Java Tutorial/Data Type/Number
Версия от 17:44, 31 мая 2010; (обсуждение)
Содержание
An integer synchronized counter class.
/*
* 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.
*/
package org.jboss.util;
import java.io.Serializable;
/**
* An integer counter class.
*
* @version <tt>$Revision: 2800 $</tt>
* @author
*/
public class Counter
implements Serializable, Cloneable
{
/** The serialVersionUID */
private static final long serialVersionUID = 7736259185393081556L;
/** The current count */
private int count;
/**
* Construct a Counter with a starting value.
*
* @param count Starting value for counter.
*/
public Counter(final int count) {
this.count = count;
}
/**
* Construct a Counter.
*/
public Counter() {}
/**
* Increment the counter. (Optional operation)
*
* @return The incremented value of the counter.
*/
public int increment() {
return ++count;
}
/**
* Decrement the counter. (Optional operation)
*
* @return The decremented value of the counter.
*/
public int decrement() {
return --count;
}
/**
* Return the current value of the counter.
*
* @return The current value of the counter.
*/
public int getCount() {
return count;
}
/**
* Reset the counter to zero. (Optional operation)
*/
public void reset() {
this.count = 0;
}
/**
* Check if the given object is equal to this.
*
* @param obj Object to test equality with.
* @return True if object is equal to this.
*/
public boolean equals(final Object obj) {
if (obj == this) return true;
if (obj != null && obj.getClass() == getClass()) {
return ((Counter)obj).count == count;
}
return false;
}
/**
* Return a string representation of this.
*
* @return A string representation of this.
*/
public String toString() {
return String.valueOf(count);
}
/**
* Return a cloned copy of this object.
*
* @return A cloned copy of this object.
*/
public Object clone() {
try {
return super.clone();
}
catch (CloneNotSupportedException e) {
throw new InternalError();
}
}
/////////////////////////////////////////////////////////////////////////
// Wrappers //
/////////////////////////////////////////////////////////////////////////
/**
* Base wrapper class for other wrappers.
*/
private static class Wrapper
extends Counter
{
/** The serialVersionUID */
private static final long serialVersionUID = -1803971437884946242L;
/** The wrapped counter */
protected final Counter counter;
public Wrapper(final Counter counter) {
this.counter = counter;
}
public int increment() {
return counter.increment();
}
public int decrement() {
return counter.decrement();
}
public int getCount() {
return counter.getCount();
}
public void reset() {
counter.reset();
}
public boolean equals(final Object obj) {
return counter.equals(obj);
}
public String toString() {
return counter.toString();
}
public Object clone() {
return counter.clone();
}
}
/**
* Return a synchronized counter.
*
* @param counter Counter to synchronize.
* @return Synchronized counter.
*/
public static Counter makeSynchronized(final Counter counter) {
return new Wrapper(counter) {
/** The serialVersionUID */
private static final long serialVersionUID = -6024309396861726945L;
public synchronized int increment() {
return this.counter.increment();
}
public synchronized int decrement() {
return this.counter.decrement();
}
public synchronized int getCount() {
return this.counter.getCount();
}
public synchronized void reset() {
this.counter.reset();
}
public synchronized int hashCode() {
return this.counter.hashCode();
}
public synchronized boolean equals(final Object obj) {
return this.counter.equals(obj);
}
public synchronized String toString() {
return this.counter.toString();
}
public synchronized Object clone() {
return this.counter.clone();
}
};
}
/**
* Returns a directional counter.
*
* @param counter Counter to make directional.
* @param increasing True to create an increasing only
* or false to create a decreasing only.
* @return A directional counter.
*/
public static Counter makeDirectional(final Counter counter,
final boolean increasing)
{
Counter temp;
if (increasing) {
temp = new Wrapper(counter) {
/** The serialVersionUID */
private static final long serialVersionUID = 2161377898611431781L;
public int decrement() {
throw new UnsupportedOperationException();
}
public void reset() {
throw new UnsupportedOperationException();
}
};
}
else {
temp = new Wrapper(counter) {
/** The serialVersionUID */
private static final long serialVersionUID = -4683457706354663230L;
public int increment() {
throw new UnsupportedOperationException();
}
};
}
return temp;
}
}
Check Number properties and convert from Number
/**
* Copyright 2004, 2005, 2006 Odysseus Software GmbH
*
* 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.
*/
import java.math.BigDecimal;
import java.math.BigInteger;
/**
* Number utilities.
*
* Allows to convert between different <code>java.lang.Number</code>
* implementations with a minimum of lost information regarding the
* value of the represented number. Additionally, a few number tests
* are implemented and exact comparisons of arbitrary numbers may be
* performed.
*
* NOTE: Though some of the methods may give more or less useful results
* for custom number implementations, they are intended to work only
* with the predefined types (i.e., <code>Byte, Short, Integer, Long,
* Float, Double, BigInteger, BigDecimal</code>).
*
* @author Oliver Stuhr
*/
public class NumberUtils {
/**
* Answers <code>true</code> iff the given number is an instance of
* <code>java.math.BigDecimal</code> or <code>java.math.BigInteger</code>.
*
* @param number
* @return boolean
*/
public static boolean isBig(Number number) {
return number instanceof BigDecimal || number instanceof BigInteger;
}
/**
* Answers <code>true</code> iff the given number is an instance of
* <code>Byte</code>, <code>Short</code>, <code>Integer</code> or <code>Long</code>.
*
* @param number
* @return boolean
*/
public static boolean isLongCompatible(Number number) {
return number instanceof Byte || number instanceof Short || number instanceof Integer || number instanceof Long;
}
/**
* Answers <code>true</code> iff the given number is an instance of
* <code>Float</code> or <code>Double</code>.
*
* @param number
* @return boolean
*/
public static boolean isDoubleCompatible(Number number) {
return number instanceof Float || number instanceof Double;
}
/**
* Answers <code>true</code> iff the given number is infinite (i.e., is
* a <code>Float</code> or <code>Double</code> containing one of the
* predefined constant values representing positive or negative infinity).
*
* @param number
* @return boolean
*/
public static boolean isInfinite(Number number) {
if (number instanceof Double && ((Double)number).isInfinite())
return true;
if (number instanceof Float && ((Float)number).isInfinite())
return true;
return false;
}
/**
* Answers <code>true</code> iff the given number is "not a number"
* (i.e., is a <code>Float</code> or <code>Double</code> containing
* one of the predefined constant values representing <code>NaN</code>).
*
* @param number
* @return boolean
*/
public static boolean isNaN(Number number) {
if (number instanceof Double && ((Double)number).isNaN())
return true;
if (number instanceof Float && ((Float)number).isNaN())
return true;
return false;
}
/**
* Answers the signum function of the given number
* (i.e., <code>-1</code> if it is negative, <code>0</code>
* if it is zero and <code>1</code> if it is positive).
*
* @param number
* @return int
* @throws ArithmeticException The given number is <code>null</code> or "not a number".
