Java/Language Basics/Java Beans — различия между версиями
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Текущая версия на 06:47, 1 июня 2010
Содержание
- 1 A JTable subclass that displays a table of the JavaBeans properties of any specified class
- 2 BeanContext Child Support
- 3 BeanContext Support
- 4 Creates all of the objects, a tests the service capabilities
- 5 Demonstration of set functionality in beans
- 6 How to create Java bean component
- 7 how to use the instantiateChild() convenience method to create a bean automatically nested into a bean context
- 8 illustrate delivery of the BeanContextMembershipEvent
- 9 Simple Java bean container
- 10 Use assert the verify value
A JTable subclass that displays a table of the JavaBeans properties of any specified class
/*
* Copyright (c) 2004 David Flanagan. All rights reserved.
* This code is from the book Java Examples in a Nutshell, 3nd Edition.
* It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
* You may study, use, and modify it for any non-commercial purpose,
* including teaching and use in open-source projects.
* You may distribute it non-commercially as long as you retain this notice.
* For a commercial use license, or to purchase the book,
* please visit http://www.davidflanagan.ru/javaexamples3.
*/
//package je3.gui;
import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.util.Arrays;
import java.util.ruparator;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.SwingConstants;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.TableColumn;
import javax.swing.table.TableColumnModel;
/**
* This class is a JTable subclass that displays a table of the JavaBeans
* properties of any specified class.
*/
public class PropertyTableJavaBean extends JTable {
/** This main method allows the class to be demonstrated standalone */
public static void main(String[] args) {
// Specify the name of the class as a command-line argument
Class beanClass = null;
try {
// Use reflection to get the Class from the classname
beanClass = new JButton().getClass();
} catch (Exception e) { // Report errors
System.out.println("Can"t find specified class: " + e.getMessage());
System.out.println("Usage: java PropertyTableJavaBean <bean class name>");
System.exit(0);
}
// Create a table to display the properties of the specified class
JTable table = new PropertyTableJavaBean(beanClass);
// Then put the table in a scrolling window, put the scrolling
// window into a frame, and pop it all up on to the screen
JScrollPane scrollpane = new JScrollPane(table);
JFrame frame = new JFrame("Properties of JavaBean: ");
frame.getContentPane().add(scrollpane);
frame.setSize(500, 400);
frame.setVisible(true);
}
/**
* This constructor method specifies what data the table will display (the
* table model) and uses the TableColumnModel to customize the way that the
* table displays it. The hard work is done by the TableModel implementation
* below.
*/
public PropertyTableJavaBean(Class beanClass) {
// Set the data model for this table
try {
setModel(new JavaBeanPropertyTableModel(beanClass));
} catch (IntrospectionException e) {
System.err.println("WARNING: can"t introspect: " + beanClass);
}
// Tweak the appearance of the table by manipulating its column model
TableColumnModel colmodel = getColumnModel();
// Set column widths
colmodel.getColumn(0).setPreferredWidth(125);
colmodel.getColumn(1).setPreferredWidth(200);
colmodel.getColumn(2).setPreferredWidth(75);
colmodel.getColumn(3).setPreferredWidth(50);
// Right justify the text in the first column
TableColumn namecol = colmodel.getColumn(0);
DefaultTableCellRenderer renderer = new DefaultTableCellRenderer();
renderer.setHorizontalAlignment(SwingConstants.RIGHT);
namecol.setCellRenderer(renderer);
}
/**
* This class implements TableModel and represents JavaBeans property data in
* a way that the JTable component can display. If you"ve got some type of
* tabular data to display, implement a TableModel class to describe that
* data, and the JTable component will be able to display it.
*/
static class JavaBeanPropertyTableModel extends AbstractTableModel {
PropertyDescriptor[] properties; // The properties to display
/**
* The constructor: use the JavaBeans introspector mechanism to get
* information about all the properties of a bean. Once we"ve got this
* information, the other methods will interpret it for JTable.
*/
public JavaBeanPropertyTableModel(Class beanClass) throws java.beans.IntrospectionException {
// Use the introspector class to get "bean info" about the class.
BeanInfo beaninfo = Introspector.getBeanInfo(beanClass);
// Get the property descriptors from that BeanInfo class
properties = beaninfo.getPropertyDescriptors();
// Now do a case-insensitive sort by property name
// The anonymous Comparator implementation specifies how to
// sort PropertyDescriptor objects by name
Arrays.sort(properties, new Comparator() {
public int compare(Object p, Object q) {
PropertyDescriptor a = (PropertyDescriptor) p;
PropertyDescriptor b = (PropertyDescriptor) q;
return a.getName().rupareToIgnoreCase(b.getName());
}
public boolean equals(Object o) {
return o == this;
}
});
}
// These are the names of the columns represented by this TableModel
static final String[] columnNames = new String[] { "Name", "Type", "Access", "Bound" };
// These are the types of the columns represented by this TableModel
static final Class[] columnTypes = new Class[] { String.class, Class.class, String.class,
Boolean.class };
// These simple methods return basic information about the table
public int getColumnCount() {
return columnNames.length;
}
public int getRowCount() {
return properties.length;
}
public String getColumnName(int column) {
return columnNames[column];
}
public Class getColumnClass(int column) {
return columnTypes[column];
}
/**
* This method returns the value that appears at the specified row and
* column of the table
*/
public Object getValueAt(int row, int column) {
PropertyDescriptor prop = properties[row];
switch (column) {
case 0:
return prop.getName();
case 1:
return prop.getPropertyType();
case 2:
return getAccessType(prop);
case 3:
return new Boolean(prop.isBound());
default:
return null;
}
}
// A helper method called from getValueAt() above
String getAccessType(PropertyDescriptor prop) {
java.lang.reflect.Method reader = prop.getReadMethod();
java.lang.reflect.Method writer = prop.getWriteMethod();
if ((reader != null) && (writer != null))
return "Read/Write";
else if (reader != null)
return "Read-Only";
else if (writer != null)
return "Write-Only";
else
return "No Access"; // should never happen
}
}
}
BeanContext Child Support
/*
* Copyright (c) 1995 - 2008 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:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - 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.
