How Do I Set the Focus so my GUI Can Read Key Events?

KevinSimonson <>
Tue, 30 Nov 2010 08:29:18 -0800 (PST)
I'm trying to build a GUI that can read key events and tell which
character was keyed in. I wrote the following code to test my ability
to do that, but when I execute it, click in the <JPanel>, and type in
characters, nothing happens. It seems like I need to set the focus on
the GUI, but I don't remember precisely how to do that. Is there
anybody out there who can see what I'm doing wrong, and how I can get
the characters I enter displayed on my GUI? Thanks in advance for any
pointers you can give me.

Kevin S

import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Graphics;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.event.KeyListener;
import java.awt.event.KeyEvent;

public class KlBug extends JPanel implements KeyListener
  private Font courier12;
  private char[] enteredString;
  private int enteredSize;

  private KlBug ()
    courier12 = new Font( "Courier", Font.PLAIN, 12);
    enteredString = new char[ 1000];
    enteredSize = 0;
    setPreferredSize( new Dimension( 800, 600));
    addKeyListener( this);

  public void paintComponent ( Graphics page)
    super.paintComponent( page);
    page.setFont( courier12);
    int xLctn = 60;
    int yLctn = 60;
    for (int ec = 0; ec < enteredSize; ec++)
    { if (enteredString[ ec] != '\n')
      { page.drawString( "" + enteredString[ ec], xLctn, yLctn + 10);
        xLctn += 7;
      { yLctn += 12;
        xLctn = 60;

  public void keyPressed ( KeyEvent evnt) {}
  public void keyReleased ( KeyEvent evnt) {}

  public void keyTyped ( KeyEvent evnt)
    System.out.println( "Key '" + evnt.getKeyChar() + "' typed.");
    enteredString[ enteredSize++] = evnt.getKeyChar();

  public static void main ( String[] arguments)
    KlBug kb = new KlBug();
    JFrame kbFrame = new JFrame( "KlBug");
    kbFrame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE);
    kbFrame.getContentPane().add( kb);
    kbFrame.setVisible( true);

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