*/
public static int signum(Number number) throws ArithmeticException {
if (number == null || isNaN(number))
throw new ArithmeticException("Argument must not be null or NaN.");
if (isLongCompatible(number)) {
long value = number.longValue();
return value < 0 ? -1 : value == 0 ? 0 : 1;
} else if (number instanceof BigInteger)
return ((BigInteger)number).signum();
else if (number instanceof BigDecimal)
return ((BigDecimal)number).signum();
else { // => isDoubleCompatible(number) or unknown Number type
double value = number.doubleValue();
return value < 0 ? -1 : value == 0 ? 0 : 1;
}
}
/**
* Converts the given number to a <code>Byte</code> (by using <code>byteValue()</code>).
*
* @param number
* @return java.lang.Byte
* @throws IllegalArgumentException The given number is "not a number" or infinite.
*/
public static Byte toByte(Number number) throws IllegalArgumentException {
if (number == null || number instanceof Byte)
return (Byte)number;
if (isNaN(number) || isInfinite(number))
throw new IllegalArgumentException("Argument must not be NaN or infinite.");
return new Byte(number.byteValue());
}
/**
* Converts the given number to a <code>Short</code> (by using <code>shortValue()</code>).
*
* @param number
* @return java.lang.Short
* @throws IllegalArgumentException The given number is "not a number" or infinite.
*/
public static Short toShort(Number number) throws IllegalArgumentException {
if (number == null || number instanceof Short)
return (Short)number;
if (isNaN(number) || isInfinite(number))
throw new IllegalArgumentException("Argument must not be NaN or infinite.");
return new Short(number.shortValue());
}
/**
* Converts the given number to a <code>Integer</code> (by using <code>intValue()</code>).
*
* @param number
* @return java.lang.Integer
* @throws IllegalArgumentException The given number is "not a number" or infinite.
*/
public static Integer toInteger(Number number) throws IllegalArgumentException {
if (number == null || number instanceof Integer)
return (Integer)number;
if (isNaN(number) || isInfinite(number))
throw new IllegalArgumentException("Argument must not be NaN or infinite.");
return new Integer(number.intValue());
}
/**
* Converts the given number to a <code>Long</code> (by using <code>longValue()</code>).
*
* @param number
* @return java.lang.Long
* @throws IllegalArgumentException The given number is "not a number" or infinite.
*/
public static Long toLong(Number number) throws IllegalArgumentException {
if (number == null || number instanceof Long)
return (Long)number;
if (isNaN(number) || isInfinite(number))
throw new IllegalArgumentException("Argument must not be NaN or infinite.");
return new Long(number.longValue());
}
/**
* Converts the given number to a <code>Float</code> (by using <code>floatValue()</code>).
*
* @param number
* @return java.lang.Float
*/
public static Float toFloat(Number number) {
return number == null || number instanceof Float ? (Float)number : new Float(number.floatValue());
}
/**
* Converts the given number to a <code>Double</code> (by using <code>doubleValue()</code>).
*
* @param number
* @return java.lang.Double
*/
public static Double toDouble(Number number) {
return number == null || number instanceof Double ? (Double)number : new Double(number.doubleValue());
}
/**
* Converts the given number to a <code>java.math.BigInteger</code>.
*
* @param number
* @return java.math.BigInteger
* @throws IllegalArgumentException The given number is "not a number" or infinite.
*/
public static BigInteger toBigInteger(Number number) throws IllegalArgumentException {
if (number == null || number instanceof BigInteger)
return (BigInteger)number;
if (number instanceof BigDecimal)
return ((BigDecimal)number).toBigInteger();
if (isDoubleCompatible(number)) {
if (isNaN(number) || isInfinite(number))
throw new IllegalArgumentException("Argument must not be NaN or infinite.");
return new BigDecimal(number.toString()).toBigInteger();
} // => isLongCompatible(number) or unknown Number type
return BigInteger.valueOf(number.longValue());
}
/**
* Converts the given number to a <code>java.math.BigDecimal</code>.
*
* @param number
* @return java.math.BigDecimal
* @throws IllegalArgumentException The given number is "not a number" or infinite.
*/
public static BigDecimal toBigDecimal(Number number) throws IllegalArgumentException {
if (number == null || number instanceof BigDecimal)
return (BigDecimal)number;
if (number instanceof BigInteger)
return new BigDecimal((BigInteger)number);
if (isDoubleCompatible(number)) {
if (isNaN(number) || isInfinite(number))
throw new IllegalArgumentException("Argument must not be NaN or infinite.");
return new BigDecimal(number.toString());
}
if (isLongCompatible(number))
return BigDecimal.valueOf(number.longValue());
// => unknown Number type
return new BigDecimal(String.valueOf(number.doubleValue()));
}
/**
* Compares the first number to the second one numerically and
* returns an integer depending on the comparison result:
* a negative value if the first number is the smaller one,
* a zero value if they are equal, and
* a positive value if the first number is the larger one.
*
* The main strategy goes like follows:
* 1. If one of the arguments is <code>null</code> or "not a number",
* throw an exception.
* 2. If both values are "long compatible", compare their <code>longValue()</code>
* using the usual comparison operators for primitive types (<, ==, >).
* 3. If both values are "double compatible", compare their <code>doubleValue()</code>
* using the usual comparison operators for primitive types (<, ==, >).
* 4. If one of the values is infinite (and the other is finite),
* determine the result depending on the sign of the infinite value.
* 5. Otherwise convert both values to <code>java.math.BigDecimal</code> and
* return the result of the <code>BigDecimal.rupareTo(BigDecimal)</code> method.
*
* As a consequence, the method is not suitable to implement a
* <code>java.util.ruparator</code> for numbers. To achieve this,
* one had to accept "not a number" arguments and place them somewhere
* in the row of numbers (probably at the upper end, i.e. larger than
* positive infinity, as <code>Double.rupare(double, double)</code>
* does it).
* So the behavior of this method is like that of the comparison
* operator for primitive types and not like that of the related
* <code>compareTo(...)</code> methods. Besides the handling of
* "not a number" values this makes a difference, when comparing
* the float or double values <code>-0.0</code> and <code>0.0</code>:
* again, like the operators, we consider them as equal (whereas
* according to <code>Double.rupareTo(...)</code> <code>-0.0</code>
* is less than <code>0.0</code>).
*
* @param first
* @param second
* @return int
* @throws ArithmeticException One or both of the given numbers is <code>null</code> or "not a number".
*/
public static int compare(Number first, Number second) throws ArithmeticException {
if (first == null || second == null || isNaN(first) || isNaN(second))
throw new ArithmeticException("Arguments must not be null or NaN.");
int result = -2;
if (isLongCompatible(first) && isLongCompatible(second)) {
long v1 = first.longValue(), v2 = second.longValue();
result = v1 < v2 ? -1 : v1 == v2 ? 0 : v1 > v2 ? 1 : 2;
} else if (isDoubleCompatible(first) && isDoubleCompatible(second)) {
double v1 = first.doubleValue(), v2 = second.doubleValue();
result = v1 < v2 ? -1 : v1 == v2 ? 0 : v1 > v2 ? 1 : 2;
}
if (result == 2) // should not happen
throw new ArithmeticException("Arguments " + first + " and " + second + " are not comparable.");
if (result > -2)
return result;
if (isInfinite(first)) // => second is finite
return first.doubleValue() == Double.NEGATIVE_INFINITY ? -1 : 1;
if (isInfinite(second)) // => first is finite
return second.doubleValue() == Double.POSITIVE_INFINITY ? -1 : 1;
return toBigDecimal(first).rupareTo(toBigDecimal(second));
}
}
Fraction is a Number implementation that stores fractions accurately.
