Example of Java KeyListener
Example 1:
Below is the implementation of the Java KeyListener:
Java
// Java program to demonstrate textfield and // display typed text using KeyListener import java.awt.*; import java.awt.event.*; public class KeyListenerExample extends Frame implements KeyListener { private TextField textField; private Label displayLabel; // Constructor public KeyListenerExample() { // Set frame properties setTitle( "Typed Text Display" ); setSize( 400 , 200 ); setLayout( new FlowLayout()); // Create and add a TextField for text input textField = new TextField( 20 ); textField.addKeyListener( this ); add(textField); // Create and add a Label to display typed text displayLabel = new Label( "Typed Text: " ); add(displayLabel); // Ensure the frame can receive key events setFocusable( true ); setFocusTraversalKeysEnabled( false ); // Make the frame visible setVisible( true ); } // Implement the keyPressed method @Override public void keyPressed(KeyEvent e) { // You can add custom logic here if needed } // Implement the keyReleased method @Override public void keyReleased(KeyEvent e) { // You can add custom logic here if needed } // Implement the keyTyped method @Override public void keyTyped(KeyEvent e) { char keyChar = e.getKeyChar(); displayLabel.setText( "Typed Text: " + textField.getText() + keyChar); } public static void main(String[] args) { new KeyListenerExample(); } } |
Output:
Example 2:
Below is the implementation of Java KeyListener:
Java
//Java program to demonstrate keyPressed, // keyReleased and keyTyped method import java.awt.*; import java.awt.event.*; public class KeyListenerExample extends Frame implements KeyListener { private TextField textField; private Label displayLabel; // Constructor public KeyListenerExample() { // Set frame properties setTitle( "Typed Text Display" ); setSize( 400 , 200 ); setLayout( new FlowLayout()); // Create and add a TextField for text input textField = new TextField( 20 ); textField.addKeyListener( this ); add(textField); // Create and add a Label to display typed text displayLabel = new Label( "Typed Text: " ); add(displayLabel); // Ensure the frame can receive key events setFocusable( true ); setFocusTraversalKeysEnabled( false ); // Make the frame visible setVisible( true ); } // Implement the keyPressed method @Override public void keyPressed(KeyEvent e) { int keyCode = e.getKeyCode(); System.out.println( "Key Pressed: " + KeyEvent.getKeyText(keyCode)); } // Implement the keyReleased method @Override public void keyReleased(KeyEvent e) { int keyCode = e.getKeyCode(); System.out.println( "Key Released: " + KeyEvent.getKeyText(keyCode)); } // Implement the keyTyped method @Override public void keyTyped(KeyEvent e) { char keyChar = e.getKeyChar(); System.out.println( "Key Typed: " + keyChar); displayLabel.setText( "Typed Text: " + textField.getText() + keyChar); } public static void main(String[] args) { new KeyListenerExample(); } } |
Output:
Terminal Showing the Key Presses:
Java KeyListener in AWT
The Java KeyListener in the Abstract Window Toolkit (AWT) is a fundamental tool for achieving this. The KeyListener Interface is found in “java.awt.event” package. In this article, we’ll explore what the KeyListener is, and its declaration methods, and supply examples with explanatory comments.