s10.htm

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              f.setBounds(x,y,w,h);<br>
              f.setVisible(true);</p>
            <p> statusArea.setBorder(BorderFactory.createEtchedBorder());<br>
              statusArea.setLayout(new FlowLayout(FlowLayout.LEFT,0,0));<br>
              statusArea.add(status);<br>
              status.setHorizontalAlignment(JLabel.LEFT);</p>
            <p> f.setDefaultCloseOperation(<br>
              WindowConstants.DISPOSE_ON_CLOSE);</p>
            <p> f.addWindowListener(new WindowAdapter() {<br>
              public void windowClosed(WindowEvent e) {<br>
              System.exit(0);<br>
              }<br>
              });<br>
              }<br>
              static public JPanel getStatusArea() {<br>
              return statusArea;<br>
              }<br>
              static public void updateStatus(String s) {<br>
              status.setText(s);<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 10.3.2 JMenuItem属性</p>
            <p>&nbsp;</p>
            <p> 10.3.3 JMenuItem事件</p>
            <p>&nbsp;</p>
            <p align="center"><b>例10-5 监听菜单项动作和菜单项变化事件</b></p>
            <hr noshade size="1">
            import javax.swing.*;<br>
            import javax.swing.event.*;<br>
            import java.awt.*;<br>
            import java.awt.event.*;
            <p>public class Test extends JApplet {<br>
              public void init() {<br>
              JMenuBar mb = new JMenuBar();<br>
              JMenu fileMenu = new JMenu(&quot;File&quot;);<br>
              JMenuItem newItem = new JMenuItem(&quot;New ...&quot;),<br>
              openItem = new JMenuItem(&quot;Open ...&quot;),<br>
              saveItem = new JMenuItem(&quot;Save&quot;),<br>
              saveAsItem = new JMenuItem(&quot;Save As ...&quot;),<br>
              exitItem = new JMenuItem(&quot;Exit&quot;);<br>
              Listener listener = new Listener(this);</p>
            <p> fileMenu.add(newItem);<br>
              fileMenu.add(openItem);<br>
              fileMenu.add(saveItem);<br>
              fileMenu.add(saveAsItem);<br>
              fileMenu.addSeparator();<br>
              fileMenu.add(exitItem);</p>
            <p> newItem.setActionCommand(&quot;Create a New Document&quot;);<br>
              openItem.setActionCommand(&quot;Open an Existing Document&quot;);<br>
              saveItem.setActionCommand(&quot;Save Document&quot;);<br>
              saveAsItem.setActionCommand(&quot;Save Document As ...&quot;);<br>
              exitItem.setActionCommand(&quot;Exit the applet&quot;);</p>
            <p> newItem.addChangeListener(listener);<br>
              openItem.addChangeListener(listener);<br>
              saveItem.addChangeListener(listener);<br>
              saveAsItem.addChangeListener(listener);<br>
              exitItem.addChangeListener(listener);</p>
            <p> mb.add(fileMenu);<br>
              setJMenuBar(mb);</p>
            <p> exitItem.addActionListener(new ActionListener() {<br>
              public void actionPerformed(ActionEvent e) {<br>
              System.exit(0);<br>
              }<br>
              });<br>
              }<br>
              }<br>
              class Listener implements ChangeListener {<br>
              private JApplet applet;</p>
            <p> public Listener(JApplet applet) {<br>
              this.applet = applet;<br>
              }<br>
              public void stateChanged(ChangeEvent e) {<br>
              JMenuItem b = (JMenuItem)e.getSource();</p>
            <p> if(b.isArmed())<br>
              applet.showStatus(b.getActionCommand());<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 10.3.4 JMenuItem类总结</p>
            <p>&nbsp;</p>
            <p> 10.3.5 AWT兼容</p>
            <p>&nbsp;</p>
            <p> 10.4 JCheckBoxMenuItem</p>
            <p>&nbsp;</p>
            <p align="center"><b>例10-6 实例化复选框菜单项</b></p>
            <hr noshade size="1">
            import javax.swing.*;<br>
            import java.awt.*;<br>
            import java.awt.event.*;
            <p>public class Test extends JApplet {<br>
              public void init() {<br>
              Container contentPane = getContentPane();</p>
            <p> JMenuBar mb = new JMenuBar();<br>
              JMenu checkBoxMenu = new JMenu(&quot;Endangered Species&quot;);</p>