/*
* 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 from Apache
import java.math.BigInteger;
/**
* <p><code>Fraction</code> is a <code>Number</code> implementation that
* stores fractions accurately.</p>
*
* <p>This class is immutable, and interoperable with most methods that accept
* a <code>Number</code>.</p>
*
* @author Travis Reeder
* @author Stephen Colebourne
* @author Tim O"Brien
* @author Pete Gieser
* @author C. Scott Ananian
* @since 2.0
* @version $Id: Fraction.java 599500 2007-11-29 16:25:54Z mbenson $
*/
public final class Fraction extends Number implements Comparable {
/**
* Required for serialization support. Lang version 2.0.
*
* @see java.io.Serializable
*/
private static final long serialVersionUID = 65382027393090L;
/**
* <code>Fraction</code> representation of 0.
*/
public static final Fraction ZERO = new Fraction(0, 1);
/**
* <code>Fraction</code> representation of 1.
*/
public static final Fraction ONE = new Fraction(1, 1);
/**
* <code>Fraction</code> representation of 1/2.
*/
public static final Fraction ONE_HALF = new Fraction(1, 2);
/**
* <code>Fraction</code> representation of 1/3.
*/
public static final Fraction ONE_THIRD = new Fraction(1, 3);
/**
* <code>Fraction</code> representation of 2/3.
*/
public static final Fraction TWO_THIRDS = new Fraction(2, 3);
/**
* <code>Fraction</code> representation of 1/4.
*/
public static final Fraction ONE_QUARTER = new Fraction(1, 4);
/**
* <code>Fraction</code> representation of 2/4.
*/
public static final Fraction TWO_QUARTERS = new Fraction(2, 4);
/**
* <code>Fraction</code> representation of 3/4.
*/
public static final Fraction THREE_QUARTERS = new Fraction(3, 4);
/**
* <code>Fraction</code> representation of 1/5.
*/
public static final Fraction ONE_FIFTH = new Fraction(1, 5);
/**
* <code>Fraction</code> representation of 2/5.
*/
public static final Fraction TWO_FIFTHS = new Fraction(2, 5);
/**
* <code>Fraction</code> representation of 3/5.
*/
public static final Fraction THREE_FIFTHS = new Fraction(3, 5);
/**
* <code>Fraction</code> representation of 4/5.
*/
public static final Fraction FOUR_FIFTHS = new Fraction(4, 5);
/**
* The numerator number part of the fraction (the three in three sevenths).
*/
private final int numerator;
/**
* The denominator number part of the fraction (the seven in three sevenths).
*/
private final int denominator;
/**
* Cached output hashCode (class is immutable).
*/
private transient int hashCode = 0;
/**
* Cached output toString (class is immutable).
*/
private transient String toString = null;
/**
* Cached output toProperString (class is immutable).
*/
private transient String toProperString = null;
/**
* <p>Constructs a <code>Fraction</code> instance with the 2 parts
* of a fraction Y/Z.</p>
*
* @param numerator the numerator, for example the three in "three sevenths"
* @param denominator the denominator, for example the seven in "three sevenths"
*/
private Fraction(int numerator, int denominator) {
super();
this.numerator = numerator;
this.denominator = denominator;
}
/**
* <p>Creates a <code>Fraction</code> instance with the 2 parts
* of a fraction Y/Z.</p>
*
* <p>Any negative signs are resolved to be on the numerator.</p>
*
* @param numerator the numerator, for example the three in "three sevenths"
* @param denominator the denominator, for example the seven in "three sevenths"
* @return a new fraction instance
* @throws ArithmeticException if the denomiator is <code>zero</code>
*/
public static Fraction getFraction(int numerator, int denominator) {
if (denominator == 0) {
throw new ArithmeticException("The denominator must not be zero");
}
if (denominator < 0) {
if (numerator==Integer.MIN_VALUE ||
denominator==Integer.MIN_VALUE) {
throw new ArithmeticException("overflow: can"t negate");
}
numerator = -numerator;
denominator = -denominator;
}
return new Fraction(numerator, denominator);
}
/**
* <p>Creates a <code>Fraction</code> instance with the 3 parts
* of a fraction X Y/Z.</p>
*
* <p>The negative sign must be passed in on the whole number part.</p>
*
* @param whole the whole number, for example the one in "one and three sevenths"
* @param numerator the numerator, for example the three in "one and three sevenths"
* @param denominator the denominator, for example the seven in "one and three sevenths"
* @return a new fraction instance
* @throws ArithmeticException if the denomiator is <code>zero</code>
* @throws ArithmeticException if the denominator is negative
* @throws ArithmeticException if the numerator is negative
* @throws ArithmeticException if the resulting numerator exceeds
* <code>Integer.MAX_VALUE</code>
*/
public static Fraction getFraction(int whole, int numerator, int denominator) {
if (denominator == 0) {
throw new ArithmeticException("The denominator must not be zero");
}
if (denominator < 0) {
throw new ArithmeticException("The denominator must not be negative");
}
if (numerator < 0) {
throw new ArithmeticException("The numerator must not be negative");
}
long numeratorValue;
if (whole < 0) {
numeratorValue = whole * (long)denominator - numerator;
} else {
numeratorValue = whole * (long)denominator + numerator;
}
if (numeratorValue < Integer.MIN_VALUE ||
numeratorValue > Integer.MAX_VALUE) {
throw new ArithmeticException("Numerator too large to represent as an Integer.");
}
return new Fraction((int) numeratorValue, denominator);
}
/**
* <p>Creates a reduced <code>Fraction</code> instance with the 2 parts
* of a fraction Y/Z.</p>
*
* <p>For example, if the input parameters represent 2/4, then the created
* fraction will be 1/2.</p>
*
* <p>Any negative signs are resolved to be on the numerator.</p>
*
* @param numerator the numerator, for example the three in "three sevenths"
* @param denominator the denominator, for example the seven in "three sevenths"
* @return a new fraction instance, with the numerator and denominator reduced
* @throws ArithmeticException if the denominator is <code>zero</code>
*/
public static Fraction getReducedFraction(int numerator, int denominator) {
if (denominator == 0) {
throw new ArithmeticException("The denominator must not be zero");
}
if (numerator==0) {
return ZERO; // normalize zero.
