1).rupareTo(o2);
}
}
/**
* Returns the String value of this mutable.
*
* @return the mutable value as a string
*/
public String toString() {
return String.valueOf(value);
}
}
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with this
* work for additional information regarding copyright ownership. The ASF
* licenses this file to You under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
/**
* Provides mutable access to a value.
* <p>
* <code>Mutable</code> is used as a generic interface to the implementations
* in this package.
* <p>
* A typical use case would be to enable a primitive or string to be passed to a
* method and allow that method to effectively change the value of the
* primitive/string. Another use case is to store a frequently changing
* primitive in a collection (for example a total in a map) without needing to
* create new Integer/Long wrapper objects.
*
* @author Matthew Hawthorne
* @since 2.1
* @version $Id: Mutable.java 618693 2008-02-05 16:33:29Z sebb $
*/
interface Mutable {
/**
* Gets the value of this mutable.
*
* @return the stored value
*/
Object getValue();
/**
* Sets the value of this mutable.
*
* @param value
* the value to store
* @throws NullPointerException
* if the object is null and null is invalid
* @throws ClassCastException
* if the type is invalid
*/
void setValue(Object value);
}
A mutable int wrapper.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Rwevised from commons lang Apache
/**
* A mutable <code>int</code> wrapper.
*
* @see Integer
* @since 2.1
* @version $Id: MutableInt.java 437554 2006-08-28 06:21:41Z bayard $
*/
public class MutableInt extends Number implements Comparable, Mutable {
/**
* Required for serialization support.
*
* @see java.io.Serializable
*/
private static final long serialVersionUID = 512176391864L;
/** The mutable value. */
private int value;
/**
* Constructs a new MutableInt with the default value of zero.
*/
public MutableInt() {
super();
}
/**
* Constructs a new MutableInt with the specified value.
*
* @param value
* a value.
*/
public MutableInt(int value) {
super();
this.value = value;
}
/**
* Constructs a new MutableInt with the specified value.
*
* @param value
* a value.
* @throws NullPointerException
* if the object is null
*/
public MutableInt(Number value) {
super();
this.value = value.intValue();
}
//-----------------------------------------------------------------------
/**
* Gets the value as a Integer instance.
*
* @return the value as a Integer
*/
public Object getValue() {
return new Integer(this.value);
}
/**
* Sets the value.
*
* @param value
* the value to set
*/
public void setValue(int value) {
this.value = value;
}
/**
* Sets the value from any Number instance.
*
* @param value
* the value to set
* @throws NullPointerException
* if the object is null
* @throws ClassCastException
* if the type is not a {@link Number}
*/
public void setValue(Object value) {
setValue(((Number) value).intValue());
}
//-----------------------------------------------------------------------
/**
* Increments the value.
*
* @since Commons Lang 2.2
*/
public void increment() {
value++;
}
/**
* Decrements the value.
*
* @since Commons Lang 2.2
*/
public void decrement() {
value--;
}
//-----------------------------------------------------------------------
/**
* Adds a value.
*
* @param operand
* the value to add
*
* @since Commons Lang 2.2
*/
public void add(int operand) {
this.value += operand;
}
/**
* Adds a value.
*
* @param operand
* the value to add
* @throws NullPointerException
* if the object is null
*
* @since Commons Lang 2.2
*/
public void add(Number operand) {
this.value += operand.intValue();
}
/**
* Subtracts a value.
*
* @param operand
* the value to add
*
* @since Commons Lang 2.2
*/
public void subtract(int operand) {
this.value -= operand;
}
/**
* Subtracts a value.
*
* @param operand
* the value to add
* @throws NullPointerException
* if the object is null
*
* @since Commons Lang 2.2
*/
public void subtract(Number operand) {
this.value -= operand.intValue();
}
//-----------------------------------------------------------------------
// shortValue and bytValue rely on Number implementation
/**
* Returns the value of this MutableInt as a int.
*
* @return the numeric value represented by this object after conversion to type int.
*/
public int intValue() {
return value;
}
/**
* Returns the value of this MutableInt as a long.
*
* @return the numeric value represented by this object after conversion to type long.
*/
public long longValue() {
return value;
}
/**
* Returns the value of this MutableInt as a float.
*
* @return the numeric value represented by this object after conversion to type float.
*/
public float floatValue() {
return value;
}
/**
* Returns the value of this MutableInt as a double.
*
* @return the numeric value represented by this object after conversion to type double.
*/
public double doubleValue() {
return value;
}
//-----------------------------------------------------------------------
/**
* Gets this mutable as an instance of Integer.
*
* @return a Integer instance containing the value from this mutable
*/
public Integer toInteger() {
return new Integer(intValue());
}
//-----------------------------------------------------------------------
/**
* Compares this object to the specified object. The result is <code>true</code> if and only if the argument is
* not <code>null</code> and is an <code>MutableInt</code> object that contains the same <code>int</code> value
* as this object.
*
* @param obj
* the object to compare with.
* @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
*/
public boolean equals(Object obj) {
if (obj instanceof MutableInt) {
return value == ((MutableInt) obj).intValue();
}
return false;
}
/**
* Returns a suitable hashcode for this mutable.
*
* @return a suitable hashcode
*/
public int hashCode() {
return value;
}
/**
* Compares this mutable to another in ascending order.
*
* @param obj
* the mutable to compare to
* @return negative if this is less, zero if equal, positive if greater
* @throws ClassCastException if the argument is not a MutableInt
*/
public int compareTo(Object obj) {
MutableInt other = (MutableInt) obj;
int anotherVal = other.value;
return value < anotherVal ? -1 : (value == anotherVal ? 0 : 1);
}
/**
* Returns the String value of this mutable.
*
* @return the mutable value as a string
*/
public String toString() {
return String.valueOf(value);
}
}
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with this
* work for additional information regarding copyright ownership. The ASF
* licenses this file to You under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
/**
* Provides mutable access to a value.
* <p>
* <code>Mutable</code> is used as a generic interface to the implementations
* in this package.
* <p>
* A typical use case would be to enable a primitive or string to be passed to a
* method and allow that method to effectively change the value of the
* primitive/string. Another use case is to store a frequently changing
* primitive in a collection (for example a total in a map) without needing to
* create new Integer/Long wrapper objects.
*
* @author Matthew Hawthorne
* @since 2.1
* @version $Id: Mutable.java 618693 2008-02-05 16:33:29Z sebb $
*/
interface Mutable {
/**
* Gets the value of this mutable.
*
* @return the stored value
*/
Object getValue();
/**
* Sets the value of this mutable.
*
* @param value
* the value to store
* @throws NullPointerException
* if the object is null and null is invalid
* @throws ClassCastException
* if the type is invalid
*/
void setValue(Object value);
}
A mutable long wrapper.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Revised from commons lang Apache
/**
* A mutable <code>long</code> wrapper.
*
* @see Long
* @since 2.1
* @version $Id: MutableLong.java 618693 2008-02-05 16:33:29Z sebb $
*/
public class MutableLong extends Number implements Comparable, Mutable {
/**
* Required for serialization support.
*
* @see java.io.Serializable
*/
private static final long serialVersionUID = 62986528375L;
/** The mutable value. */
private long value;
/**
* Constructs a new MutableLong with the default value of zero.
*/
public MutableLong() {
super();
}
/**
* Constructs a new MutableLong with the specified value.
*
* @param value
* a value.
*/
public MutableLong(long value) {
super();
this.value = value;
}
/**
* Constructs a new MutableLong with the specified value.
*
* @param value
* a value.
* @throws NullPointerException
* if the object is null
*/
public MutableLong(Number value) {
super();
this.value = value.longValue();
}
//-----------------------------------------------------------------------
/**
* Gets the value as a Long instance.
*
* @return the value as a Long
*/
public Object getValue() {
return new Long(this.value);
}
/**
* Sets the value.
*
* @param value
* the value to set
*/
public void setValue(long value) {
this.value = value;
}
/**
* Sets the value from any Number instance.
