I'm writing a simple program in Java which includes a KeyListener with the following overriding they KeyTyped method:
@Override
public void keyTyped(KeyEvent e)
{
int key = e.getKeyCode();
System.out.println("TEST");
if (key == KeyEvent.VK_KP_LEFT || key == KeyEvent.VK_LEFT)
{
System.out.println("LEFT");
//Call some function
}
else if (key == KeyEvent.VK_KP_RIGHT || key == KeyEvent.VK_RIGHT)
{
System.out.println("RIGHT");
//Call some function
}
}
When I type anything other than the arrow keys (e.g. "a"), it prints TEST
as it should. However, when I type a numpad arrowkey, it only prints TEST
and when I type a standard arrow key it doesn't print anything at all. Is this possibly because I'm on a laptop, or have I just made a silly mistake somewhere?
Yep, you'll see the arrow keys respond to keyPressed and keyReleased, not keyTyped. My SSCCE:
import java.awt.Dimension;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.*;
public class ArrowTest extends JPanel {
private static final int PREF_W = 400;
private static final int PREF_H = PREF_W;
public ArrowTest() {
setFocusable(true);
requestFocusInWindow();
addKeyListener(new KeyAdapter() {
@Override
public void keyTyped(KeyEvent e) {
myKeyEvt(e, "keyTyped");
}
@Override
public void keyReleased(KeyEvent e) {
myKeyEvt(e, "keyReleased");
}
@Override
public void keyPressed(KeyEvent e) {
myKeyEvt(e, "keyPressed");
}
private void myKeyEvt(KeyEvent e, String text) {
int key = e.getKeyCode();
System.out.println("TEST");
if (key == KeyEvent.VK_KP_LEFT || key == KeyEvent.VK_LEFT)
{
System.out.println(text + " LEFT");
//Call some function
}
else if (key == KeyEvent.VK_KP_RIGHT || key == KeyEvent.VK_RIGHT)
{
System.out.println(text + " RIGHT");
//Call some function
}
}
});
}
@Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
private static void createAndShowGui() {
ArrowTest mainPanel = new ArrowTest();
JFrame frame = new JFrame("ArrowTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
So to solve this, override keyPressed rather than keyTyped if you want to listen to arrow events.
Or for an even better solution: use Key Bindings
Edit
My Key Bindings version:
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.*;
@SuppressWarnings("serial")
public class ArrowTest extends JPanel {
private static final int PREF_W = 400;
private static final int PREF_H = PREF_W;
public ArrowTest() {
ActionMap actionMap = getActionMap();
int condition = JComponent.WHEN_IN_FOCUSED_WINDOW;
InputMap inputMap = getInputMap(condition);
for (Direction direction : Direction.values()) {
inputMap.put(direction.getKeyStroke(), direction.getText());
actionMap.put(direction.getText(), new MyArrowBinding(direction.getText()));
}
}
private class MyArrowBinding extends AbstractAction {
public MyArrowBinding(String text) {
super(text);
putValue(ACTION_COMMAND_KEY, text);
}
@Override
public void actionPerformed(ActionEvent e) {
String actionCommand = e.getActionCommand();
System.out.println("Key Binding: " + actionCommand);
}
}
@Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
private static void createAndShowGui() {
ArrowTest mainPanel = new ArrowTest();
JFrame frame = new JFrame("ArrowTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
enum Direction {
UP("Up", KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0)),
DOWN("Down", KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0)),
LEFT("Left", KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0)),
RIGHT("Right", KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0));
Direction(String text, KeyStroke keyStroke) {
this.text = text;
this.keyStroke = keyStroke;
}
private String text;
private KeyStroke keyStroke;
public String getText() {
return text;
}
public KeyStroke getKeyStroke() {
return keyStroke;
}
@Override
public String toString() {
return text;
}
}