}
// allow 2^k/-2^31 as a valid fraction (where k>0)
if (denominator==Integer.MIN_VALUE && (numerator&1)==0) {
numerator/=2; denominator/=2;
}
if (denominator < 0) {
if (numerator==Integer.MIN_VALUE ||
denominator==Integer.MIN_VALUE) {
throw new ArithmeticException("overflow: can"t negate");
}
numerator = -numerator;
denominator = -denominator;
}
// simplify fraction.
int gcd = greatestCommonDivisor(numerator, denominator);
numerator /= gcd;
denominator /= gcd;
return new Fraction(numerator, denominator);
}
/**
* <p>Creates a <code>Fraction</code> instance from a <code>double</code> value.</p>
*
* <p>This method uses the , computing a maximum of
* 25 convergents and bounding the denominator by 10,000.</p>
*
* @param value the double value to convert
* @return a new fraction instance that is close to the value
* @throws ArithmeticException if <code>|value| > Integer.MAX_VALUE</code>
* or <code>value = NaN</code>
* @throws ArithmeticException if the calculated denominator is <code>zero</code>
* @throws ArithmeticException if the the algorithm does not converge
*/
public static Fraction getFraction(double value) {
int sign = (value < 0 ? -1 : 1);
value = Math.abs(value);
if (value > Integer.MAX_VALUE || Double.isNaN(value)) {
throw new ArithmeticException
("The value must not be greater than Integer.MAX_VALUE or NaN");
}
int wholeNumber = (int) value;
value -= wholeNumber;
int numer0 = 0; // the pre-previous
int denom0 = 1; // the pre-previous
int numer1 = 1; // the previous
int denom1 = 0; // the previous
int numer2 = 0; // the current, setup in calculation
int denom2 = 0; // the current, setup in calculation
int a1 = (int) value;
int a2 = 0;
double x1 = 1;
double x2 = 0;
double y1 = value - a1;
double y2 = 0;
double delta1, delta2 = Double.MAX_VALUE;
double fraction;
int i = 1;
// System.out.println("---");
do {
delta1 = delta2;
a2 = (int) (x1 / y1);
x2 = y1;
y2 = x1 - a2 * y1;
numer2 = a1 * numer1 + numer0;
denom2 = a1 * denom1 + denom0;
fraction = (double) numer2 / (double) denom2;
delta2 = Math.abs(value - fraction);
// System.out.println(numer2 + " " + denom2 + " " + fraction + " " + delta2 + " " + y1);
a1 = a2;
x1 = x2;
y1 = y2;
numer0 = numer1;
denom0 = denom1;
numer1 = numer2;
denom1 = denom2;
i++;
// System.out.println(">>" + delta1 +" "+ delta2+" "+(delta1 > delta2)+" "+i+" "+denom2);
} while ((delta1 > delta2) && (denom2 <= 10000) && (denom2 > 0) && (i < 25));
if (i == 25) {
throw new ArithmeticException("Unable to convert double to fraction");
}
return getReducedFraction((numer0 + wholeNumber * denom0) * sign, denom0);
}
/**
* <p>Creates a Fraction from a <code>String</code>.</p>
*
* <p>The formats accepted are:</p>
*
* <ol>
* <li><code>double</code> String containing a dot</li>
* <li>"X Y/Z"</li>
* <li>"Y/Z"</li>
* <li>"X" (a simple whole number)</li>
* </ol>
* and a .</p>
*
* @param str the string to parse, must not be <code>null</code>
* @return the new <code>Fraction</code> instance
* @throws IllegalArgumentException if the string is <code>null</code>
* @throws NumberFormatException if the number format is invalid
*/
public static Fraction getFraction(String str) {
if (str == null) {
throw new IllegalArgumentException("The string must not be null");
}
// parse double format
int pos = str.indexOf(".");
if (pos >= 0) {
return getFraction(Double.parseDouble(str));
}
// parse X Y/Z format
pos = str.indexOf(" ");
if (pos > 0) {
int whole = Integer.parseInt(str.substring(0, pos));
str = str.substring(pos + 1);
pos = str.indexOf("/");
if (pos < 0) {
throw new NumberFormatException("The fraction could not be parsed as the format X Y/Z");
} else {
int numer = Integer.parseInt(str.substring(0, pos));
int denom = Integer.parseInt(str.substring(pos + 1));
return getFraction(whole, numer, denom);
}
}
// parse Y/Z format
pos = str.indexOf("/");
if (pos < 0) {
// simple whole number
return getFraction(Integer.parseInt(str), 1);
} else {
int numer = Integer.parseInt(str.substring(0, pos));
int denom = Integer.parseInt(str.substring(pos + 1));
return getFraction(numer, denom);
}
}
// Accessors
//-------------------------------------------------------------------
/**
* <p>Gets the numerator part of the fraction.</p>
*
* <p>This method may return a value greater than the denominator, an
* improper fraction, such as the seven in 7/4.</p>
*
* @return the numerator fraction part
*/
public int getNumerator() {
return numerator;
}
/**
* <p>Gets the denominator part of the fraction.</p>
*
* @return the denominator fraction part
*/
public int getDenominator() {
return denominator;
}
/**
* <p>Gets the proper numerator, always positive.</p>
*
* <p>An improper fraction 7/4 can be resolved into a proper one, 1 3/4.
* This method returns the 3 from the proper fraction.</p>
*
* <p>If the fraction is negative such as -7/4, it can be resolved into
* -1 3/4, so this method returns the positive proper numerator, 3.</p>
*
* @return the numerator fraction part of a proper fraction, always positive
*/
public int getProperNumerator() {
return Math.abs(numerator % denominator);
}
/**
* <p>Gets the proper whole part of the fraction.</p>
*
* <p>An improper fraction 7/4 can be resolved into a proper one, 1 3/4.
* This method returns the 1 from the proper fraction.</p>
*
* <p>If the fraction is negative such as -7/4, it can be resolved into
* -1 3/4, so this method returns the positive whole part -1.</p>
*
* @return the whole fraction part of a proper fraction, that includes the sign
*/
public int getProperWhole() {
return numerator / denominator;
}
// Number methods
//-------------------------------------------------------------------
/**
* <p>Gets the fraction as an <code>int</code>. This returns the whole number
* part of the fraction.</p>
*
* @return the whole number fraction part
*/
public int intValue() {
return numerator / denominator;
}
/**
* <p>Gets the fraction as a <code>long</code>. This returns the whole number
* part of the fraction.</p>
*
* @return the whole number fraction part
*/
public long longValue() {
return (long) numerator / denominator;
}
/**
* <p>Gets the fraction as a <code>float</code>. This calculates the fraction
* as the numerator divided by denominator.</p>
*
* @return the fraction as a <code>float</code>
*/
public float floatValue() {
return ((float) numerator) / ((float) denominator);
}
/**
* <p>Gets the fraction as a <code>double</code>. This calculates the fraction
* as the numerator divided by denominator.</p>
*
* @return the fraction as a <code>double</code>
*/
public double doubleValue() {
return ((double) numerator) / ((double) denominator);
}
// Calculations
//-------------------------------------------------------------------
/**
* <p>Reduce the fraction to the smallest values for the numerator and
* denominator, returning the result.</p>
*
* <p>For example, if this fraction represents 2/4, then the result
* will be 1/2.</p>
*
* @return a new reduced fraction instance, or this if no simplification possible
*/
public Fraction reduce() {
if (numerator == 0) {
return equals(ZERO) ? this : ZERO;
}
int gcd = greatestCommonDivisor(Math.abs(numerator), denominator);
if (gcd == 1) {
return this;
}
return Fraction.getFraction(numerator / gcd, denominator / gcd);
}
/**
* <p>Gets a fraction that is the inverse (1/fraction) of this one.</p>
*
* <p>The returned fraction is not reduced.</p>
*
* @return a new fraction instance with the numerator and denominator
* inverted.