*
* @param value
* the value to set
* @throws NullPointerException
* if the object is null
* @throws ClassCastException
* if the type is not a {@link Number}
*/
public void setValue(Object value) {
setValue(((Number) value).longValue());
}
//-----------------------------------------------------------------------
/**
* Increments the value.
*
* @since Commons Lang 2.2
*/
public void increment() {
value++;
}
/**
* Decrements the value.
*
* @since Commons Lang 2.2
*/
public void decrement() {
value--;
}
//-----------------------------------------------------------------------
/**
* Adds a value.
*
* @param operand
* the value to add
*
* @since Commons Lang 2.2
*/
public void add(long operand) {
this.value += operand;
}
/**
* Adds a value.
*
* @param operand
* the value to add
* @throws NullPointerException
* if the object is null
*
* @since Commons Lang 2.2
*/
public void add(Number operand) {
this.value += operand.longValue();
}
/**
* Subtracts a value.
*
* @param operand
* the value to add
*
* @since Commons Lang 2.2
*/
public void subtract(long operand) {
this.value -= operand;
}
/**
* Subtracts a value.
*
* @param operand
* the value to add
* @throws NullPointerException
* if the object is null
*
* @since Commons Lang 2.2
*/
public void subtract(Number operand) {
this.value -= operand.longValue();
}
//-----------------------------------------------------------------------
// shortValue and bytValue rely on Number implementation
/**
* Returns the value of this MutableLong as a int.
*
* @return the numeric value represented by this object after conversion to type int.
*/
public int intValue() {
return (int) value;
}
/**
* Returns the value of this MutableLong as a long.
*
* @return the numeric value represented by this object after conversion to type long.
*/
public long longValue() {
return value;
}
/**
* Returns the value of this MutableLong as a float.
*
* @return the numeric value represented by this object after conversion to type float.
*/
public float floatValue() {
return value;
}
/**
* Returns the value of this MutableLong as a double.
*
* @return the numeric value represented by this object after conversion to type double.
*/
public double doubleValue() {
return value;
}
//-----------------------------------------------------------------------
/**
* Gets this mutable as an instance of Long.
*
* @return a Long instance containing the value from this mutable
*/
public Long toLong() {
return new Long(longValue());
}
//-----------------------------------------------------------------------
/**
* Compares this object against the specified object. The result is <code>true</code> if and only if the argument
* is not <code>null</code> and is a <code>MutableLong</code> object that contains the same <code>long</code>
* value as this object.
*
* @param obj
* the object to compare with.
* @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
*/
public boolean equals(Object obj) {
if (obj instanceof MutableLong) {
return value == ((MutableLong) obj).longValue();
}
return false;
}
/**
* Returns a suitable hashcode for this mutable.
*
* @return a suitable hashcode
*/
public int hashCode() {
return (int) (value ^ (value >>> 32));
}
/**
* Compares this mutable to another in ascending order.
*
* @param obj
* the mutable to compare to
* @return negative if this is less, zero if equal, positive if greater
* @throws ClassCastException if the argument is not a MutableLong
*/
public int compareTo(Object obj) {
MutableLong other = (MutableLong) obj;
long anotherVal = other.value;
return value < anotherVal ? -1 : (value == anotherVal ? 0 : 1);
}
/**
* Returns the String value of this mutable.
*
* @return the mutable value as a string
*/
public String toString() {
return String.valueOf(value);
}
}
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with this
* work for additional information regarding copyright ownership. The ASF
* licenses this file to You under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
/**
* Provides mutable access to a value.
* <p>
* <code>Mutable</code> is used as a generic interface to the implementations
* in this package.
* <p>
* A typical use case would be to enable a primitive or string to be passed to a
* method and allow that method to effectively change the value of the
* primitive/string. Another use case is to store a frequently changing
* primitive in a collection (for example a total in a map) without needing to
* create new Integer/Long wrapper objects.
*
* @author Matthew Hawthorne
* @since 2.1
* @version $Id: Mutable.java 618693 2008-02-05 16:33:29Z sebb $
*/
interface Mutable {
/**
* Gets the value of this mutable.
*
* @return the stored value
*/
Object getValue();
/**
* Sets the value of this mutable.
*
* @param value
* the value to store
* @throws NullPointerException
* if the object is null and null is invalid
* @throws ClassCastException
* if the type is invalid
*/
void setValue(Object value);
}
A mutable short wrapper.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Revised from commons math Apache
/**
* A mutable <code>short</code> wrapper.
*
* @see Short
* @since 2.1
* @version $Id: MutableShort.java 618693 2008-02-05 16:33:29Z sebb $
*/
public class MutableShort extends Number implements Comparable, Mutable {
/**
* Required for serialization support.
*
* @see java.io.Serializable
*/
private static final long serialVersionUID = -2135791679L;
/** The mutable value. */
private short value;
/**
* Constructs a new MutableShort with the default value of zero.
*/
public MutableShort() {
super();
}
/**
* Constructs a new MutableShort with the specified value.
*
* @param value
* a value.
*/
public MutableShort(short value) {
super();
this.value = value;
}
/**
* Constructs a new MutableShort with the specified value.
*
* @param value
* a value.
* @throws NullPointerException
* if the object is null
*/
public MutableShort(Number value) {
super();
this.value = value.shortValue();
}
//-----------------------------------------------------------------------
/**
* Gets the value as a Short instance.
*
* @return the value as a Short
*/
public Object getValue() {
return new Short(this.value);
}
/**
* Sets the value.
*
* @param value
* the value to set
*/
public void setValue(short value) {
this.value = value;
}
/**
* Sets the value from any Number instance.
*
* @param value
* the value to set
* @throws NullPointerException
* if the object is null
* @throws ClassCastException
* if the type is not a {@link Number}
*/
public void setValue(Object value) {
setValue(((Number) value).shortValue());
}
//-----------------------------------------------------------------------
/**
* Increments the value.
*
* @since Commons Lang 2.2
*/
public void increment() {
value++;
}
/**
* Decrements the value.
*
* @since Commons Lang 2.2
*/
public void decrement() {
value--;
}
//-----------------------------------------------------------------------
/**
* Adds a value.
*
* @param operand
* the value to add
*
* @since Commons Lang 2.2
*/
public void add(short operand) {
this.value += operand;
}
/**
* Adds a value.
*
* @param operand
* the value to add
* @throws NullPointerException
* if the object is null
*
* @since Commons Lang 2.2
*/
public void add(Number operand) {
this.value += operand.shortValue();
}
/**
* Subtracts a value.
*
* @param operand
* the value to add
*
* @since Commons Lang 2.2
*/
public void subtract(short operand) {
this.value -= operand;
}
/**
* Subtracts a value.
*
* @param operand
* the value to add
* @throws NullPointerException
* if the object is null
*
* @since Commons Lang 2.2
*/
public void subtract(Number operand) {
this.value -= operand.shortValue();
}
//-----------------------------------------------------------------------
// bytValue relies on Number implementation
/**
* Returns the value of this MutableShort as a short.
*
* @return the numeric value represented by this object after conversion to type short.
*/
public short shortValue() {
return value;
}
/**
* Returns the value of this MutableShort as a int.
*
* @return the numeric value represented by this object after conversion to type int.
*/
public int intValue() {
return value;
}
/**
* Returns the value of this MutableShort as a long.
*
* @return the numeric value represented by this object after conversion to type long.
*/
public long longValue() {
return value;
}
/**
* Returns the value of this MutableShort as a float.
*
* @return the numeric value represented by this object after conversion to type float.
*/
public float floatValue() {
return value;
}
/**
* Returns the value of this MutableShort as a double.
*
* @return the numeric value represented by this object after conversion to type double.
*/
public double doubleValue() {
return value;
}
//-----------------------------------------------------------------------
/**
* Gets this mutable as an instance of Short.
*
* @return a Short instance containing the value from this mutable
*/
public Short toShort() {
return new Short(shortValue());
}
//-----------------------------------------------------------------------
/**
* Compares this object against the specified object. The result is <code>true</code> if and only if the argument
* is not <code>null</code> and is a <code>MutableShort</code> object that contains the same <code>short</code>
* value as this object.
*
* @param obj
* the object to compare with.
