Credits

Monday, February 15, 2010

Java's KeyListener

Events are handled in Java through Event handlers and listeners. For every listener, there is a corresponding event handler. There are methods associated with this interface and shall be worked with even it means doing nothing.


Below is an application of key listener. 

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/*responding to user input*/
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;

public class KeyViewerGUI extends JFrame implements KeyListener {
JTextField keyText = new JTextField(80);
JLabel keyLabel = new JLabel("Press any key in the text field.");

KeyViewerGUI() {
super("KeyViewer");
setSize(350, 100);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
keyText.addKeyListener(this);
BorderLayout bord = new BorderLayout();
setLayout(bord);
add(keyLabel, BorderLayout.NORTH);
add(keyText, BorderLayout.CENTER);
setVisible(true);
}

public void keyTyped(KeyEvent input) {
char key = input.getKeyChar();
keyLabel.setText("You pressed " + key);
}

public void keyPressed(KeyEvent txt) {
// do nothing
}

public void keyReleased(KeyEvent txt) {
// do nothing
}

public static void main(String[] arguments) {
KeyViewerGUI frame = new KeyViewerGUI();
}
}

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