            <p> ImageIcon crabIcon = new ImageIcon(&quot;crab.gif&quot;);<br>
              ImageIcon eagleIcon = new ImageIcon(&quot;eagle.gif&quot;);</p>
            <p> JMenuItem <br>
              crabItem = new JCheckBoxMenuItem(crabIcon),<br>
              eagleItem = new JCheckBoxMenuItem(&quot;eagle&quot;, <br>
              eagleIcon, true),<br>
              ladybugItem = new JCheckBoxMenuItem(&quot;ladybug&quot;);</p>
            <p> checkBoxMenu.add(crabItem);<br>
              checkBoxMenu.add(eagleItem);<br>
              checkBoxMenu.add(ladybugItem);</p>
            <p> ladybugItem.setMnemonic('l');</p>
            <p> mb.add(checkBoxMenu);<br>
              setJMenuBar(mb);<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 10.4.1 JCheckBoxMenuItem属性</p>
            <p>&nbsp;</p>
            <p> 10.4.2 JCheckBoxMenuItem事件</p>
            <p>&nbsp;</p>
            <p align="center"><b>例10-7 访问JCheckBoxMenuItem状态</b></p>
            <hr noshade size="1">
            import javax.swing.*;<br>
            import javax.swing.event.*;<br>
            import java.awt.*;<br>
            import java.awt.event.*;
            <p>public class Test extends JApplet {<br>
              private ImageIcon crabIcon = new ImageIcon(&quot;crab.gif&quot;);<br>
              private ImageIcon eagleIcon = new ImageIcon(&quot;eagle.gif&quot;);</p>
            <p> private JCheckBoxMenuItem <br>
              crabItem = new JCheckBoxMenuItem(crabIcon),<br>
              eagleItem = new JCheckBoxMenuItem(&quot;eagle&quot;, eagleIcon),<br>
              ladybugItem = new JCheckBoxMenuItem(&quot;ladybug&quot;);</p>
            <p> public void init() {<br>
              Container contentPane = getContentPane();</p>
            <p> JMenuBar mb = new JMenuBar();<br>
              JMenu checkBoxMenu = new JMenu(&quot;Endangered Species&quot;);<br>
              Listener listener = new Listener();</p>
            <p> checkBoxMenu.add(crabItem);<br>
              checkBoxMenu.add(eagleItem);<br>
              checkBoxMenu.add(ladybugItem);</p>
            <p> crabItem.addActionListener(listener);<br>
              eagleItem.addActionListener(listener);<br>
              ladybugItem.addActionListener(listener);</p>
            <p> mb.add(checkBoxMenu);<br>
              setJMenuBar(mb);<br>
              }<br>
              class Listener implements ActionListener {<br>
              public void actionPerformed(ActionEvent e) {<br>
              showStatus(&quot;crab: &quot; + crabItem.getState() + &quot;, &quot; 
              +<br>
              &quot;eagle: &quot; + eagleItem.getState() + &quot;, &quot; +<br>
              &quot;ladybug: &quot; + ladybugItem.getState());<br>
              }<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 10.4.3 JCheckBoxMenuItem类总结</p>
            <p>&nbsp;</p>
            <p> 10.4.4 AWT兼容</p>
            <p>&nbsp;</p>
            <p> 10.5 JRadioButtonMenuItem</p>
            <p>&nbsp;</p>
            <p align="center"><b>例10-8 实例化单选按钮菜单项</b></p>
            <hr noshade size="1">
            import javax.swing.*;<br>
            import javax.swing.event.*;<br>
            import java.awt.*;<br>
            import java.awt.event.*;
            <p>public class Test extends JApplet {<br>
              public void init() {<br>
              Container contentPane = getContentPane();</p>
            <p> JMenuBar mb = new JMenuBar();<br>
              JMenu radioMenu = new JMenu(&quot;Favorite Animal&quot;);</p>
            <p> ImageIcon crabIcon = new ImageIcon(&quot;crab.gif&quot;);<br>
              ImageIcon eagleIcon = new ImageIcon(&quot;eagle.gif&quot;);</p>
            <p> final JMenuItem <br>
              crabItem = new JRadioButtonMenuItem(crabIcon),<br>
              eagleItem = new JRadioButtonMenuItem(&quot;eagle&quot;, <br>
              eagleIcon),<br>
              ladybugItem = new JRadioButtonMenuItem(&quot;ladybug&quot;);</p>
            <p> radioMenu.add(crabItem);<br>
              radioMenu.add(eagleItem);<br>
              radioMenu.add(ladybugItem);</p>
            <p> mb.add(radioMenu);<br>
              setJMenuBar(mb);<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 10.5.1 JRadioButtonMenuItem属性</p>
            <p>&nbsp;</p>
            <p> 10.5.2 JRadioButtonMenuItem事件</p>
            <p>&nbsp;</p>
