keydemo.java

来自「Java语言」· Java 代码 · 共 80 行

// Demonstrating keystroke events.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class KeyDemo extends JFrame implements KeyListener {
   private String line1 = "", line2 = "";
   private String line3 = "";
   private JTextArea textArea;

   public KeyDemo()
   {
      super( "Demonstrating Keystroke Events" );

      textArea = new JTextArea( 10, 15 );
      textArea.setText( "Press any key on the keyboard..." );
      textArea.setEnabled( false );

      // allow frame to process Key events
      addKeyListener( this );

      getContentPane().add( textArea );  

      setSize( 350, 100 );
      show();
   }

   public void keyPressed( KeyEvent e )
   {
      line1 = "Key pressed: " +
               e.getKeyText( e.getKeyCode() );
      setLines2and3( e );
   }

   public void keyReleased( KeyEvent e )
   {
      line1 = "Key released: " +
               e.getKeyText( e.getKeyCode() );
      setLines2and3( e );
   }

   public void keyTyped( KeyEvent e )
   {
      line1 = "Key typed: " + e.getKeyChar();
      setLines2and3( e );
   }

   private void setLines2and3( KeyEvent e )
   {
      line2 = "This key is " +
              ( e.isActionKey() ? "" : "not " ) +
              "an action key";

      String temp = 
         e.getKeyModifiersText( e.getModifiers() );

      line3 = "Modifier keys pressed: " +
              ( temp.equals( "" ) ? "none" : temp );

      textArea.setText(
         line1 + "\n" + line2 + "\n" + line3 + "\n" );
   }

   public static void main( String args[] )
   {
      KeyDemo app = new KeyDemo();

      app.addWindowListener(
         new WindowAdapter() {
            public void windowClosing( WindowEvent e )
            {
               System.exit( 0 );
            }
         }
      );
   }
}