* @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
*/
public boolean equals(Object obj) {
if (obj instanceof MutableShort) {
return value == ((MutableShort) obj).shortValue();
}
return false;
}
/**
* Returns a suitable hashcode for this mutable.
*
* @return a suitable hashcode
*/
public int hashCode() {
return value;
}
/**
* Compares this mutable to another in ascending order.
*
* @param obj
* the mutable to compare to
* @return negative if this is less, zero if equal, positive if greater
* @throws ClassCastException if the argument is not a MutableShort
*/
public int compareTo(Object obj) {
MutableShort other = (MutableShort) obj;
short anotherVal = other.value;
return value < anotherVal ? -1 : (value == anotherVal ? 0 : 1);
}
/**
* Returns the String value of this mutable.
*
* @return the mutable value as a string
*/
public String toString() {
return String.valueOf(value);
}
}
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Provides mutable access to a value.
* <p>
* <code>Mutable</code> is used as a generic interface to the implementations in this package.
* <p>
* A typical use case would be to enable a primitive or string to be passed to a method and allow that method to
* effectively change the value of the primitive/string. Another use case is to store a frequently changing primitive in
* a collection (for example a total in a map) without needing to create new Integer/Long wrapper objects.
*
* @author Matthew Hawthorne
* @since 2.1
* @version $Id: Mutable.java 618693 2008-02-05 16:33:29Z sebb $
*/
interface Mutable {
/**
* Gets the value of this mutable.
*
* @return the stored value
*/
Object getValue();
/**
* Sets the value of this mutable.
*
* @param value
* the value to store
* @throws NullPointerException
* if the object is null and null is invalid
* @throws ClassCastException
* if the type is invalid
*/
void setValue(Object value);
}
Arithmetic Demo
/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
* Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistribution of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
public class ArithmeticDemo {
public static void main(String[] args) {
//a few numbers
int i = 37;
int j = 42;
double x = 27.475;
double y = 7.22;
System.out.println("Variable values...");
System.out.println(" i = " + i);
System.out.println(" j = " + j);
System.out.println(" x = " + x);
System.out.println(" y = " + y);
//adding numbers
System.out.println("Adding...");
System.out.println(" i + j = " + (i + j));
System.out.println(" x + y = " + (x + y));
//subtracting numbers
System.out.println("Subtracting...");
System.out.println(" i - j = " + (i - j));
System.out.println(" x - y = " + (x - y));
//multiplying numbers
System.out.println("Multiplying...");
System.out.println(" i * j = " + (i * j));
System.out.println(" x * y = " + (x * y));
//dividing numbers
System.out.println("Dividing...");
System.out.println(" i / j = " + (i / j));
System.out.println(" x / y = " + (x / y));
//computing the remainder resulting from dividing numbers
System.out.println("Computing the remainder...");
System.out.println(" i % j = " + (i % j));
System.out.println(" x % y = " + (x % y));
//mixing types
System.out.println("Mixing types...");
System.out.println(" j + y = " + (j + y));
System.out.println(" i * x = " + (i * x));
}
}
Built in types
/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS""
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
* pioneering role in inventing and promulgating (and standardizing) the Java
* language and environment is gratefully acknowledged.
*
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/
/**
* Built in types
*/
public class BuiltinTypes {
public static void main(String[] argv) {
// An integer can be entered in several ways:
int i = 123;
System.out.println("i = " + i);
i = 00123;
System.out.println("i = " + i);
i = 0x123;
System.out.println("i = " + i);
// A double can also be entered in several ways:
float f = 123f;
System.out.println("f = " + f);
f = 123.0f;
System.out.println("f = " + f);
f = (float)1.23e2; // 1.23 x (10 ^ 2)
System.out.println("f = " + f);
}
}
Convert Java Integer object to Numeric primitive types
public class Main {
public static void main(String[] args) {
Integer intObj = new Integer("10");
byte b = intObj.byteValue();
System.out.println(b);
short s = intObj.shortValue();
System.out.println(s);
int i = intObj.intValue();
System.out.println(i);
float f = intObj.floatValue();
System.out.println(f);
double d = intObj.doubleValue();
System.out.println(d);
}
}
Convert Java String to Integer object
public class Main {
public static void main(String[] args) {
Integer intObj1 = new Integer("100");
System.out.println(intObj1);
String str = "100";
Integer intObj2 = Integer.valueOf(str);
System.out.println(intObj2);
}
}
Convert primitive back and forth
public final class PrimitiveUtils {
public static Class getClass(String value) {
Class clz = null;
if ("int".equals(value)) {
clz = int.class;
}
if ("byte".equals(value)) {
clz = byte.class;
}
if ("short".equals(value)) {
clz = short.class;
}
if ("long".equals(value)) {
clz = long.class;
}
if ("float".equals(value)) {
clz = float.class;
}
if ("double".equals(value)) {
clz = double.class;
}
if ("boolean".equals(value)) {
clz = boolean.class;
}
if ("char".equals(value)) {
clz = char.class;
}
return clz;
}
public static Object read(String value, Class type) {
Object ret = value;
if (Integer.TYPE.equals(type)) {
ret = Integer.valueOf(value);
}
if (Byte.TYPE.equals(type)) {
ret = Byte.valueOf(value);
}
if (Short.TYPE.equals(type)) {
ret = Short.valueOf(value);
}
if (Long.TYPE.equals(type)) {
ret = Long.valueOf(value);
}
if (Float.TYPE.equals(type)) {
ret = Float.valueOf(value);
}
if (Double.TYPE.equals(type)) {
ret = Double.valueOf(value);
}
if (Boolean.TYPE.equals(type)) {
ret = Boolean.valueOf(value);
}
if (Character.TYPE.equals(type)) {
ret = value.charAt(0);
}
// TODO others.
return ret;
}
}
Convert the given array (which may be a primitive array) to an object array
import java.lang.reflect.Array;
import java.util.Arrays;
/*
* Copyright 2002-2007 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//Revised from springframework
/**
* Miscellaneous object utility methods. Mainly for internal use within the
* framework; consider Jakarta"s Commons Lang for a more comprehensive suite
* of object utilities.
*
* @author Juergen Hoeller
* @author Keith Donald
* @author Rod Johnson
* @author Rob Harrop
* @author Alex Ruiz
* @since 19.03.2004
* @see org.apache.rumons.lang.ObjectUtils
*/
abstract class ObjectUtils {
private static final int INITIAL_HASH = 7;
private static final int MULTIPLIER = 31;
private static final String EMPTY_STRING = "";
private static final String NULL_STRING = "null";
private static final String ARRAY_START = "{";
private static final String ARRAY_END = "}";
private static final String EMPTY_ARRAY = ARRAY_START + ARRAY_END;
private static final String ARRAY_ELEMENT_SEPARATOR = ", ";
/**
* Return whether the given array is empty: that is, <code>null</code>
* or of zero length.
* @param array the array to check
* @return whether the given array is empty
*/
public static boolean isEmpty(Object[] array) {
return (array == null || array.length == 0);
}
/**
* Append the given Object to the given array, returning a new array
* consisting of the input array contents plus the given Object.
* @param array the array to append to (can be <code>null</code>)
* @param obj the Object to append
* @return the new array (of the same component type; never <code>null</code>)
*/
public static Object[] addObjectToArray(Object[] array, Object obj) {
Class compType = Object.class;
if (array != null) {
compType = array.getClass().getComponentType();
}
else if (obj != null) {
compType = obj.getClass();
}
int newArrLength = (array != null ? array.length + 1 : 1);
Object[] newArr = (Object[]) Array.newInstance(compType, newArrLength);
if (array != null) {
System.arraycopy(array, 0, newArr, 0, array.length);
}
newArr[newArr.length - 1] = obj;
return newArr;
}
/**
* Convert the given array (which may be a primitive array) to an
* object array (if necessary of primitive wrapper objects).
* <p>A <code>null</code> source value will be converted to an
* empty Object array.