*
* - Neither the name of Sun Microsystems nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
*/
import java.beans.beancontext.BeanContextChildSupport;
import java.beans.beancontext.BeanContextSupport;
/**
* Test program that adds 100 beans to a context, and calls size() to report the
* number of beans currently nested. Finally, this test calls toArray() to get
* references to all child beans.
*/
public class Example2 {
public static void main(String[] args) {
// A BeanContext
BeanContextSupport context = new BeanContextSupport();
// Many JavaBeans
BeanContextChildSupport[] beans = new BeanContextChildSupport[100];
System.out.println("Number of children in the context: " + context.size());
// Create the beans and add them to the context
for (int i = 0; i < beans.length; i++) {
beans[i] = new BeanContextSupport();
context.add(beans[i]);
}
System.out.println("Number of children in the context: " + context.size());
// Context now has 100 beans in it, get references to them all
Object[] children = context.toArray();
System.out.println("Number of objects retrieved from the context: "
+ children.length);
}
}
BeanContext Support
/*
* Copyright (c) 1995 - 2008 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:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - 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.
*
* - Neither the name of Sun Microsystems nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
*/
import java.beans.beancontext.BeanContextChildSupport;
import java.beans.beancontext.BeanContextSupport;
/**
* A test program that adds a bean to a beancontext, and reports on various
* aspects of the context"s membership state. This program also shows that a
* bean"s getBeanContext() method can be called to get a reference to its
* enclosing context.
*/
public class Example1 {
private static BeanContextSupport context = new BeanContextSupport(); // The
// BeanContext
private static BeanContextChildSupport bean = new BeanContextChildSupport(); // The
// JavaBean
public static void main(String[] args) {
report();
// Add the bean to the context
System.out.println("Adding bean to context...");
context.add(bean);
report();
}
private static void report() {
// Is the context empty?
System.out.println("Is the context empty? " + context.isEmpty());
// Has the context been set for the child bean?
boolean result = (bean.getBeanContext() != null);
System.out.println("Does the bean have a context yet? " + result);
// Number of children in the context
System.out.println("Number of children in the context: " + context.size());
// Is the specific bean a member of the context?
System.out.println("Is the bean a member of the context? "
+ context.contains(bean));
// Equality test
if (bean.getBeanContext() != null) {
boolean isEqual = (bean.getBeanContext() == context); // true means both
// references point
// to the same
// object
System.out.println("Contexts are the same? " + isEqual);
}
}
}
Creates all of the objects, a tests the service capabilities
/*
* Copyright (c) 1995 - 2008 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:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - 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.
*
* - Neither the name of Sun Microsystems nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
*/
import java.beans.beancontext.BeanContextChildSupport;
import java.beans.beancontext.BeanContextServiceAvailableEvent;
import java.beans.beancontext.BeanContextServiceProvider;
import java.beans.beancontext.BeanContextServiceRevokedEvent;
import java.beans.beancontext.BeanContextServices;
import java.beans.beancontext.BeanContextServicesSupport;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.util.Iterator;
import java.util.StringTokenizer;
/**
* A test program that creates all of the objects, a tests the service
* capabilities. Run this program from the command line using java
* DocumentTester
*/
public class DocumentTester {
public static void main(String[] args) {
BeanContextServicesSupport context = new BeanContextServicesSupport(); // a
// bean
// context
DocumentBean doc1 = new DocumentBean("Test.txt");
context.add(doc1);
context.addBeanContextServicesListener(doc1); // listen for new services
WordCountServiceProvider provider = new WordCountServiceProvider();
context.addService(WordCount.class, provider); // add the service to the
// context
}
}
/*
* Copyright (c) 1995 - 2008 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:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - 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.
* - Neither the name of Sun Microsystems nor the names of its contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
*/
/**
* A JavaBean that encapsulates a text file. When added to a bean context, this
* bean listens for a WordCount service to become available. When the service
* does become available, the DocumentBean requests an instance of the service.
* The service then counts the number of words in the file, and prints a report
* to standard output.
*/
final class DocumentBean extends BeanContextChildSupport {
private File document;
private BeanContextServices context;
/**
* Creates a new DocumentBean given the name of the file to read from.
*
* @param fileName
* the name of the file to read from
*/
public DocumentBean(String fileName) {
document = new File(fileName);
}
/**
* Called when this bean detects that a new service has been registered with
* its context.