* @throws ArithmeticException if the fraction represents zero.
*/
public Fraction invert() {
if (numerator == 0) {
throw new ArithmeticException("Unable to invert zero.");
}
if (numerator==Integer.MIN_VALUE) {
throw new ArithmeticException("overflow: can"t negate numerator");
}
if (numerator<0) {
return new Fraction(-denominator, -numerator);
} else {
return new Fraction(denominator, numerator);
}
}
/**
* <p>Gets a fraction that is the negative (-fraction) of this one.</p>
*
* <p>The returned fraction is not reduced.</p>
*
* @return a new fraction instance with the opposite signed numerator
*/
public Fraction negate() {
// the positive range is one smaller than the negative range of an int.
if (numerator==Integer.MIN_VALUE) {
throw new ArithmeticException("overflow: too large to negate");
}
return new Fraction(-numerator, denominator);
}
/**
* <p>Gets a fraction that is the positive equivalent of this one.</p>
* <p>More precisely: <code>(fraction >= 0 ? this : -fraction)</code></p>
*
* <p>The returned fraction is not reduced.</p>
*
* @return <code>this</code> if it is positive, or a new positive fraction
* instance with the opposite signed numerator
*/
public Fraction abs() {
if (numerator >= 0) {
return this;
}
return negate();
}
/**
* <p>Gets a fraction that is raised to the passed in power.</p>
*
* <p>The returned fraction is in reduced form.</p>
*
* @param power the power to raise the fraction to
* @return <code>this</code> if the power is one, <code>ONE</code> if the power
* is zero (even if the fraction equals ZERO) or a new fraction instance
* raised to the appropriate power
* @throws ArithmeticException if the resulting numerator or denominator exceeds
* <code>Integer.MAX_VALUE</code>
*/
public Fraction pow(int power) {
if (power == 1) {
return this;
} else if (power == 0) {
return ONE;
} else if (power < 0) {
if (power==Integer.MIN_VALUE) { // MIN_VALUE can"t be negated.
return this.invert().pow(2).pow(-(power/2));
}
return this.invert().pow(-power);
} else {
Fraction f = this.multiplyBy(this);
if ((power % 2) == 0) { // if even...
return f.pow(power/2);
} else { // if odd...
return f.pow(power/2).multiplyBy(this);
}
}
}
/**
* <p>Gets the greatest common divisor of the absolute value of
* two numbers, using the "binary gcd" method which avoids
* division and modulo operations. See Knuth 4.5.2 algorithm B.
* This algorithm is due to Josef Stein (1961).</p>
*
* @param u a non-zero number
* @param v a non-zero number
* @return the greatest common divisor, never zero
*/
private static int greatestCommonDivisor(int u, int v) {
//if either op. is abs 0 or 1, return 1:
if (Math.abs(u) <= 1 || Math.abs(v) <= 1) {
return 1;
}
// keep u and v negative, as negative integers range down to
// -2^31, while positive numbers can only be as large as 2^31-1
// (i.e. we can"t necessarily negate a negative number without
// overflow)
if (u>0) { u=-u; } // make u negative
if (v>0) { v=-v; } // make v negative
// B1. [Find power of 2]
int k=0;
while ((u&1)==0 && (v&1)==0 && k<31) { // while u and v are both even...
u/=2; v/=2; k++; // cast out twos.
}
if (k==31) {
throw new ArithmeticException("overflow: gcd is 2^31");
}
// B2. Initialize: u and v have been divided by 2^k and at least
// one is odd.
int t = ((u&1)==1) ? v : -(u/2)/*B3*/;
// t negative: u was odd, v may be even (t replaces v)
// t positive: u was even, v is odd (t replaces u)
do {
/* assert u<0 && v<0; */
// B4/B3: cast out twos from t.
while ((t&1)==0) { // while t is even..
t/=2; // cast out twos
}
// B5 [reset max(u,v)]
if (t>0) {
u = -t;
} else {
v = t;
}
// B6/B3. at this point both u and v should be odd.
t = (v - u)/2;
// |u| larger: t positive (replace u)
// |v| larger: t negative (replace v)
} while (t!=0);
return -u*(1<<k); // gcd is u*2^k
}
// Arithmetic
//-------------------------------------------------------------------
/**
* Multiply two integers, checking for overflow.
*
* @param x a factor
* @param y a factor
* @return the product <code>x*y</code>
* @throws ArithmeticException if the result can not be represented as
* an int
*/
private static int mulAndCheck(int x, int y) {
long m = ((long)x)*((long)y);
if (m < Integer.MIN_VALUE ||
m > Integer.MAX_VALUE) {
throw new ArithmeticException("overflow: mul");
}
return (int)m;
}
/**
* Multiply two non-negative integers, checking for overflow.
*
* @param x a non-negative factor
* @param y a non-negative factor
* @return the product <code>x*y</code>
* @throws ArithmeticException if the result can not be represented as
* an int
*/
private static int mulPosAndCheck(int x, int y) {
/* assert x>=0 && y>=0; */
long m = ((long)x)*((long)y);
if (m > Integer.MAX_VALUE) {
throw new ArithmeticException("overflow: mulPos");
}
return (int)m;
}
/**
* Add two integers, checking for overflow.
*
* @param x an addend
* @param y an addend
* @return the sum <code>x+y</code>
* @throws ArithmeticException if the result can not be represented as
* an int
*/
private static int addAndCheck(int x, int y) {
long s = (long)x+(long)y;
if (s < Integer.MIN_VALUE ||
s > Integer.MAX_VALUE) {
throw new ArithmeticException("overflow: add");
}
return (int)s;
}
/**
* Subtract two integers, checking for overflow.
*
* @param x the minuend
* @param y the subtrahend
* @return the difference <code>x-y</code>
* @throws ArithmeticException if the result can not be represented as
* an int
*/
private static int subAndCheck(int x, int y) {
long s = (long)x-(long)y;
if (s < Integer.MIN_VALUE ||
s > Integer.MAX_VALUE) {
throw new ArithmeticException("overflow: add");
}
return (int)s;
}
/**
* <p>Adds the value of this fraction to another, returning the result in reduced form.
* The algorithm follows Knuth, 4.5.1.</p>
*
* @param fraction the fraction to add, must not be <code>null</code>
* @return a <code>Fraction</code> instance with the resulting values
* @throws IllegalArgumentException if the fraction is <code>null</code>
* @throws ArithmeticException if the resulting numerator or denominator exceeds
* <code>Integer.MAX_VALUE</code>
*/
public Fraction add(Fraction fraction) {
return addSub(fraction, true /* add */);
}
/**
* <p>Subtracts the value of another fraction from the value of this one,
* returning the result in reduced form.</p>
*
* @param fraction the fraction to subtract, must not be <code>null</code>
* @return a <code>Fraction</code> instance with the resulting values
* @throws IllegalArgumentException if the fraction is <code>null</code>
* @throws ArithmeticException if the resulting numerator or denominator
* cannot be represented in an <code>int</code>.