* @param source the (potentially primitive) array
* @return the corresponding object array (never <code>null</code>)
* @throws IllegalArgumentException if the parameter is not an array
*/
public static Object[] toObjectArray(Object source) {
if (source instanceof Object[]) {
return (Object[]) source;
}
if (source == null) {
return new Object[0];
}
if (!source.getClass().isArray()) {
throw new IllegalArgumentException("Source is not an array: " + source);
}
int length = Array.getLength(source);
if (length == 0) {
return new Object[0];
}
Class wrapperType = Array.get(source, 0).getClass();
Object[] newArray = (Object[]) Array.newInstance(wrapperType, length);
for (int i = 0; i < length; i++) {
newArray[i] = Array.get(source, i);
}
return newArray;
}
}
Create an Integer object
public class Main {
public static void main(String[] args) {
Integer intObj1 = new Integer(10);
Integer intObj2 = new Integer("10");
System.out.println(intObj1);
System.out.println(intObj2);
}
}
Data Type Print Test
/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
* Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistribution of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
public class DataTypePrintTest {
public static void main(String[] args) {
Thread objectData = new Thread();
String stringData = "Java Mania";
char[] charArrayData = { "a", "b", "c" };
int integerData = 4;
long longData = Long.MIN_VALUE;
float floatData = Float.MAX_VALUE;
double doubleData = Math.PI;
boolean booleanData = true;
System.out.println(objectData);
System.out.println(stringData);
System.out.println(charArrayData);
System.out.println(integerData);
System.out.println(longData);
System.out.println(floatData);
System.out.println(doubleData);
System.out.println(booleanData);
}
}
Demonstrates the ++ and -- operators
//: c03:AutoInc.java
// Demonstrates the ++ and -- operators.
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
public class AutoInc {
public static void main(String[] args) {
int i = 1;
System.out.println("i : " + i);
System.out.println("++i : " + ++i); // Pre-increment
System.out.println("i++ : " + i++); // Post-increment
System.out.println("i : " + i);
System.out.println("--i : " + --i); // Pre-decrement
System.out.println("i-- : " + i--); // Post-decrement
System.out.println("i : " + i);
}
} ///:~
Demonstrates the mathematical operators.
//: c03:MathOps.java
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
import java.util.*;
public class MathOps {
// Shorthand to print a string and an int:
static void printInt(String s, int i) {
System.out.println(s + " = " + i);
}
// Shorthand to print a string and a float:
static void printFloat(String s, float f) {
System.out.println(s + " = " + f);
}
public static void main(String[] args) {
// Create a random number generator,
// seeds with current time by default:
Random rand = new Random();
int i, j, k;
// Choose value from 1 to 100:
j = rand.nextInt(100) + 1;
k = rand.nextInt(100) + 1;
printInt("j", j); printInt("k", k);
i = j + k; printInt("j + k", i);
i = j - k; printInt("j - k", i);
i = k / j; printInt("k / j", i);
i = k * j; printInt("k * j", i);
i = k % j; printInt("k % j", i);
j %= k; printInt("j %= k", j);
// Floating-point number tests:
float u,v,w; // applies to doubles, too
v = rand.nextFloat();
w = rand.nextFloat();
printFloat("v", v); printFloat("w", w);
u = v + w; printFloat("v + w", u);
u = v - w; printFloat("v - w", u);
u = v * w; printFloat("v * w", u);
u = v / w; printFloat("v / w", u);
// the following also works for
// char, byte, short, int, long,
// and double:
u += v; printFloat("u += v", u);
u -= v; printFloat("u -= v", u);
u *= v; printFloat("u *= v", u);
u /= v; printFloat("u /= v", u);
}
} ///:~
Java lets you overflow
//: c03:Overflow.java
// Surprise! Java lets you overflow.
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
public class Overflow {
public static void main(String[] args) {
int big = 0x7fffffff; // max int value
System.out.println("big = " + big);
int bigger = big * 4;
System.out.println("bigger = " + bigger);
}
} ///:~
Java Type Helper
/*
* The contents of this file are subject to the terms
* of the Common Development and Distribution License
* (the "License"). You may not use this file except
* in compliance with the License.
*
* You can obtain a copy of the license at
* glassfish/bootstrap/legal/CDDLv1.0.txt or
* https://glassfish.dev.java.net/public/CDDLv1.0.html.
* See the License for the specific language governing
* permissions and limitations under the License.
*
* When distributing Covered Code, include this CDDL
* HEADER in each file and include the License file at
* glassfish/bootstrap/legal/CDDLv1.0.txt. If applicable,
* add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your
* own identifying information: Portions Copyright [yyyy]
* [name of copyright owner]
*/
/*
* JavaTypeHelper.java
*
* Created on January 22, 2002, 3:39 PM
*/
import java.util.HashMap;
import java.util.Map;
/**
* This is a helper class which provides some basic java type convenience
* methods: extraction of a package from a fully qualified class name,
* extraction of a short (non-qualified) name from a fully qualified class name,
* and various wrapper and primitive type methods.
* @author Rochelle Raccah
*/
public class JavaTypeHelper {
/**
* Map of primitive to wrapper classes
*/
private final static Map _primitiveToWrappers;
/**
* Map of primitive names to primitive classes
*/
private final static Map _primitiveNamesToPrimitives;
/**
* Map of primitive names to wrapper names
*/
private final static Map _primitiveNamesToWrapperNames;
/**
* Map of wrapper classes to primitive names
*/
private final static Map _wrapperToPrimitiveNames;
static {
_primitiveToWrappers = new HashMap(9);
_primitiveToWrappers.put(Boolean.TYPE, Boolean.class);
_primitiveToWrappers.put(Byte.TYPE, Byte.class);
_primitiveToWrappers.put(Character.TYPE, Character.class);
_primitiveToWrappers.put(Double.TYPE, Double.class);
_primitiveToWrappers.put(Float.TYPE, Float.class);
_primitiveToWrappers.put(Integer.TYPE, Integer.class);
_primitiveToWrappers.put(Long.TYPE, Long.class);
_primitiveToWrappers.put(Short.TYPE, Short.class);
_primitiveToWrappers.put(Void.TYPE, Void.class);
_primitiveNamesToPrimitives = new HashMap(9);
_primitiveNamesToPrimitives.put("boolean", Boolean.TYPE); // NOI18N
_primitiveNamesToPrimitives.put("byte", Byte.TYPE); // NOI18N
_primitiveNamesToPrimitives.put("char", Character.TYPE); // NOI18N
_primitiveNamesToPrimitives.put("double", Double.TYPE); // NOI18N
_primitiveNamesToPrimitives.put("float", Float.TYPE); // NOI18N
_primitiveNamesToPrimitives.put("int", Integer.TYPE); // NOI18N
_primitiveNamesToPrimitives.put("long", Long.TYPE); // NOI18N
_primitiveNamesToPrimitives.put("short", Short.TYPE); // NOI18N
_primitiveNamesToPrimitives.put("void", Void.TYPE); // NOI18N
_primitiveNamesToWrapperNames = new HashMap(9);
_primitiveNamesToWrapperNames.put("boolean", "Boolean"); // NOI18N
_primitiveNamesToWrapperNames.put("byte", "Byte"); // NOI18N
_primitiveNamesToWrapperNames.put("char", "Character"); // NOI18N
_primitiveNamesToWrapperNames.put("double", "Double"); // NOI18N
_primitiveNamesToWrapperNames.put("float", "Float"); // NOI18N
_primitiveNamesToWrapperNames.put("int", "Integer"); // NOI18N
_primitiveNamesToWrapperNames.put("long", "Long"); // NOI18N
_primitiveNamesToWrapperNames.put("short", "Short"); // NOI18N
_primitiveNamesToWrapperNames.put("void", "Void"); // NOI18N
_wrapperToPrimitiveNames = new HashMap(9);
_wrapperToPrimitiveNames.put(Boolean.class, "boolean"); // NOI18N
_wrapperToPrimitiveNames.put(Byte.class, "byte"); // NOI18N
_wrapperToPrimitiveNames.put(Character.class, "char"); // NOI18N
_wrapperToPrimitiveNames.put(Double.class, "double"); // NOI18N
_wrapperToPrimitiveNames.put(Float.class, "float"); // NOI18N
_wrapperToPrimitiveNames.put(Integer.class, "int"); // NOI18N
_wrapperToPrimitiveNames.put(Long.class, "long"); // NOI18N
_wrapperToPrimitiveNames.put(Short.class, "short"); // NOI18N
_wrapperToPrimitiveNames.put(Void.class, "void"); // NOI18N
}
/**
* Returns the package portion of the specified class
* @param className the name of the class from which to extract the package
* @return package portion of the specified class
*/
public static String getPackageName(final String className) {
if (className != null) {
final int index = className.lastIndexOf(".");
return ((index != -1) ? className.substring(0, index) : ""); // NOI18N
}
return null;
}
/**
* Returns the name of a class without the package name. For example: if
* input = "java.lang.Object" , then output = "Object".