*
* @param bcsae
* the BeanContextServiceAvailableEvent
*/
public void serviceAvailable(BeanContextServiceAvailableEvent bcsae) {
System.out.println("[Detected a service being added to the context]");
// Get a reference to the context
BeanContextServices context = bcsae.getSourceAsBeanContextServices();
System.out.println("Is the context offering a WordCount service? "
+ context.hasService(WordCount.class));
// Use the service, if it"s available
if (context.hasService(WordCount.class)) {
System.out.println("Attempting to use the service...");
try {
WordCount service = (WordCount) context.getService(this, this,
WordCount.class, document, this);
System.out.println("Got the service!");
service.countWords();
} catch (Exception e) {
}
}
}
/**
* Called when this bean detects that a service has been revoked from the
* context.
*
* @param bcsre
* the BeanContextServiceRevokedEvent
*/
public void serviceRevoked(BeanContextServiceRevokedEvent bcsre) {
System.out.println("[Detected a service being revoked from the context]");
}
}
/**
* The WordCount service. Implementations of the countWords() method are
* provided by the WordCountServiceProvider class.
*/
interface WordCount {
/**
* Counts the number of words in the file.
*/
public abstract void countWords();
}
/**
* This class is the factory that delivers a word counting service. The 3
* methods defined in this class are the concrete implementations of the
* BeanContextServiceProvider interface. For this demonstration, the primary
* method of interest is getService(). The getService() methods returns a new
* WordCount instance. It is called by the bean context when a nested JavaBean
* requests the service.
*/
final class WordCountServiceProvider implements BeanContextServiceProvider {
public Object getService(BeanContextServices bcs, Object requestor,
Class serviceClass, Object serviceSelector) {
// For this demo, we know that the cast from serviceSelector
// to File will always work.
final File document = (File) serviceSelector;
/*
* Return an instance of the service. The service itself is the WordCount
* interface, which is implemented here using an anonymous inner class.
*/
return new WordCount() {
public void countWords() {
try {
// Create a Reader to the DocumentBean"s File
BufferedReader br = new BufferedReader(new FileReader(document));
String line = null;
int wordCount = 0;
while ((line = br.readLine()) != null) {
StringTokenizer st = new StringTokenizer(line);
while (st.hasMoreTokens()) {
System.out.println("Word " + (++wordCount) + " is: "
+ st.nextToken());
}
}
System.out.println("Total number of words in the document: "
+ wordCount);
System.out
.println("[WordCount service brought to you by WordCountServiceProvider]");
br.close();
} catch (Exception e) {
}
}
};
}
public void releaseService(BeanContextServices bcs, Object requestor,
Object service) {
// do nothing
}
public Iterator getCurrentServiceSelectors(BeanContextServices bcs,
Class serviceClass) {
return null; // do nothing
}
}
Demonstration of set functionality in beans
/*
* file: BeanCollections.java
* package: oreilly.hcj.collections
*
* This software is granted under the terms of the Common Public License,
* CPL, which may be found at the following URL:
* http://www-124.ibm.ru/developerworks/oss/CPLv1.0.htm
*
* Copyright(c) 2003-2005 by the authors indicated in the @author tags.
* All Rights are Reserved by the various authors.
*
########## DO NOT EDIT ABOVE THIS LINE ########## */
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.beans.PropertyVetoException;
import java.beans.VetoableChangeListener;
import java.beans.VetoableChangeSupport;
import java.io.Serializable;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/*
* file: Purchase.java package: oreilly.hcj.collections
*
* This software is granted under the terms of the Common Public License, CPL,
* which may be found at the following URL:
* http://www-124.ibm.ru/developerworks/oss/CPLv1.0.htm
*
* Copyright(c) 2003-2005 by the authors indicated in the @author tags. All
* Rights are Reserved by the various authors.
*
* ########## DO NOT EDIT ABOVE THIS LINE ##########
*/
/**
* A demo purchase bean.
*
* @author
* @version $Revision: 1.3 $
*/
public class BeanCollections {
/** A demo customer set. */
private static final Set CUSTOMERS;
static {
CUSTOMERS = new HashSet();
try {
Customer customer = null;
HashSet purchs = null;
// -- Joe
customer = new Customer();
customer.setName("Joe");
purchs = new HashSet();
purchs.add(new Purchase("Cat Food", 22.34f));
purchs.add(new Purchase("Cat Treats", 5.45f));
purchs.add(new Purchase("Cat Toy", 12.95f));
customer.setPurchases(purchs);
customer.setPurchases2(purchs);
customer.setPurchases3(purchs);
CUSTOMERS.add(customer);
// -- Jon
customer = new Customer();
customer.setName("Jon");
purchs = new HashSet();
purchs.add(new Purchase("Dog Food", 35.95f));
purchs.add(new Purchase("Dog Toy", 9.24f));
customer.setPurchases(purchs);
customer.setPurchases2(purchs);
customer.setPurchases3(purchs);
CUSTOMERS.add(customer);
// -- Jane
customer = new Customer();
customer.setName("Jane");
purchs = new HashSet();
customer.setPurchases(purchs);
customer.setPurchases2(purchs);
customer.setPurchases3(purchs);
CUSTOMERS.add(customer);
} catch (final Exception ex) {
ex.printStackTrace();
}
}
/**
* Main Method.