            <p align="center"><b>例10-9 为JRadioButton的实例监视事件</b></p>
            <hr noshade size="1">
            import javax.swing.*;<br>
            import javax.swing.event.*;<br>
            import java.awt.*;<br>
            import java.awt.event.*;
            <p>public class Test extends JApplet {<br>
              private ImageIcon crabIcon = new ImageIcon(&quot;crab.gif&quot;, 
              <br>
              &quot;Crab&quot;);<br>
              private ImageIcon eagleIcon = new ImageIcon(&quot;eagle.gif&quot;, 
              <br>
              &quot;Eagle&quot;);<br>
              private JMenuItem <br>
              crabItem = new JRadioButtonMenuItem(crabIcon),<br>
              eagleItem = new JRadioButtonMenuItem(&quot;eagle&quot;, <br>
              eagleIcon),<br>
              ladybugItem = new JRadioButtonMenuItem(&quot;ladybug&quot;);</p>
            <p> public void init() {<br>
              Container contentPane = getContentPane();</p>
            <p> JMenuBar mb = new JMenuBar();<br>
              JMenu radioMenu = new JMenu(&quot;Favorite Animal&quot;);</p>
            <p> AnItemListener itemListener = new AnItemListener();<br>
              AnActionListener actionListener = new AnActionListener();<br>
              AChangeListener changeListener = new AChangeListener();</p>
            <p> radioMenu.add(crabItem);<br>
              radioMenu.add(eagleItem);<br>
              radioMenu.add(ladybugItem);</p>
            <p> ButtonGroup group = new ButtonGroup();<br>
              group.add(crabItem);<br>
              group.add(eagleItem);<br>
              group.add(ladybugItem);</p>
            <p> mb.add(radioMenu);<br>
              setJMenuBar(mb);</p>
            <p> crabItem.addItemListener(itemListener);<br>
              eagleItem.addItemListener(itemListener);<br>
              ladybugItem.addItemListener(itemListener);</p>
            <p> crabItem.addActionListener(actionListener);<br>
              eagleItem.addActionListener(actionListener);<br>
              ladybugItem.addActionListener(actionListener);</p>
            <p> crabItem.addChangeListener(changeListener);<br>
              eagleItem.addChangeListener(changeListener);<br>
              ladybugItem.addChangeListener(changeListener);<br>
              }<br>
              private String getItemDescription(JMenuItem item) {<br>
              String s;<br>
              ImageIcon icon = (ImageIcon)item.getIcon();</p>
            <p> if(icon != null) return icon.getDescription();<br>
              else return item.getText();<br>
              }</p>
            <p> // Inner class event handlers follow ...</p>
            <p> class AnActionListener implements ActionListener {<br>
              public void actionPerformed(ActionEvent e) {<br>
              JMenuItem item = (JMenuItem) e.getSource();<br>
              String s = getItemDescription(item);<br>
              showStatus(s + &quot; activated&quot;);</p>
            <p> System.out.println(&quot;action event fired&quot;);<br>
              }<br>
              };<br>
              class AChangeListener implements ChangeListener { <br>
              public void stateChanged(ChangeEvent e) {<br>
              Object[] selectedObjs = <br>
              ladybugItem.getSelectedObjects();</p>
            <p> if(selectedObjs == null)<br>
              System.out.println(&quot;selected objs is null&quot;);<br>
              else<br>
              System.out.println(selectedObjs[0] + &quot;selected&quot;);</p>
            <p> JMenuItem item = (JMenuItem)e.getSource();</p>
            <p> if(item.isArmed()) {<br>
              String s = getItemDescription(item);<br>
              showStatus(s + &quot; armed&quot;);<br>
              }<br>
              System.out.println(&quot;change event fired&quot;);<br>
              }<br>
              };<br>
              class AnItemListener implements ItemListener { <br>
              public void itemStateChanged(ItemEvent e) {<br>
              JMenuItem item = (JMenuItem) e.getSource();<br>
              String s = getItemDescription(item);</p>
            <p> if(e.getStateChange() == ItemEvent.SELECTED)<br>
              s += &quot; selected&quot;;<br>
              else<br>
              s += &quot; deselected&quot;;</p>
            <p> showStatus(s);<br>
              System.out.println(&quot;item event fired&quot;);<br>