* @param fully qualified classname
*/
public static String getShortClassName(final String className) {
if (className != null) {
final int index = className.lastIndexOf(".");
return className.substring(index + 1);
}
return null;
}
// primitive/wrapper class utilities
/**
* Returns the wrapper class associated with the supplied primitive class.
* @param primitive the primitive class to be used for lookup.
* @return the associated wrapper class.
*/
public static Class getWrapperClass(Class primitive) {
return (Class) _primitiveToWrappers.get(primitive);
}
/**
* Returns the primitive class associated with the supplied primitive type
* name.
* @param primitiveName the name of the primitive to be used for lookup.
* @return the associated primitive class.
*/
public static Class getPrimitiveClass(String primitiveName) {
return (Class) _primitiveNamesToPrimitives.get(primitiveName);
}
/**
* Returns the name of the wrapper class associated with the supplied
* primitive type name.
* @param primitiveName the name of the primitive to be used for lookup.
* @return the associated wrapper class name.
*/
public static String getWrapperName(String primitiveName) {
return (String) _primitiveNamesToWrapperNames.get(primitiveName);
}
/**
* Returns the name of the primitive type associated with the supplied
* wrapper class.
* @param wrapper the wrapper class to be used for lookup.
* @return the associated primitive type name.
*/
public static String getPrimitiveName(Class wrapper) {
return (String) _wrapperToPrimitiveNames.get(wrapper);
}
/**
* Returns the Boolean wrapper object for true or false corresponding to the
* supplied argument. This is to provide a convenience method for this
* conversion but to prevent calling the Boolean constructor which has been
* determined to be unnecessary and a performance problem. JDK 1.4 provides
* such a method, but some of our code still works with JDK 1.3.
* @param flag the primitive boolean object to be translated to a Boolean
* wrapper.
* @return the associated true/false shared wrapper object
*/
public static Boolean valueOf(boolean flag) {
return (flag ? Boolean.TRUE : Boolean.FALSE);
}
}
Literals
//: c03:Literals.java
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
public class Literals {
char c = 0xffff; // max char hex value
byte b = 0x7f; // max byte hex value
short s = 0x7fff; // max short hex value
int i1 = 0x2f; // Hexadecimal (lowercase)
int i2 = 0X2F; // Hexadecimal (uppercase)
int i3 = 0177; // Octal (leading zero)
// Hex and Oct also work with long.
long n1 = 200L; // long suffix
long n2 = 200l; // long suffix (but can be confusing)
long n3 = 200;
//! long l6(200); // not allowed
float f1 = 1;
float f2 = 1F; // float suffix
float f3 = 1f; // float suffix
float f4 = 1e-45f; // 10 to the power
float f5 = 1e+9f; // float suffix
double d1 = 1d; // double suffix
double d2 = 1D; // double suffix
double d3 = 47e47d; // 10 to the power
} ///:~
Max Variable Length Demo
/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
* Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistribution of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
public class MaxVariablesDemo {
public static void main(String args[]) {
// integers
byte largestByte = Byte.MAX_VALUE;
short largestShort = Short.MAX_VALUE;
int largestInteger = Integer.MAX_VALUE;
long largestLong = Long.MAX_VALUE;
/* real numbers*/
float largestFloat = Float.MAX_VALUE;
double largestDouble = Double.MAX_VALUE;
// other primitive types
char aChar = "S";
boolean aBoolean = true;
// display them all
System.out.println("The largest byte value is " + largestByte);
System.out.println("The largest short value is " + largestShort);
System.out.println("The largest integer value is " + largestInteger);
System.out.println("The largest long value is " + largestLong);
System.out.println("The largest float value is " + largestFloat);
System.out.println("The largest double value is " + largestDouble);
if (Character.isUpperCase(aChar)) {
System.out.println("The character " + aChar + " is upper case.");
} else {
System.out.println("The character " + aChar + " is lower case.");
}
System.out.println("The value of aBoolean is " + aBoolean);
}
}
Parse Number
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.NumberFormat;
import java.text.ParseException;
/**
* Miscellaneous utility methods for number conversion and parsing.
* Mainly for internal use within the framework; consider Jakarta"s
* Commons Lang for a more comprehensive suite of string utilities.
*
* @author Juergen Hoeller
* @author Rob Harrop
* @since 1.1.2
*/
public abstract class NumberUtils {
/**
* Convert the given number into an instance of the given target class.
*
* @param number the number to convert
* @param targetClass the target class to convert to
* @return the converted number
* @throws IllegalArgumentException if the target class is not supported
* (i.e. not a standard Number subclass as included in the JDK)
* @see java.lang.Byte
* @see java.lang.Short
* @see java.lang.Integer
* @see java.lang.Long
* @see java.math.BigInteger
* @see java.lang.Float
* @see java.lang.Double
* @see java.math.BigDecimal
*/
public static Number convertNumberToTargetClass(Number number, Class targetClass)
throws IllegalArgumentException {
if (targetClass.isInstance(number)) {
return number;
} else if (targetClass.equals(Byte.class)) {
long value = number.longValue();
if (value < Byte.MIN_VALUE || value > Byte.MAX_VALUE) {
raiseOverflowException(number, targetClass);
}
return number.byteValue();
} else if (targetClass.equals(Short.class)) {
long value = number.longValue();
if (value < Short.MIN_VALUE || value > Short.MAX_VALUE) {
raiseOverflowException(number, targetClass);
}
return number.shortValue();
} else if (targetClass.equals(Integer.class)) {
long value = number.longValue();
if (value < Integer.MIN_VALUE || value > Integer.MAX_VALUE) {
raiseOverflowException(number, targetClass);
}
return number.intValue();
} else if (targetClass.equals(Long.class)) {
return number.longValue();
} else if (targetClass.equals(Float.class)) {
return number.floatValue();
} else if (targetClass.equals(Double.class)) {
return number.doubleValue();
} else if (targetClass.equals(BigInteger.class)) {
return BigInteger.valueOf(number.longValue());
} else if (targetClass.equals(BigDecimal.class)) {
// using BigDecimal(String) here, to avoid unpredictability of BigDecimal(double)
// (see BigDecimal javadoc for details)
return new BigDecimal(number.toString());
} else {
throw new IllegalArgumentException("Could not convert number [" + number + "] of type [" +
number.getClass().getName() + "] to unknown target class [" + targetClass.getName() + "]");
}
}
/**
* Raise an overflow exception for the given number and target class.
*
* @param number the number we tried to convert
* @param targetClass the target class we tried to convert to
*/
private static void raiseOverflowException(Number number, Class targetClass) {
throw new IllegalArgumentException("Could not convert number [" + number + "] of type [" +
number.getClass().getName() + "] to target class [" + targetClass.getName() + "]: overflow");
}
/**
* Parse the given text into a number instance of the given target class,
* using the corresponding default <code>decode</code> methods. Trims the
* input <code>String</code> before attempting to parse the number. Supports
* numbers in hex format (with leading 0x) and in octal format (with leading 0).