*
* @param args
* command line arguments.
*/
public static void main(String[] args) {
try {
Iterator iter = CUSTOMERS.iterator();
Customer customer = null;
while (iter.hasNext()) {
customer = (Customer) iter.next();
someFunction(customer);
makeCustomerReport(customer);
}
} catch (final ClassCastException ex) {
System.out.println("--- See? I told you. ---");
ex.printStackTrace(System.out);
System.out.flush();
}
System.out.println();
System.out.println("--------------------------------------");
System.out.println();
// -- Write out the two types of report to show that they
// do the same thing. Note that the order might be slightly
// different due to the nature of Set iterators.
makeGroupReport(CUSTOMERS);
System.out.println();
System.out.println("--------------------------------------");
System.out.println();
makeGroupReportBetter(CUSTOMERS);
}
/**
* Make a purchases report for a customer.
*
* @param customer
* The customer for which to make a report.
*
* @throws NullPointerException
* If customers is null.
*/
public static void makeCustomerReport(final Customer customer) {
if (customer == null) {
throw new NullPointerException();
}
Set purchases = customer.getPurchases();
if (purchases != null) {
Iterator iter = purchases.iterator();
Purchase purch = null;
System.out.println("Purchases for " + customer.getName());
while (iter.hasNext()) {
purch = (Purchase) iter.next();
System.out.println(purch.getItemName() + "\t" + purch.getPrice());
}
}
}
/**
* Prepare a report of purchases for the given customers. Example with
* potential null in Set peoperties.
*
* @param customers
* The customers for which to prepare a report.
*
* @throws NullPointerException
* If customers is null.
*/
public static void makeGroupReport(final Set customers) {
if (customers == null) {
throw new NullPointerException();
}
Iterator purchaseIter = null;
Iterator customerIter = null;
Set purchases = null;
Customer customer = null;
Purchase purch = null;
customerIter = customers.iterator();
while (customerIter.hasNext()) {
customer = (Customer) customerIter.next();
System.out.println("Purchases for " + customer.getName());
purchases = customer.getPurchases3();
if (purchases != null) {
purchaseIter = purchases.iterator();
while (purchaseIter.hasNext()) {
purch = (Purchase) purchaseIter.next();
System.out.println(purch.getItemName() + "\t" + purch.getPrice());
}
}
System.out.print("Total Purchases = ");
if (purchases != null) {
System.out.println(purchases.size());
} else {
System.out.println(0);
}
System.out.println();
}
}
/**
* Prepare a report of purchases for the given customers. Example with
* potential no nulls in Set peoperties.
*
* @param customers
* The customers for which to prepare a report.
*
* @throws NullPointerException
* If customers is null.
*/
public static void makeGroupReportBetter(final Set customers) {
if (customers == null) {
throw new NullPointerException();
}
Iterator purchaseIter = null;
Iterator customerIter = null;
Set purchases = null;
Customer customer = null;
Purchase purch = null;
customerIter = customers.iterator();
while (customerIter.hasNext()) {
customer = (Customer) customerIter.next();
System.out.println("Purchases for " + customer.getName());
purchases = customer.getPurchases3();
purchaseIter = customer.getPurchases3().iterator();
while (purchaseIter.hasNext()) {
purch = (Purchase) purchaseIter.next();
System.out.println(purch.getItemName() + "\t" + purch.getPrice());
}
System.out.println("Total Purchases = " + purchases.size());
System.out.println();
}
}
/**
* Manipulate a customer.
*
* @param customer
* The customer to manipulate.
*
* @throws NullPointerException
* If customer is null.
*/
public static void someFunction(final Customer customer) {
if (customer == null) {
throw new NullPointerException();
}
Set purchs = customer.getPurchases();
Set names = new HashSet(); // going to use to store customer names.
names.add(new String("Jason"));
purchs.add(new String("Fred")); // typo, he meant names, not purchs.
