KeyDemo.java

// Fig. 12.36-37: KeyDemo.java
// Key event handling.
import java.awt.Color;
import java.awt.event.KeyListener;
import java.awt.event.KeyEvent;
import javax.swing.JFrame;
import javax.swing.JTextArea;

class KeyDemoFrame extends JFrame implements KeyListener 
{
   private String line1 = ""; // first line of textarea
   private String line2 = ""; // second line of textarea
   private String line3 = ""; // third line of textarea
   private JTextArea textArea; // textarea to display output

   // KeyDemoFrame constructor
   public KeyDemoFrame()
   {
      super("Demonstrating Keystroke Events");

      textArea = new JTextArea(10, 15); // set up JTextArea
      textArea.setText("Press any key on the keyboard...");
      textArea.setEnabled(false);
      textArea.setDisabledTextColor(Color.BLACK);
      add(textArea); // add textarea to JFrame

      addKeyListener(this); // allow frame to process key events
   } 

   // handle press of any key
   @Override
   public void keyPressed(KeyEvent event)
   {
      line1 = String.format("Key pressed: %s", 
        KeyEvent.getKeyText(event.getKeyCode())); // show pressed key
      setLines2and3(event); // set output lines two and three
   }

   // handle release of any key
   @Override
   public void keyReleased(KeyEvent event)
   {
      line1 = String.format("Key released: %s",
         KeyEvent.getKeyText(event.getKeyCode())); // show released key
      setLines2and3(event); // set output lines two and three
   }

   // handle press of an action key
   @Override
   public void keyTyped(KeyEvent event)
   {
      line1 = String.format("Key typed: %s", event.getKeyChar());
      setLines2and3(event); // set output lines two and three
   }

   // set second and third lines of output
   private void setLines2and3(KeyEvent event)
   {
      line2 = String.format("This key is %san action key", 
         (event.isActionKey() ? "" : "not "));

      String temp = KeyEvent.getKeyModifiersText(event.getModifiers());

      line3 = String.format("Modifier keys pressed: %s", 
         (temp.equals("") ? "none" : temp)); // output modifiers

      textArea.setText(String.format("%s\n%s\n%s\n", 
         line1, line2, line3)); // output three lines of text
   }
} // end class KeyDemoFrame

public class KeyDemo 
{
   public static void main(String[] args)
   { 
      KeyDemoFrame keyDemoFrame = new KeyDemoFrame(); 
      keyDemoFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      keyDemoFrame.setSize(350, 100); 
      keyDemoFrame.setVisible(true); 
   } 
} // end class KeyDemo