*
* @param text the text to convert
* @param targetClass the target class to parse into
* @return the parsed number
* @throws IllegalArgumentException if the target class is not supported
* (i.e. not a standard Number subclass as included in the JDK)
* @see java.lang.Byte#decode
* @see java.lang.Short#decode
* @see java.lang.Integer#decode
* @see java.lang.Long#decode
* @see #decodeBigInteger(String)
* @see java.lang.Float#valueOf
* @see java.lang.Double#valueOf
* @see java.math.BigDecimal#BigDecimal(String)
*/
public static Number parseNumber(String text, Class targetClass) {
String trimmed = text.trim();
if (targetClass.equals(Byte.class)) {
return Byte.decode(trimmed);
} else if (targetClass.equals(Short.class)) {
return Short.decode(trimmed);
} else if (targetClass.equals(Integer.class)) {
return Integer.decode(trimmed);
} else if (targetClass.equals(Long.class)) {
return Long.decode(trimmed);
} else if (targetClass.equals(BigInteger.class)) {
return decodeBigInteger(trimmed);
} else if (targetClass.equals(Float.class)) {
return Float.valueOf(trimmed);
} else if (targetClass.equals(Double.class)) {
return Double.valueOf(trimmed);
} else if (targetClass.equals(BigDecimal.class) || targetClass.equals(Number.class)) {
return new BigDecimal(trimmed);
} else {
throw new IllegalArgumentException(
"Cannot convert String [" + text + "] to target class [" + targetClass.getName() + "]");
}
}
/**
* Parse the given text into a number instance of the given target class,
* using the given NumberFormat. Trims the input <code>String</code>
* before attempting to parse the number.
*
* @param text the text to convert
* @param targetClass the target class to parse into
* @param numberFormat the NumberFormat to use for parsing (if <code>null</code>,
* this method falls back to <code>parseNumber(String, Class)</code>)
* @return the parsed number
* @throws IllegalArgumentException if the target class is not supported
* (i.e. not a standard Number subclass as included in the JDK)
* @see java.text.NumberFormat#parse
* @see #convertNumberToTargetClass
* @see #parseNumber(String,Class)
*/
public static Number parseNumber(String text, Class targetClass, NumberFormat numberFormat) {
if (numberFormat != null) {
try {
Number number = numberFormat.parse(text.trim());
return convertNumberToTargetClass(number, targetClass);
}
catch (ParseException ex) {
throw new IllegalArgumentException(ex.getMessage());
}
} else {
return parseNumber(text, targetClass);
}
}
/**
* Decode a {@link java.math.BigInteger} from a {@link String} value.
* Supports decimal, hex and octal notation.
*
* @see BigInteger#BigInteger(String,int)
*/
private static BigInteger decodeBigInteger(String value) {
int radix = 10;
int index = 0;
boolean negative = false;
// Handle minus sign, if present.
if (value.startsWith("-")) {
negative = true;
index++;
}
// Handle radix specifier, if present.
if (value.startsWith("0x", index) || value.startsWith("0X", index)) {
index += 2;
radix = 16;
} else if (value.startsWith("#", index)) {
index++;
radix = 16;
} else if (value.startsWith("0", index) && value.length() > 1 + index) {
index++;
radix = 8;
}
BigInteger result = new BigInteger(value.substring(index), radix);
return (negative ? result.negate() : result);
}
}
Primitive utilities
/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
/**
* Primitive utilities.
*
* @version <tt>$Revision: 1958 $</tt>
* @author
*/
public final class Primitives {
/**
* Get a Boolean from a boolean, equivalent to the java 1.4 method
* Boolean.valueOf(boolean)
*
* @param value
* the boolean
* @return the Boolean equivalent
*/
public static Boolean valueOf(boolean value) {
if (value)
return Boolean.TRUE;
else
return Boolean.FALSE;
}
/**
* Test the equality of two doubles by converting their values into IEEE 754
* floating-point "double format" long values.
*
* @param a
* Double to check equality with.
* @param b
* Double to check equality with.
* @return True if a equals b.
*/
public static boolean equals(final double a, final double b) {
return Double.doubleToLongBits(a) == Double.doubleToLongBits(b);
}
/**
* Test the equality of two doubles by converting their values into IEEE 754
* floating-point "single precision" bit layouts.
*
* @param a
* Float to check equality with.
* @param b
* Float to check equality with.
* @return True if a equals b.
*/
public static boolean equals(final float a, final float b) {
return Float.floatToIntBits(a) == Float.floatToIntBits(b);
}
/**
* Test the equality of a given sub-section of two byte arrays.
*
* @param a
* The first byte array.
* @param abegin
* The begining index of the first byte array.
* @param b
* The second byte array.
* @param bbegin
* The begining index of the second byte array.
* @param length
* The length of the sub-section.
* @return True if sub-sections are equal.
*/
public static boolean equals(final byte a[], final int abegin, final byte b[], final int bbegin,
final int length) {
try {
int i = length;
while (--i >= 0) {
if (a[abegin + i] != b[bbegin + i]) {
return false;
}
}
} catch (ArrayIndexOutOfBoundsException e) {
return false;
}
return true;
}
/**
* Test the equality of two byte arrays.
*
* @param a
* The first byte array.
* @param b
* The second byte array.
* @return True if the byte arrays are equal.
*/
public static boolean equals(final byte a[], final byte b[]) {
if (a == b)
return true;
if (a == null || b == null)
return false;
if (a.length != b.length)
return false;
try {
for (int i = 0; i < a.length; i++) {
if (a[i] != b[i]) {
return false;
}
}
} catch (ArrayIndexOutOfBoundsException e) {
return false;
}
return true;
}
}
Relational Demo
/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
* Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistribution of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
public class RelationalDemo {
public static void main(String[] args) {
//a few numbers
int i = 37;
int j = 42;
int k = 42;
System.out.println("Variable values...");
System.out.println(" i = " + i);
System.out.println(" j = " + j);
System.out.println(" k = " + k);
//greater than
System.out.println("Greater than...");
System.out.println(" i > j is " + (i > j)); //false
System.out.println(" j > i is " + (j > i)); //true
System.out.println(" k > j is " + (k > j)); //false, they are equal
//greater than or equal to
System.out.println("Greater than or equal to...");
System.out.println(" i >= j is " + (i >= j)); //false
System.out.println(" j >= i is " + (j >= i)); //true
System.out.println(" k >= j is " + (k >= j)); //true
//less than
System.out.println("Less than...");
System.out.println(" i < j is " + (i < j)); //true
System.out.println(" j < i is " + (j < i)); //false
System.out.println(" k < j is " + (k < j)); //false
//less than or equal to
System.out.println("Less than or equal to...");
System.out.println(" i <= j is " + (i <= j)); //true
System.out.println(" j <= i is " + (j <= i)); //false
System.out.println(" k <= j is " + (k <= j)); //true
//equal to
System.out.println("Equal to...");
System.out.println(" i == j is " + (i == j)); //false
System.out.println(" k == j is " + (k == j)); //true
//not equal to
System.out.println("Not equal to...");
System.out.println(" i != j is " + (i != j)); //true
System.out.println(" k != j is " + (k != j)); //false
}
}
Returns a default value if the object passed is null
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.Serializable;
/**
* <p>Operations on <code>Object</code>.</p>
*
* <p>This class tries to handle <code>null</code> input gracefully.
* An exception will generally not be thrown for a <code>null</code> input.
