threepanels.java

程序练习中包括书中实例程序代码和练习中要用到的代码,是压缩文件

package examples.awt;
import java.awt.*;
import java.awt.event.*;
/** An example class used to demonstrate the basics of 
  * creating components such as panels, arranging
  * components using layout objects, and nesting
  * components inside each other.
  */
public class ThreePanels extends Frame {
   private Panel upper, middle, lower;
   private TextField text;
   private Button black, red, green;
   private Checkbox disable;
   /** Class constructor method
     * @param titleText Window's title bar text
     */
   public ThreePanels( String titleText ) {
      super( titleText );
      setLayout( new BorderLayout() );
      addWindowListener( new WindowAdapter() {
            /** End the program when the user
              * closes the window
              */
            public void
            windowClosing( WindowEvent e ) {
               ThreePanels.this.dispose();
               System.exit( 0 );
            }

         }
      );
      upper = new Panel();
      upper.setLayout( new BorderLayout() );
      text = new TextField( 
         "Change the color of this text" );
      upper.add( text, BorderLayout.CENTER );
      middle = new Panel();
      middle.setLayout( new FlowLayout( 
         FlowLayout.CENTER ) );
      black = new Button( "Black" );
      black.addActionListener(
         new ButtonListener( Color.black ) );
      middle.add( black );
      red = new Button( "Red" );
      red.addActionListener(
         new ButtonListener( Color.red ) );
      middle.add( red );
      green = new Button( "Green" );
      green.addActionListener(
         new ButtonListener( Color.green ) );
      middle.add( green );

      lower = new Panel();
      lower.setLayout( new FlowLayout( 
         FlowLayout.RIGHT ) );
      disable = new Checkbox( "Disable changes" );
      disable.addItemListener( new ItemListener() {
            /** Disable and enable the buttons
              */
            public void
            itemStateChanged( ItemEvent e ) {
               boolean enabled
                  = ( e.getStateChange()
                      == ItemEvent.DESELECTED );
               black.setEnabled( enabled );
               red.setEnabled( enabled );
               green.setEnabled( enabled );
            }
         }
      );
      lower.add( disable );
      add( upper, BorderLayout.NORTH );
      add( middle, BorderLayout.CENTER );
      add( lower, BorderLayout.SOUTH );
      pack();
      setVisible( true );
   }
   class ButtonListener implements ActionListener {
      private Color c;
      /** Class constructor
        * @param c the color for this button
        */
      public ButtonListener( Color c ) {
         this.c = c;
      }
      /** Respond to the action events
        * @param e The click event
        */
      public void actionPerformed( ActionEvent e ) {
         text.setForeground( c );
      }
   }
   /** The test method for the class
     * @param args not used
     */
   public static void main( String[] args ) {
      new ThreePanels( "Three Panels Sample" );
   }
}