}
}
/* ########## End of File ########## */
How to create Java bean component
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.beans.PropertyChangeListener;
import java.beans.PropertyVetoException;
import java.beans.VetoableChangeListener;
import java.beans.VetoableChangeSupport;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.event.EventListenerList;
import javax.swing.event.SwingPropertyChangeSupport;
public class BakedBean extends JComponent implements Externalizable {
// Property names
public static final String BEAN_VALUE = "Value";
public static final String BEAN_COLOR = "Color";
// Properties
private Font beanFont; // simple
private Dimension beanDimension; // simple
private int beanValue; // bound
private Color beanColor; // constrained
private String text; // change
// Manages all PropertyChangeListeners
protected SwingPropertyChangeSupport propertySupporter = new SwingPropertyChangeSupport(
this);
// Manages all VetoableChangeListeners
protected VetoableChangeSupport vetoableChangeSupport = new VetoableChangeSupport(this);
protected transient ChangeEvent changeEvent = null;
protected EventListenerList listenerList = new EventListenerList();
public BakedBean() {
beanFont = new Font("SanSerif", Font.BOLD | Font.ITALIC, 12);
beanDimension = new Dimension(150, 100);
beanValue = 0;
beanColor = Color.black;
text = "BakedBean #";
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(beanColor);
g.setFont(beanFont);
g.drawString(text + beanValue, 30, 30);
}
public void setBeanFont(Font font) {
beanFont = font;
}
public Font getBeanFont() {
return beanFont;
}
public void setBeanValue(int newValue) {
int oldValue = beanValue;
beanValue = newValue;
// Notify all PropertyChangeListeners
propertySupporter.firePropertyChange(BEAN_VALUE, new Integer(oldValue),
new Integer(newValue));
}
public int getBeanValue() {
return beanValue;
}
public void setBeanColor(Color newColor) throws PropertyVetoException {
Color oldColor = beanColor;
vetoableChangeSupport.fireVetoableChange(BEAN_COLOR, oldColor, newColor);
beanColor = newColor;
propertySupporter.firePropertyChange(BEAN_COLOR, oldColor, newColor);
}
public Color getBeanColor() {
return beanColor;
}
public void setBeanString(String newString) {
text = newString;
// Notify all ChangeListeners
fireStateChanged();
}
public String getBeanString() {
return text;
}
public void setPreferredSize(Dimension dim) {
beanDimension = dim;
}
public Dimension getPreferredSize() {
return beanDimension;
}
public void setMinimumSize(Dimension dim) {
beanDimension = dim;
}
public Dimension getMinimumSize() {
return beanDimension;
}
public void addPropertyChangeListener(PropertyChangeListener l) {
propertySupporter.addPropertyChangeListener(l);
}
public void removePropertyChangeListener(PropertyChangeListener l) {
propertySupporter.removePropertyChangeListener(l);
}
public void addVetoableChangeListener(VetoableChangeListener l) {
vetoableChangeSupport.addVetoableChangeListener(l);
}
public void removeVetoableChangeListener(VetoableChangeListener l) {
vetoableChangeSupport.removeVetoableChangeListener(l);
}
// Remember that EventListenerList is an array of
// key/value pairs.
// key = XXListener class reference
// value = XXListener instance
public void addChangeListener(ChangeListener l) {
listenerList.add(ChangeListener.class, l);
}
public void removeChangeListener(ChangeListener l) {
listenerList.remove(ChangeListener.class, l);
}
// EventListenerList dispatching code.
protected void fireStateChanged() {
Object[] listeners = listenerList.getListenerList();
// Process the listeners last to first, notifying
// those that are interested in this event
for (int i = listeners.length - 2; i >= 0; i -= 2) {
if (listeners[i] == ChangeListener.class) {
if (changeEvent == null)
changeEvent = new ChangeEvent(this);
((ChangeListener) listeners[i + 1]).stateChanged(changeEvent);
}
}
}
public void writeExternal(ObjectOutput out) throws IOException {
out.writeObject(beanFont);
out.writeObject(beanDimension);
out.writeInt(beanValue);
out.writeObject(beanColor);
out.writeObject(text);
}
public void readExternal(ObjectInput in) throws IOException,
ClassNotFoundException {
setBeanFont((Font) in.readObject());
setPreferredSize((Dimension) in.readObject());
// Use preferred size for minimum size..
setMinimumSize(getPreferredSize());
setBeanValue(in.readInt());
try {
setBeanColor((Color) in.readObject());
} catch (PropertyVetoException pve) {
System.out.println("Color change vetoed..");
}
setBeanString((String) in.readObject());
}
public static void main(String[] args) {
JFrame frame = new JFrame("BakedBean");
frame.getContentPane().add(new BakedBean());
frame.setVisible(true);
frame.pack();
}
}
how to use the instantiateChild() convenience method to create a bean automatically nested into a bean context
/*
* Copyright (c) 1995 - 2008 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:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - 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.
*
* - Neither the name of Sun Microsystems nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
*/
import java.beans.beancontext.BeanContextChildSupport;
import java.beans.beancontext.BeanContextSupport;
import java.io.IOException;
/**
* An example of how to use the instantiateChild() convenience method to create
* a bean automatically nested into a bean context.
*/
public class Example3 {
public static void main(String[] args) {
BeanContextSupport context = new BeanContextSupport();
System.out.println("Number of children nested into the context: "
+ context.size());
BeanContextChildSupport child = null;
try {
child = (BeanContextChildSupport) context
.instantiateChild("java.beans.beancontext.BeanContextChildSupport");
} catch (IOException e) {
System.out.println("IOException occurred: " + e.getMessage());
} catch (ClassNotFoundException e) {
System.out.println("Class not found: " + e.getMessage());
}
System.out.println("Number of children nested into the context: "
+ context.size());
}
}
illustrate delivery of the BeanContextMembershipEvent
/*
* Copyright (c) 1995 - 2008 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:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - 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.
*
* - Neither the name of Sun Microsystems nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
*/
import java.beans.beancontext.BeanContextChildSupport;
import java.beans.beancontext.BeanContextMembershipEvent;
import java.beans.beancontext.BeanContextMembershipListener;
import java.beans.beancontext.BeanContextSupport;
/**
* A simple test program to illustrate delivery of the
* BeanContextMembershipEvent.
*/
public class MembershipTest {
public static void main(String[] args) {
BeanContextSupport context = new BeanContextSupport(); // the context
MyMembershipListener listener = new MyMembershipListener();
BeanContextChildSupport bean = new BeanContextChildSupport(); // a JavaBean
context.addBeanContextMembershipListener(listener); // now listening!
context.add(bean);
context.remove(bean);
}
}
/**
* A custom implementation of the BeanContextMembershipListener interface.