* Each method documents its behaviour in more detail.</p>
*
* @author
* @since 1.0
* @version $Id: ObjectUtils.java 594336 2007-11-12 22:54:02Z bayard $
*/
public class ObjectUtils {
/**
* <p>Singleton used as a <code>null</code> placeholder where
* <code>null</code> has another meaning.</p>
*
* <p>For example, in a <code>HashMap</code> the
* {@link java.util.HashMap#get(java.lang.Object)} method returns
* <code>null</code> if the <code>Map</code> contains
* <code>null</code> or if there is no matching key. The
* <code>Null</code> placeholder can be used to distinguish between
* these two cases.</p>
*
* <p>Another example is <code>Hashtable</code>, where <code>null</code>
* cannot be stored.</p>
*
* <p>This instance is Serializable.</p>
*/
public static final Null NULL = new Null();
/**
* <p><code>ObjectUtils</code> instances should NOT be constructed in
* standard programming. Instead, the class should be used as
* <code>ObjectUtils.defaultIfNull("a","b");</code>.</p>
*
* <p>This constructor is public to permit tools that require a JavaBean instance
* to operate.</p>
*/
public ObjectUtils() {
super();
}
// Defaulting
//-----------------------------------------------------------------------
/**
* <p>Returns a default value if the object passed is
* <code>null</code>.</p>
*
* <pre>
* ObjectUtils.defaultIfNull(null, null) = null
* ObjectUtils.defaultIfNull(null, "") = ""
* ObjectUtils.defaultIfNull(null, "zz") = "zz"
* ObjectUtils.defaultIfNull("abc", *) = "abc"
* ObjectUtils.defaultIfNull(Boolean.TRUE, *) = Boolean.TRUE
* </pre>
*
* @param object the <code>Object</code> to test, may be <code>null</code>
* @param defaultValue the default value to return, may be <code>null</code>
* @return <code>object</code> if it is not <code>null</code>, defaultValue otherwise
*/
public static Object defaultIfNull(Object object, Object defaultValue) {
return object != null ? object : defaultValue;
}
/**
* <p>Compares two objects for equality, where either one or both
* objects may be <code>null</code>.</p>
*
* <pre>
* ObjectUtils.equals(null, null) = true
* ObjectUtils.equals(null, "") = false
* ObjectUtils.equals("", null) = false
* ObjectUtils.equals("", "") = true
* ObjectUtils.equals(Boolean.TRUE, null) = false
* ObjectUtils.equals(Boolean.TRUE, "true") = false
* ObjectUtils.equals(Boolean.TRUE, Boolean.TRUE) = true
* ObjectUtils.equals(Boolean.TRUE, Boolean.FALSE) = false
* </pre>
*
* @param object1 the first object, may be <code>null</code>
* @param object2 the second object, may be <code>null</code>
* @return <code>true</code> if the values of both objects are the same
*/
public static boolean equals(Object object1, Object object2) {
if (object1 == object2) {
return true;
}
if ((object1 == null) || (object2 == null)) {
return false;
}
return object1.equals(object2);
}
/**
* <p>Gets the hash code of an object returning zero when the
* object is <code>null</code>.</p>
*
* <pre>
* ObjectUtils.hashCode(null) = 0
* ObjectUtils.hashCode(obj) = obj.hashCode()
* </pre>
*
* @param obj the object to obtain the hash code of, may be <code>null</code>
* @return the hash code of the object, or zero if null
* @since 2.1
*/
public static int hashCode(Object obj) {
return (obj == null) ? 0 : obj.hashCode();
}
// Identity ToString
//-----------------------------------------------------------------------
/**
* <p>Gets the toString that would be produced by <code>Object</code>
* if a class did not override toString itself. <code>null</code>
* will return <code>null</code>.</p>
*
* <pre>
* ObjectUtils.identityToString(null) = null
* ObjectUtils.identityToString("") = "java.lang.String@1e23"
* ObjectUtils.identityToString(Boolean.TRUE) = "java.lang.Boolean@7fa"
* </pre>
*
* @param object the object to create a toString for, may be
* <code>null</code>
* @return the default toString text, or <code>null</code> if
* <code>null</code> passed in
*/
public static String identityToString(Object object) {
if (object == null) {
return null;
}
StringBuffer buffer = new StringBuffer();
identityToString(buffer, object);
return buffer.toString();
}
/**
* <p>Appends the toString that would be produced by <code>Object</code>
* if a class did not override toString itself. <code>null</code>
* will throw a NullPointerException for either of the two parameters. </p>
*
* <pre>
* ObjectUtils.identityToString(buf, "") = buf.append("java.lang.String@1e23"
* ObjectUtils.identityToString(buf, Boolean.TRUE) = buf.append("java.lang.Boolean@7fa"
* ObjectUtils.identityToString(buf, Boolean.TRUE) = buf.append("java.lang.Boolean@7fa")
* </pre>
*
* @param buffer the buffer to append to
* @param object the object to create a toString for
* @since 2.4
*/
public static void identityToString(StringBuffer buffer, Object object) {
if (object == null) {
throw new NullPointerException("Cannot get the toString of a null identity");
}
buffer.append(object.getClass().getName())
.append("@")
.append(Integer.toHexString(System.identityHashCode(object)));
}
// ToString
//-----------------------------------------------------------------------
/**
* <p>Gets the <code>toString</code> of an <code>Object</code> returning
* an empty string ("") if <code>null</code> input.</p>
*
* <pre>
* ObjectUtils.toString(null) = ""
* ObjectUtils.toString("") = ""
* ObjectUtils.toString("bat") = "bat"
* ObjectUtils.toString(Boolean.TRUE) = "true"
* </pre>
*
* @see StringUtils#defaultString(String)
* @see String#valueOf(Object)
* @param obj the Object to <code>toString</code>, may be null
* @return the passed in Object"s toString, or nullStr if <code>null</code> input
* @since 2.0
*/
public static String toString(Object obj) {
return obj == null ? "" : obj.toString();
}
/**
* <p>Gets the <code>toString</code> of an <code>Object</code> returning
* a specified text if <code>null</code> input.</p>
*
* <pre>
* ObjectUtils.toString(null, null) = null
* ObjectUtils.toString(null, "null") = "null"
* ObjectUtils.toString("", "null") = ""
* ObjectUtils.toString("bat", "null") = "bat"
* ObjectUtils.toString(Boolean.TRUE, "null") = "true"
* </pre>
*
* @see StringUtils#defaultString(String,String)
* @see String#valueOf(Object)
* @param obj the Object to <code>toString</code>, may be null
* @param nullStr the String to return if <code>null</code> input, may be null
* @return the passed in Object"s toString, or nullStr if <code>null</code> input
* @since 2.0
*/
public static String toString(Object obj, String nullStr) {
return obj == null ? nullStr : obj.toString();
}
// Null
//-----------------------------------------------------------------------
/**
* <p>Class used as a null placeholder where <code>null</code>
* has another meaning.</p>
*
* <p>For example, in a <code>HashMap</code> the
* {@link java.util.HashMap#get(java.lang.Object)} method returns
* <code>null</code> if the <code>Map</code> contains
* <code>null</code> or if there is no matching key. The
* <code>Null</code> placeholder can be used to distinguish between
* these two cases.</p>
*
* <p>Another example is <code>Hashtable</code>, where <code>null</code>
* cannot be stored.</p>
*/
public static class Null implements Serializable {
/**
* Required for serialization support. Declare serialization compatibility with Commons Lang 1.0
*
* @see java.io.Serializable
*/
private static final long serialVersionUID = 7092611880189329093L;
/**
* Restricted constructor - singleton.
*/
Null() {
super();
}
/**
* <p>Ensure singleton.</p>
*
* @return the singleton value
*/
private Object readResolve() {
return ObjectUtils.NULL;
}
}
}
Shows default initial values
// : c04:InitialValues.java
// Shows default initial values.
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
public class InitialValues {
boolean t;
char c;
byte b;
short s;
int i;
long l;
float f;
double d;
void print(String s) {
System.out.println(s);
}
void printInitialValues() {
print("Data type Initial value");
print("boolean " + t);
print("char [" + c + "]");
print("byte " + b);
print("short " + s);
print("int " + i);
print("long " + l);
print("float " + f);
print("double " + d);
}
public static void main(String[] args) {
InitialValues iv = new InitialValues();
iv.printInitialValues();
/*
* You could also say: new InitialValues().printInitialValues();
*/
}
} ///:~
Tests all the operators on all the primitive data types
//: c03:AllOps.java
// Tests all the operators on all the primitive data types
// to show which ones are accepted by the Java compiler.