*/
public Fraction subtract(Fraction fraction) {
return addSub(fraction, false /* subtract */);
}
/**
* Implement add and subtract using algorithm described in Knuth 4.5.1.
*
* @param fraction the fraction to subtract, must not be <code>null</code>
* @param isAdd true to add, false to subtract
* @return a <code>Fraction</code> instance with the resulting values
* @throws IllegalArgumentException if the fraction is <code>null</code>
* @throws ArithmeticException if the resulting numerator or denominator
* cannot be represented in an <code>int</code>.
*/
private Fraction addSub(Fraction fraction, boolean isAdd) {
if (fraction == null) {
throw new IllegalArgumentException("The fraction must not be null");
}
// zero is identity for addition.
if (numerator == 0) {
return isAdd ? fraction : fraction.negate();
}
if (fraction.numerator == 0) {
return this;
}
// if denominators are randomly distributed, d1 will be 1 about 61%
// of the time.
int d1 = greatestCommonDivisor(denominator, fraction.denominator);
if (d1==1) {
// result is ( (u*v" +/- u"v) / u"v")
int uvp = mulAndCheck(numerator, fraction.denominator);
int upv = mulAndCheck(fraction.numerator, denominator);
return new Fraction
(isAdd ? addAndCheck(uvp, upv) : subAndCheck(uvp, upv),
mulPosAndCheck(denominator, fraction.denominator));
}
// the quantity "t" requires 65 bits of precision; see knuth 4.5.1
// exercise 7. we"re going to use a BigInteger.
// t = u(v"/d1) +/- v(u"/d1)
BigInteger uvp = BigInteger.valueOf(numerator)
.multiply(BigInteger.valueOf(fraction.denominator/d1));
BigInteger upv = BigInteger.valueOf(fraction.numerator)
.multiply(BigInteger.valueOf(denominator/d1));
BigInteger t = isAdd ? uvp.add(upv) : uvp.subtract(upv);
// but d2 doesn"t need extra precision because
// d2 = gcd(t,d1) = gcd(t mod d1, d1)
int tmodd1 = t.mod(BigInteger.valueOf(d1)).intValue();
int d2 = (tmodd1==0)?d1:greatestCommonDivisor(tmodd1, d1);
// result is (t/d2) / (u"/d1)(v"/d2)
BigInteger w = t.divide(BigInteger.valueOf(d2));
if (w.bitLength() > 31) {
throw new ArithmeticException
("overflow: numerator too large after multiply");
}
return new Fraction
(w.intValue(),
mulPosAndCheck(denominator/d1, fraction.denominator/d2));
}
/**
* <p>Multiplies the value of this fraction by another, returning the
* result in reduced form.</p>
*
* @param fraction the fraction to multiply by, must not be <code>null</code>
* @return a <code>Fraction</code> instance with the resulting values
* @throws IllegalArgumentException if the fraction is <code>null</code>
* @throws ArithmeticException if the resulting numerator or denominator exceeds
* <code>Integer.MAX_VALUE</code>
*/
public Fraction multiplyBy(Fraction fraction) {
if (fraction == null) {
throw new IllegalArgumentException("The fraction must not be null");
}
if (numerator == 0 || fraction.numerator == 0) {
return ZERO;
}
// knuth 4.5.1
// make sure we don"t overflow unless the result *must* overflow.
int d1 = greatestCommonDivisor(numerator, fraction.denominator);
int d2 = greatestCommonDivisor(fraction.numerator, denominator);
return getReducedFraction
(mulAndCheck(numerator/d1, fraction.numerator/d2),
mulPosAndCheck(denominator/d2, fraction.denominator/d1));
}
/**
* <p>Divide the value of this fraction by another.</p>
*
* @param fraction the fraction to divide by, must not be <code>null</code>
* @return a <code>Fraction</code> instance with the resulting values
* @throws IllegalArgumentException if the fraction is <code>null</code>
* @throws ArithmeticException if the fraction to divide by is zero
* @throws ArithmeticException if the resulting numerator or denominator exceeds
* <code>Integer.MAX_VALUE</code>
*/
public Fraction divideBy(Fraction fraction) {
if (fraction == null) {
throw new IllegalArgumentException("The fraction must not be null");
}
if (fraction.numerator == 0) {
throw new ArithmeticException("The fraction to divide by must not be zero");
}
return multiplyBy(fraction.invert());
}
// Basics
//-------------------------------------------------------------------
/**
* <p>Compares this fraction to another object to test if they are equal.</p>.
*
* <p>To be equal, both values must be equal. Thus 2/4 is not equal to 1/2.</p>
*
* @param obj the reference object with which to compare
* @return <code>true</code> if this object is equal
*/
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (obj instanceof Fraction == false) {
return false;
}
Fraction other = (Fraction) obj;
return (getNumerator() == other.getNumerator() &&
getDenominator() == other.getDenominator());
}
/**
* <p>Gets a hashCode for the fraction.</p>
*
* @return a hash code value for this object
*/
public int hashCode() {
if (hashCode == 0) {
// hashcode update should be atomic.
hashCode = 37 * (37 * 17 + getNumerator()) + getDenominator();
}
return hashCode;
}
/**
* <p>Compares this object to another based on size.</p>
*
* <p>Note: this class has a natural ordering that is inconsistent
* with equals, because, for example, equals treats 1/2 and 2/4 as
* different, whereas compareTo treats them as equal.
*
* @param object the object to compare to
* @return -1 if this is less, 0 if equal, +1 if greater
* @throws ClassCastException if the object is not a <code>Fraction</code>
* @throws NullPointerException if the object is <code>null</code>
*/
public int compareTo(Object object) {
Fraction other = (Fraction) object;
if (this==other) {
return 0;
}
if (numerator == other.numerator && denominator == other.denominator) {
return 0;
}
// otherwise see which is less
long first = (long) numerator * (long) other.denominator;
long second = (long) other.numerator * (long) denominator;
if (first == second) {
return 0;
} else if (first < second) {
return -1;
} else {
return 1;
}
}
/**
* <p>Gets the fraction as a <code>String</code>.</p>
*
* <p>The format used is "<i>numerator</i>/<i>denominator</i>" always.
*
* @return a <code>String</code> form of the fraction
*/
public String toString() {
if (toString == null) {
toString = new StringBuffer(32)
.append(getNumerator())
.append("/")
.append(getDenominator()).toString();
}
return toString;
}
/**
* <p>Gets the fraction as a proper <code>String</code> in the format X Y/Z.</p>
*
* <p>The format used in "<i>wholeNumber</i> <i>numerator</i>/<i>denominator</i>".
* If the whole number is zero it will be ommitted. If the numerator is zero,
* only the whole number is returned.</p>
*
* @return a <code>String</code> form of the fraction
*/
public String toProperString() {
if (toProperString == null) {
if (numerator == 0) {
toProperString = "0";
} else if (numerator == denominator) {
toProperString = "1";
} else if (numerator == -1 * denominator) {
toProperString = "-1";
} else if ((numerator>0?-numerator:numerator) < -denominator) {
// note that we do the magnitude comparison test above with
// NEGATIVE (not positive) numbers, since negative numbers
// have a larger range. otherwise numerator==Integer.MIN_VALUE
// is handled incorrectly.
int properNumerator = getProperNumerator();
if (properNumerator == 0) {
toProperString = Integer.toString(getProperWhole());
} else {
toProperString = new StringBuffer(32)
.append(getProperWhole()).append(" ")
.append(properNumerator).append("/")
.append(getDenominator()).toString();
}
} else {
toProperString = new StringBuffer(32)
.append(getNumerator()).append("/")
.append(getDenominator()).toString();
}
}
return toProperString;
}
}
Represents a range of Number objects.