*/
class MyMembershipListener implements BeanContextMembershipListener {
public void childrenAdded(BeanContextMembershipEvent bcme) {
System.out.println("Another bean has been added to the context.");
}
public void childrenRemoved(BeanContextMembershipEvent bcme) {
System.out.println("A bean has been removed from the context.");
}
}
Simple Java bean container
import java.awt.Color;
import java.awt.ruponent;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.beans.PropertyChangeListener;
import java.beans.PropertyVetoException;
import java.beans.VetoableChangeListener;
import java.beans.VetoableChangeSupport;
import java.io.Externalizable;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
import javax.swing.BoxLayout;
import javax.swing.ButtonGroup;
import javax.swing.JComponent;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JPopupMenu;
import javax.swing.JRadioButtonMenuItem;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.event.EventListenerList;
import javax.swing.event.SwingPropertyChangeSupport;
public class BeanContainer extends JFrame implements FocusListener {
protected File currentDir = new File(".");
protected Component currentBean;
protected String className = "MyBean";
protected JFileChooser fileChooser = new JFileChooser();
public BeanContainer() {
super("Simple Bean Container");
getContentPane().setLayout(new FlowLayout());
setSize(300, 300);
JPopupMenu.setDefaultLightWeightPopupEnabled(false);
JMenuBar menuBar = createMenuBar();
setJMenuBar(menuBar);
WindowListener wndCloser = new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
};
addWindowListener(wndCloser);
setVisible(true);
}
protected JMenuBar createMenuBar() {
JMenuBar menuBar = new JMenuBar();
JMenu mFile = new JMenu("File");
JMenuItem mItem = new JMenuItem("New...");
ActionListener lst = new ActionListener() {
public void actionPerformed(ActionEvent e) {
NewBeanThread t = new NewBeanThread();
t.start();
}
};
mItem.addActionListener(lst);
mFile.add(mItem);
mItem = new JMenuItem("Load...");
lst = new ActionListener() {
public void actionPerformed(ActionEvent e) {
LoadBeanThread t = new LoadBeanThread();
t.start();
}
};
mItem.addActionListener(lst);
mFile.add(mItem);
mItem = new JMenuItem("Save...");
lst = new ActionListener() {
public void actionPerformed(ActionEvent e) {
SaveBeanThread t = new SaveBeanThread();
t.start();
}
};
mItem.addActionListener(lst);
mFile.add(mItem);
mFile.addSeparator();
mItem = new JMenuItem("Exit");
lst = new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
};
mItem.addActionListener(lst);
mFile.add(mItem);
menuBar.add(mFile);
JMenu mEdit = new JMenu("Edit");
mItem = new JMenuItem("Delete");
lst = new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (currentBean == null)
return;
getContentPane().remove(currentBean);
currentBean = null;
validate();
repaint();
}
};
mItem.addActionListener(lst);
mEdit.add(mItem);
menuBar.add(mEdit);
JMenu mLayout = new JMenu("Layout");
ButtonGroup group = new ButtonGroup();
mItem = new JRadioButtonMenuItem("FlowLayout");
mItem.setSelected(true);
lst = new ActionListener() {
public void actionPerformed(ActionEvent e) {
getContentPane().setLayout(new FlowLayout());
validate();
repaint();
}
};
mItem.addActionListener(lst);
group.add(mItem);
mLayout.add(mItem);
mItem = new JRadioButtonMenuItem("GridLayout");
lst = new ActionListener() {
public void actionPerformed(ActionEvent e) {
int col = 3;
int row = (int) Math.ceil(getContentPane().getComponentCount()
/ (double) col);
getContentPane().setLayout(new GridLayout(row, col, 10, 10));
validate();
repaint();
}
};
mItem.addActionListener(lst);
group.add(mItem);
mLayout.add(mItem);
mItem = new JRadioButtonMenuItem("BoxLayout - X");
lst = new ActionListener() {
public void actionPerformed(ActionEvent e) {
getContentPane().setLayout(
new BoxLayout(getContentPane(), BoxLayout.X_AXIS));
validate();
repaint();
}
};
mItem.addActionListener(lst);
group.add(mItem);
mLayout.add(mItem);
mItem = new JRadioButtonMenuItem("BoxLayout - Y");
lst = new ActionListener() {
public void actionPerformed(ActionEvent e) {
getContentPane().setLayout(
new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));
validate();
repaint();
}
};
mItem.addActionListener(lst);
group.add(mItem);
mLayout.add(mItem);
group.add(mItem);
mLayout.add(mItem);
menuBar.add(mLayout);
return menuBar;
}
public void focusGained(FocusEvent e) {
currentBean = e.getComponent();
repaint();
}
public void focusLost(FocusEvent e) {
}
// This is a heavyweight component so we override paint
// instead of paintComponent. super.paint(g) will
// paint all child components first, and then we
// simply draw over top of them.