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
public class AllOps {
// To accept the results of a boolean test:
void f(boolean b) {}
void boolTest(boolean x, boolean y) {
// Arithmetic operators:
//! x = x * y;
//! x = x / y;
//! x = x % y;
//! x = x + y;
//! x = x - y;
//! x++;
//! x--;
//! x = +y;
//! x = -y;
// Relational and logical:
//! f(x > y);
//! f(x >= y);
//! f(x < y);
//! f(x <= y);
f(x == y);
f(x != y);
f(!y);
x = x && y;
x = x || y;
// Bitwise operators:
//! x = ~y;
x = x & y;
x = x | y;
x = x ^ y;
//! x = x << 1;
//! x = x >> 1;
//! x = x >>> 1;
// Compound assignment:
//! x += y;
//! x -= y;
//! x *= y;
//! x /= y;
//! x %= y;
//! x <<= 1;
//! x >>= 1;
//! x >>>= 1;
x &= y;
x ^= y;
x |= y;
// Casting:
//! char c = (char)x;
//! byte B = (byte)x;
//! short s = (short)x;
//! int i = (int)x;
//! long l = (long)x;
//! float f = (float)x;
//! double d = (double)x;
}
void charTest(char x, char y) {
// Arithmetic operators:
x = (char)(x * y);
x = (char)(x / y);
x = (char)(x % y);
x = (char)(x + y);
x = (char)(x - y);
x++;
x--;
x = (char)+y;
x = (char)-y;
// Relational and logical:
f(x > y);
f(x >= y);
f(x < y);
f(x <= y);
f(x == y);
f(x != y);
//! f(!x);
//! f(x && y);
//! f(x || y);
// Bitwise operators:
x= (char)~y;
x = (char)(x & y);
x = (char)(x | y);
x = (char)(x ^ y);
x = (char)(x << 1);
x = (char)(x >> 1);
x = (char)(x >>> 1);
// Compound assignment:
x += y;
x -= y;
x *= y;
x /= y;
x %= y;
x <<= 1;
x >>= 1;
x >>>= 1;
x &= y;
x ^= y;
x |= y;
// Casting:
//! boolean b = (boolean)x;
byte B = (byte)x;
short s = (short)x;
int i = (int)x;
long l = (long)x;
float f = (float)x;
double d = (double)x;
}
void byteTest(byte x, byte y) {
// Arithmetic operators:
x = (byte)(x* y);
x = (byte)(x / y);
x = (byte)(x % y);
x = (byte)(x + y);
x = (byte)(x - y);
x++;
x--;
x = (byte)+ y;
x = (byte)- y;
// Relational and logical:
f(x > y);
f(x >= y);
f(x < y);
f(x <= y);
f(x == y);
f(x != y);
//! f(!x);
//! f(x && y);
//! f(x || y);
// Bitwise operators:
x = (byte)~y;
x = (byte)(x & y);
x = (byte)(x | y);
x = (byte)(x ^ y);
x = (byte)(x << 1);
x = (byte)(x >> 1);
x = (byte)(x >>> 1);
// Compound assignment:
x += y;
x -= y;
x *= y;
x /= y;
x %= y;
x <<= 1;
x >>= 1;
x >>>= 1;
x &= y;
x ^= y;
x |= y;
// Casting:
//! boolean b = (boolean)x;
char c = (char)x;
short s = (short)x;
int i = (int)x;
long l = (long)x;
float f = (float)x;
double d = (double)x;
}
void shortTest(short x, short y) {
// Arithmetic operators:
x = (short)(x * y);
x = (short)(x / y);
x = (short)(x % y);
x = (short)(x + y);
x = (short)(x - y);
x++;
x--;
x = (short)+y;
x = (short)-y;
// Relational and logical:
f(x > y);
f(x >= y);
f(x < y);
f(x <= y);
f(x == y);
f(x != y);
//! f(!x);
//! f(x && y);
//! f(x || y);
// Bitwise operators:
x = (short)~y;
x = (short)(x & y);
x = (short)(x | y);
x = (short)(x ^ y);
x = (short)(x << 1);
x = (short)(x >> 1);
x = (short)(x >>> 1);
// Compound assignment:
x += y;
x -= y;
x *= y;
x /= y;
x %= y;
x <<= 1;
x >>= 1;
x >>>= 1;
x &= y;
x ^= y;
x |= y;
// Casting:
//! boolean b = (boolean)x;
char c = (char)x;
byte B = (byte)x;
int i = (int)x;
long l = (long)x;
float f = (float)x;
double d = (double)x;
}
void intTest(int x, int y) {
// Arithmetic operators:
x = x * y;
x = x / y;
x = x % y;
x = x + y;
x = x - y;
x++;
x--;
x = +y;
x = -y;
// Relational and logical:
f(x > y);
f(x >= y);
f(x < y);
f(x <= y);
f(x == y);
f(x != y);
//! f(!x);
//! f(x && y);
//! f(x || y);
// Bitwise operators:
x = ~y;
x = x & y;
x = x | y;
x = x ^ y;
x = x << 1;
x = x >> 1;
x = x >>> 1;
// Compound assignment:
x += y;
x -= y;
x *= y;
x /= y;
x %= y;
x <<= 1;
x >>= 1;
x >>>= 1;
x &= y;
x ^= y;
x |= y;
// Casting:
//! boolean b = (boolean)x;
char c = (char)x;
byte B = (byte)x;
short s = (short)x;
long l = (long)x;
float f = (float)x;
double d = (double)x;
}
void longTest(long x, long y) {
// Arithmetic operators:
x = x * y;
x = x / y;
x = x % y;
x = x + y;
x = x - y;
x++;
x--;
x = +y;
x = -y;
// Relational and logical:
f(x > y);
f(x >= y);
f(x < y);
f(x <= y);
f(x == y);
f(x != y);
//! f(!x);
//! f(x && y);
//! f(x || y);
// Bitwise operators:
x = ~y;
x = x & y;
x = x | y;
x = x ^ y;
x = x << 1;
x = x >> 1;
x = x >>> 1;
// Compound assignment:
x += y;
x -= y;
x *= y;
x /= y;
x %= y;
x <<= 1;
x >>= 1;
x >>>= 1;
x &= y;
x ^= y;
x |= y;
// Casting:
//! boolean b = (boolean)x;
char c = (char)x;
byte B = (byte)x;
short s = (short)x;
int i = (int)x;
float f = (float)x;
double d = (double)x;
}
void floatTest(float x, float y) {
// Arithmetic operators:
x = x * y;
x = x / y;
x = x % y;
x = x + y;
x = x - y;
x++;
x--;
x = +y;
x = -y;
// Relational and logical:
f(x > y);
f(x >= y);
f(x < y);
f(x <= y);
f(x == y);
f(x != y);
//! f(!x);
//! f(x && y);
//! f(x || y);
// Bitwise operators:
//! x = ~y;
//! x = x & y;
//! x = x | y;
//! x = x ^ y;
//! x = x << 1;
//! x = x >> 1;
//! x = x >>> 1;
// Compound assignment:
x += y;
x -= y;
x *= y;
x /= y;
x %= y;
//! x <<= 1;
//! x >>= 1;
//! x >>>= 1;
//! x &= y;
//! x ^= y;
//! x |= y;
// Casting:
//! boolean b = (boolean)x;
char c = (char)x;
byte B = (byte)x;
short s = (short)x;
int i = (int)x;
long l = (long)x;
double d = (double)x;
}
void doubleTest(double x, double y) {
// Arithmetic operators:
x = x * y;
x = x / y;
x = x % y;
x = x + y;
x = x - y;
x++;
x--;
x = +y;
x = -y;
// Relational and logical:
f(x > y);
f(x >= y);
f(x < y);
f(x <= y);
f(x == y);
f(x != y);
//! f(!x);
//! f(x && y);
//! f(x || y);
// Bitwise operators:
//! x = ~y;
//! x = x & y;
//! x = x | y;
//! x = x ^ y;
//! x = x << 1;
//! x = x >> 1;
//! x = x >>> 1;
// Compound assignment:
x += y;
x -= y;
x *= y;
x /= y;
x %= y;
//! x <<= 1;
//! x >>= 1;
//! x >>>= 1;
//! x &= y;
//! x ^= y;
//! x |= y;
// Casting:
//! boolean b = (boolean)x;
char c = (char)x;
byte B = (byte)x;
short s = (short)x;
int i = (int)x;
long l = (long)x;
float f = (float)x;
}
} ///:~
Use Integer constructor to convert int primitive type to Integer object.
public class Main {
public static void main(String[] args) {
int i = 10;
Integer intObj = new Integer(i);
System.out.println(intObj);
}
}