/*
* 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.
*/
/**
* <p>Represents a range of {@link Number} objects.</p>
*
* <p>This class uses <code>double</code> comparisons. This means that it
* is unsuitable for dealing with large <code>Long</code>, <code>BigDecimal</code>
* or <code>BigInteger</code> numbers.</p>
*
* @author
* @author Stephen Colebourne
* @since 1.0
* @version $Revision: 437554 $ $Date: 2006-08-27 23:21:41 -0700 (Sun, 27 Aug 2006) $
*
*
*/
public final class NumberRange {
/* The minimum number in this range. */
private final Number min;
/* The maximum number in this range. */
private final Number max;
/**
* <p>Constructs a new <code>NumberRange</code> using
* <code>number</code> as both the minimum and maximum in
* this range.</p>
*
* @param num the number to use for this range
* @throws NullPointerException if the number is <code>null</code>
*/
public NumberRange(Number num) {
if (num == null) {
throw new NullPointerException("The number must not be null");
}
this.min = num;
this.max = num;
}
/**
* <p>Constructs a new <code>NumberRange</code> with the specified
* minimum and maximum numbers.</p>
*
* <p><em>If the maximum is less than the minimum, the range will be constructed
* from the minimum value to the minimum value, not what you would expect!.</em></p>
*
* @param min the minimum number in this range
* @param max the maximum number in this range
* @throws NullPointerException if either the minimum or maximum number is
* <code>null</code>
*/
public NumberRange(Number min, Number max) {
if (min == null) {
throw new NullPointerException("The minimum value must not be null");
} else if (max == null) {
throw new NullPointerException("The maximum value must not be null");
}
if (max.doubleValue() < min.doubleValue()) {
this.min = this.max = min;
} else {
this.min = min;
this.max = max;
}
}
/**
* <p>Returns the minimum number in this range.</p>
*
* @return the minimum number in this range
*/
public Number getMinimum() {
return min;
}
/**
* <p>Returns the maximum number in this range.</p>
*
* @return the maximum number in this range
*/
public Number getMaximum() {
return max;
}
/**
* <p>Tests whether the specified <code>number</code> occurs within
* this range using <code>double</code> comparison.</p>
*
* @param number the number to test
* @return <code>true</code> if the specified number occurs within this
* range; otherwise, <code>false</code>
*/
public boolean includesNumber(Number number) {
if (number == null) {
return false;
} else {
return !(min.doubleValue() > number.doubleValue()) &&
!(max.doubleValue() < number.doubleValue());
}
}
/**
* <p>Tests whether the specified range occurs entirely within this
* range using <code>double</code> comparison.</p>
*
* @param range the range to test
* @return <code>true</code> if the specified range occurs entirely within
* this range; otherwise, <code>false</code>
*/
public boolean includesRange(NumberRange range) {
if (range == null) {
return false;
} else {
return includesNumber(range.min) && includesNumber(range.max);
}
}
/**
* <p>Tests whether the specified range overlaps with this range
* using <code>double</code> comparison.</p>
*
* @param range the range to test
* @return <code>true</code> if the specified range overlaps with this
* range; otherwise, <code>false</code>
*/
public boolean overlaps(NumberRange range) {
if (range == null) {
return false;
} else {
return range.includesNumber(min) || range.includesNumber(max) ||
includesRange(range);
}
}
/**
* <p>Indicates whether some other <code>Object</code> is
* "equal" to this one.</p>
*
* @param obj the reference object with which to compare
* @return <code>true</code> if this object is the same as the obj
* argument; <code>false</code> otherwise
*/
public boolean equals(Object obj) {
if (obj == this) {
return true;
} else if (!(obj instanceof NumberRange)) {
return false;
} else {
NumberRange range = (NumberRange)obj;
return min.equals(range.min) && max.equals(range.max);
}
}
/**
* <p>Returns a hash code value for this object.</p>
*
* @return a hash code value for this object
*/
public int hashCode() {
int result = 17;
result = 37 * result + min.hashCode();
result = 37 * result + max.hashCode();
return result;
}
/**
* <p>Returns the string representation of this range.</p>
*
* <p>This string is the string representation of the minimum and
* maximum numbers in the range, separated by a hyphen. If a number
* is negative, then it is enclosed in parentheses.</p>
*
* @return the string representation of this range
*/
public String toString() {
StringBuffer sb = new StringBuffer();
if (min.doubleValue() < 0) {
sb.append("(")
.append(min)
.append(")");
} else {
sb.append(min);
}
sb.append("-");
if (max.doubleValue() < 0) {
sb.append("(")
.append(max)
.append(")");
} else {
sb.append(max);
}
return sb.toString();
}
}
Turns a string value into a java.lang.Number.
import java.math.BigDecimal;
import java.math.BigInteger;
/**
* 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.
*/
/**
* Contains useful helper methods for classes within this package.
*
* @author John Keyes (john at integralsource.ru)
* @version $Revision: 680644 $, $Date: 2008-07-29 01:13:48 -0700 (Tue, 29 Jul 2008) $
*/
public class Main {
//--------------------------------------------------------------------
// must handle Long, Float, Integer, Float, Short,
// BigDecimal, BigInteger and Byte
// useful methods:
// Byte.decode(String)
// Byte.valueOf(String,int radix)
// Byte.valueOf(String)
// Double.valueOf(String)
// Float.valueOf(String)
// new Float(String)
// Integer.valueOf(String,int radix)
// Integer.valueOf(String)
// Integer.decode(String)
// Integer.getInteger(String)
// Integer.getInteger(String,int val)
// Integer.getInteger(String,Integer val)
// new Integer(String)
// new Double(String)
// new Byte(String)
// new Long(String)
// Long.getLong(String)
// Long.getLong(String,int)
// Long.getLong(String,Integer)
// Long.valueOf(String,int)
// Long.valueOf(String)
// new Short(String)
// Short.decode(String)
// Short.valueOf(String,int)
// Short.valueOf(String)
// new BigDecimal(String)
// new BigInteger(String)
// new BigInteger(String,int radix)
// Possible inputs:
// 45 45.5 45E7 4.5E7 Hex Oct Binary xxxF xxxD xxxf xxxd
// plus minus everything. Prolly more. A lot are not separable.