public void paint(Graphics g) {
super.paint(g);
if (currentBean == null)
return;
Point pt = getLocationOnScreen();
Point pt1 = currentBean.getLocationOnScreen();
int x = pt1.x - pt.x - 2;
int y = pt1.y - pt.y - 2;
int w = currentBean.getWidth() + 2;
int h = currentBean.getHeight() + 2;
g.setColor(Color.black);
g.drawRect(x, y, w, h);
}
public static void main(String argv[]) {
new BeanContainer();
}
class SaveBeanThread extends Thread {
public void run() {
if (currentBean == null)
return;
fileChooser
.setDialogTitle("Please choose file to serialize bean");
fileChooser.setCurrentDirectory(currentDir);
int result = fileChooser
.showSaveDialog(BeanContainer.this);
repaint();
if (result != JFileChooser.APPROVE_OPTION)
return;
currentDir = fileChooser.getCurrentDirectory();
File fChoosen = fileChooser.getSelectedFile();
try {
FileOutputStream fStream = new FileOutputStream(
fChoosen);
ObjectOutput stream = new ObjectOutputStream(
fStream);
stream.writeObject(currentBean);
stream.close();
fStream.close();
} catch (Exception ex) {
ex.printStackTrace();
JOptionPane.showMessageDialog(BeanContainer.this,
"Error: " + ex.toString(), "Warning",
JOptionPane.WARNING_MESSAGE);
}
}
}
class LoadBeanThread extends Thread{
public void run() {
fileChooser.setCurrentDirectory(currentDir);
fileChooser
.setDialogTitle("Please select file with serialized bean");
int result = fileChooser
.showOpenDialog(BeanContainer.this);
repaint();
if (result != JFileChooser.APPROVE_OPTION)
return;
currentDir = fileChooser.getCurrentDirectory();
File fChoosen = fileChooser.getSelectedFile();
try {
FileInputStream fStream = new FileInputStream(
fChoosen);
ObjectInput stream = new ObjectInputStream(fStream);
Object obj = stream.readObject();
if (obj instanceof Component) {
currentBean = (Component) obj;
currentBean
.addFocusListener(BeanContainer.this);
currentBean.requestFocus();
getContentPane().add(currentBean);
}
stream.close();
fStream.close();
validate();
} catch (Exception ex) {
ex.printStackTrace();
JOptionPane.showMessageDialog(BeanContainer.this,
"Error: " + ex.toString(), "Warning",
JOptionPane.WARNING_MESSAGE);
}
repaint();
}
}
class NewBeanThread extends Thread {
public void run() {
String result = (String) JOptionPane.showInputDialog(
BeanContainer.this,
"Use the following name for demanstration",
"Input", JOptionPane.INFORMATION_MESSAGE, null,
null, className);
repaint();
if (result == null)
return;
try {
className = result;
Class cls = Class.forName(result);
Object obj = cls.newInstance();
if (obj instanceof Component) {
currentBean = (Component) obj;
currentBean
.addFocusListener(BeanContainer.this);
currentBean.requestFocus();
getContentPane().add(currentBean);
}
validate();
} catch (Exception ex) {
ex.printStackTrace();
JOptionPane.showMessageDialog(BeanContainer.this,
"Error: " + ex.toString(), "Warning",
JOptionPane.WARNING_MESSAGE);
}
}
}
}
class MyBean extends JComponent implements Externalizable {
// Property names
public static final String BEAN_VALUE = "Value";
public static final String BEAN_COLOR = "Color";
// Properties
private Font beanFont; // simple
private Dimension beanDimension; // simple
private int beanValue; // bound
private Color beanColor; // constrained
private String text; // change
// Manages all PropertyChangeListeners
protected SwingPropertyChangeSupport propertySupporter = new SwingPropertyChangeSupport(
this);
// Manages all VetoableChangeListeners
protected VetoableChangeSupport vetoableChangeSupport = new VetoableChangeSupport(this);
protected transient ChangeEvent changeEvent = null;
protected EventListenerList listenerList = new EventListenerList();
public MyBean() {
beanFont = new Font("SanSerif", Font.BOLD | Font.ITALIC, 12);
beanDimension = new Dimension(150, 100);
beanValue = 0;
beanColor = Color.black;
text = "BakedBean #";
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(beanColor);
g.setFont(beanFont);
g.drawString(text + beanValue, 30, 30);
}
public void setBeanFont(Font font) {
beanFont = font;
}
public Font getBeanFont() {
return beanFont;
}
public void setBeanValue(int newValue) {
int oldValue = beanValue;
beanValue = newValue;
// Notify all PropertyChangeListeners
propertySupporter.firePropertyChange(BEAN_VALUE, new Integer(oldValue),
new Integer(newValue));
}
public int getBeanValue() {
return beanValue;
}
public void setBeanColor(Color newColor) throws PropertyVetoException {
Color oldColor = beanColor;
vetoableChangeSupport.fireVetoableChange(BEAN_COLOR, oldColor, newColor);
beanColor = newColor;
propertySupporter.firePropertyChange(BEAN_COLOR, oldColor, newColor);
}
public Color getBeanColor() {
return beanColor;
}
public void setBeanString(String newString) {
text = newString;
// Notify all ChangeListeners
fireStateChanged();
}
public String getBeanString() {
return text;
}
public void setPreferredSize(Dimension dim) {
beanDimension = dim;
}
public Dimension getPreferredSize() {
return beanDimension;
}
public void setMinimumSize(Dimension dim) {
beanDimension = dim;
}
public Dimension getMinimumSize() {
return beanDimension;
}
public void addPropertyChangeListener(PropertyChangeListener l) {
propertySupporter.addPropertyChangeListener(l);
}
public void removePropertyChangeListener(PropertyChangeListener l) {
propertySupporter.removePropertyChangeListener(l);
}
public void addVetoableChangeListener(VetoableChangeListener l) {
vetoableChangeSupport.addVetoableChangeListener(l);
}
public void removeVetoableChangeListener(VetoableChangeListener l) {
vetoableChangeSupport.removeVetoableChangeListener(l);
}
// Remember that EventListenerList is an array of
// key/value pairs.