/**
* <p>Turns a string value into a java.lang.Number.</p>
*
* <p>First, the value is examined for a type qualifier on the end
* (<code>"f","F","d","D","l","L"</code>). If it is found, it starts
* trying to create successively larger types from the type specified
* until one is found that can hold the value.</p>
*
* <p>If a type specifier is not found, it will check for a decimal point
* and then try successively larger types from <code>Integer</code> to
* <code>BigInteger</code> and from <code>Float</code> to
* <code>BigDecimal</code>.</p>
*
* <p>If the string starts with <code>0x</code> or <code>-0x</code>, it
* will be interpreted as a hexadecimal integer. Values with leading
* <code>0</code>"s will not be interpreted as octal.</p>
*
* @param val String containing a number
* @return Number created from the string
* @throws NumberFormatException if the value cannot be converted
*/
public static Number createNumber(String val) throws NumberFormatException {
if (val == null) {
return null;
}
if (val.length() == 0) {
throw new NumberFormatException("\"\" is not a valid number.");
}
if (val.startsWith("--")) {
// this is protection for poorness in java.lang.BigDecimal.
// it accepts this as a legal value, but it does not appear
// to be in specification of class. OS X Java parses it to
// a wrong value.
return null;
}
if (val.startsWith("0x") || val.startsWith("-0x")) {
return createInteger(val);
}
char lastChar = val.charAt(val.length() - 1);
String mant;
String dec;
String exp;
int decPos = val.indexOf(".");
int expPos = val.indexOf("e") + val.indexOf("E") + 1;
if (decPos > -1) {
if (expPos > -1) {
if (expPos < decPos) {
throw new NumberFormatException(val + " is not a valid number.");
}
dec = val.substring(decPos + 1, expPos);
} else {
dec = val.substring(decPos + 1);
}
mant = val.substring(0, decPos);
} else {
if (expPos > -1) {
mant = val.substring(0, expPos);
} else {
mant = val;
}
dec = null;
}
if (!Character.isDigit(lastChar)) {
if (expPos > -1 && expPos < val.length() - 1) {
exp = val.substring(expPos + 1, val.length() - 1);
} else {
exp = null;
}
//Requesting a specific type..
String numeric = val.substring(0, val.length() - 1);
boolean allZeros = isAllZeros(mant) && isAllZeros(exp);
switch (lastChar) {
case "l" :
case "L" :
if (dec == null
&& exp == null
&& (numeric.charAt(0) == "-" && isDigits(numeric.substring(1)) || isDigits(numeric))) {
try {
return createLong(numeric);
} catch (NumberFormatException nfe) {
//Too big for a long
}
return createBigInteger(numeric);
}
throw new NumberFormatException(val + " is not a valid number.");
case "f" :
case "F" :
try {
Float f = createFloat(numeric);
if (!(f.isInfinite() || (f.floatValue() == 0.0F && !allZeros))) {
//If it"s too big for a float or the float value = 0 and the string
//has non-zeros in it, then float does not have the precision we want
return f;
}
} catch (NumberFormatException e) {
// ignore the bad number
}
//Fall through
case "d" :
case "D" :
try {
Double d = createDouble(numeric);
if (!(d.isInfinite() || (d.floatValue() == 0.0D && !allZeros))) {
return d;
}
} catch (NumberFormatException nfe) {
// empty catch
}
try {
return createBigDecimal(numeric);
} catch (NumberFormatException e) {
// empty catch
}
//Fall through
default :
throw new NumberFormatException(val + " is not a valid number.");
}
} else {
//User doesn"t have a preference on the return type, so let"s start
//small and go from there...
if (expPos > -1 && expPos < val.length() - 1) {
exp = val.substring(expPos + 1, val.length());
} else {
exp = null;
}
if (dec == null && exp == null) {
//Must be an int,long,bigint
try {
return createInteger(val);
} catch (NumberFormatException nfe) {
// empty catch
}
try {
return createLong(val);
} catch (NumberFormatException nfe) {
// empty catch
}
return createBigInteger(val);
} else {
//Must be a float,double,BigDec
boolean allZeros = isAllZeros(mant) && isAllZeros(exp);
try {
Float f = createFloat(val);
if (!(f.isInfinite() || (f.floatValue() == 0.0F && !allZeros))) {
return f;
}
} catch (NumberFormatException nfe) {
// empty catch
}
try {
Double d = createDouble(val);
if (!(d.isInfinite() || (d.doubleValue() == 0.0D && !allZeros))) {
return d;
}
} catch (NumberFormatException nfe) {
// empty catch
}
return createBigDecimal(val);
}
}
}
/**
* <p>Utility method for {@link #createNumber(java.lang.String)}.</p>
*
* <p>Returns <code>true</code> if s is <code>null</code>.</p>
*
* @param s the String to check
* @return if it is all zeros or <code>null</code>
*/
private static boolean isAllZeros(String s) {
if (s == null) {
return true;
}
for (int i = s.length() - 1; i >= 0; i--) {
if (s.charAt(i) != "0") {
return false;
}
}
return s.length() > 0;
}
//--------------------------------------------------------------------
/**
* <p>Convert a <code>String</code> to a <code>Float</code>.</p>
*
* @param val a <code>String</code> to convert
* @return converted <code>Float</code>
* @throws NumberFormatException if the value cannot be converted
*/
public static Float createFloat(String val) {
return Float.valueOf(val);
}
/**
* <p>Convert a <code>String</code> to a <code>Double</code>.</p>
*
* @param val a <code>String</code> to convert
* @return converted <code>Double</code>
* @throws NumberFormatException if the value cannot be converted
*/
public static Double createDouble(String val) {
return Double.valueOf(val);
}
/**
* <p>Convert a <code>String</code> to a <code>Integer</code>, handling
* hex and octal notations.</p>
*
* @param val a <code>String</code> to convert
* @return converted <code>Integer</code>
* @throws NumberFormatException if the value cannot be converted
*/
public static Integer createInteger(String val) {
// decode() handles 0xAABD and 0777 (hex and octal) as well.
return Integer.decode(val);
}
/**
* <p>Convert a <code>String</code> to a <code>Long</code>.</p>
*
* @param val a <code>String</code> to convert
* @return converted <code>Long</code>
* @throws NumberFormatException if the value cannot be converted
*/
public static Long createLong(String val) {
return Long.valueOf(val);
}
/**
* <p>Convert a <code>String</code> to a <code>BigInteger</code>.</p>
*
* @param val a <code>String</code> to convert
* @return converted <code>BigInteger</code>
* @throws NumberFormatException if the value cannot be converted
*/
public static BigInteger createBigInteger(String val) {
BigInteger bi = new BigInteger(val);
return bi;
}
/**
* <p>Convert a <code>String</code> to a <code>BigDecimal</code>.</p>
*
* @param val a <code>String</code> to convert
* @return converted <code>BigDecimal</code>
* @throws NumberFormatException if the value cannot be converted
*/
public static BigDecimal createBigDecimal(String val) {
BigDecimal bd = new BigDecimal(val);
return bd;
}
//--------------------------------------------------------------------
/**
* <p>Checks whether the <code>String</code> contains only
* digit characters.</p>
*
* <p><code>Null</code> and empty String will return
* <code>false</code>.</p>
*
* @param str the <code>String</code> to check
* @return <code>true</code> if str contains only unicode numeric
*/
public static boolean isDigits(String str) {
if ((str == null) || (str.length() == 0)) {
return false;
}
for (int i = 0; i < str.length(); i++) {
if (!Character.isDigit(str.charAt(i))) {
return false;
}
}
return true;
}
}