// key = XXListener class reference
// value = XXListener instance
public void addChangeListener(ChangeListener l) {
listenerList.add(ChangeListener.class, l);
}
public void removeChangeListener(ChangeListener l) {
listenerList.remove(ChangeListener.class, l);
}
// EventListenerList dispatching code.
protected void fireStateChanged() {
Object[] listeners = listenerList.getListenerList();
// Process the listeners last to first, notifying
// those that are interested in this event
for (int i = listeners.length - 2; i >= 0; i -= 2) {
if (listeners[i] == ChangeListener.class) {
if (changeEvent == null)
changeEvent = new ChangeEvent(this);
((ChangeListener) listeners[i + 1]).stateChanged(changeEvent);
}
}
}
public void writeExternal(ObjectOutput out) throws IOException {
out.writeObject(beanFont);
out.writeObject(beanDimension);
out.writeInt(beanValue);
out.writeObject(beanColor);
out.writeObject(text);
}
public void readExternal(ObjectInput in) throws IOException,
ClassNotFoundException {
setBeanFont((Font) in.readObject());
setPreferredSize((Dimension) in.readObject());
// Use preferred size for minimum size..
setMinimumSize(getPreferredSize());
setBeanValue(in.readInt());
try {
setBeanColor((Color) in.readObject());
} catch (PropertyVetoException pve) {
System.out.println("Color change vetoed..");
}
setBeanString((String) in.readObject());
}
public static void main(String[] args) {
JFrame frame = new JFrame("BakedBean");
frame.getContentPane().add(new MyBean());
frame.setVisible(true);
frame.pack();
}
}
Use assert the verify value
/*
* Copyright (c) 1995 - 2008 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:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - 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.
*
* - Neither the name of Sun Microsystems nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
*/
public class Card {
private final int rank;
private final int suit;
// Kinds of suits
public final static int DIAMONDS = 1;
public final static int CLUBS = 2;
public final static int HEARTS = 3;
public final static int SPADES = 4;
// Kinds of ranks
public final static int ACE = 1;
public final static int DEUCE = 2;
public final static int THREE = 3;
public final static int FOUR = 4;
public final static int FIVE = 5;
public final static int SIX = 6;
public final static int SEVEN = 7;
public final static int EIGHT = 8;
public final static int NINE = 9;
public final static int TEN = 10;
public final static int JACK = 11;
public final static int QUEEN = 12;
public final static int KING = 13;
public Card(int rank, int suit) {
assert isValidRank(rank);
assert isValidSuit(suit);
this.rank = rank;
this.suit = suit;
}
public int getSuit() {
return suit;
}
public int getRank() {
return rank;
}
public static boolean isValidRank(int rank) {
return ACE <= rank && rank <= KING;
}
public static boolean isValidSuit(int suit) {
return DIAMONDS <= suit && suit <= SPADES;
}
public static String rankToString(int rank) {
switch (rank) {
case ACE:
return "Ace";
case DEUCE:
return "Deuce";
case THREE:
return "Three";
case FOUR:
return "Four";
case FIVE:
return "Five";
case SIX:
return "Six";
case SEVEN:
return "Seven";
case EIGHT:
return "Eight";
case NINE:
return "Nine";
case TEN:
return "Ten";
case JACK:
return "Jack";
case QUEEN:
return "Queen";
case KING:
return "King";
default:
// Handle an illegal argument. There are generally two
// ways to handle invalid arguments, throwing an exception
// (see the section on Handling Exceptions) or return null
return null;
}
}
public static String suitToString(int suit) {
switch (suit) {
case DIAMONDS:
return "Diamonds";
case CLUBS:
return "Clubs";
case HEARTS:
return "Hearts";
case SPADES:
return "Spades";
default:
return null;
}
}
public static void main(String[] args) {
// must run program with -ea flag (java -ea ..) to
// use assert statements
assert rankToString(ACE) == "Ace";
assert rankToString(DEUCE) == "Deuce";
assert rankToString(THREE) == "Three";
assert rankToString(FOUR) == "Four";
assert rankToString(FIVE) == "Five";
assert rankToString(SIX) == "Six";
assert rankToString(SEVEN) == "Seven";
assert rankToString(EIGHT) == "Eight";
assert rankToString(NINE) == "Nine";
assert rankToString(TEN) == "Ten";
assert rankToString(JACK) == "Jack";
assert rankToString(QUEEN) == "Queen";
assert rankToString(KING) == "King";
assert suitToString(DIAMONDS) == "Diamonds";
assert suitToString(CLUBS) == "Clubs";
assert suitToString(HEARTS) == "Hearts";
assert suitToString(SPADES) == "Spades";
}
}
