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Starting out with Java

How do I check the status of the CAPS and NUM lock keys? by Ghodmode
Posted: 14 Jul 06

CODE

import java.awt.*;
import java.awt.event.*;

/**
 * This class is an example of one method for checking the
 * state of the CAPS and NUM lock keys before a KeyEvent has
 * been generated.  On some platforms, the
 * Toolkit.getLockingKeyState() method is not supported and
 * throws an UnsupportedOperationException.  The hack
 * creates a new java.awt.Frame, generates some appropriate
 * KeyEvents using java.awt.Robot to be received by an
 * anonymous inner class.  After the hack does it's job, the
 * Frame is disposed to release the memory.
 */
public class capstest {
    public static void main( String [] args ) {
        Frame frame = new Frame( "Checking Locking Key State ..." );

        frame.addKeyListener( new KeyAdapter() {
            public void keyPressed( KeyEvent e ) {
                if ( Character.isLetter(e.getKeyChar()) ) {
                    if ( Character.isUpperCase(e.getKeyChar()) )
                        System.out.println( "CAPS Lock is On" );
                } else {
                    if ( Character.isDigit(e.getKeyChar()) )
                        System.out.println( "NUM Lock is on" );
                }
            }
        });

        // If the frame isn't set visible, the key presses
        // go to the console rather than to the frame
        frame.setVisible( true );

        try {
            Robot robot = new Robot();
            robot.keyPress( KeyEvent.VK_A );
            robot.keyRelease( KeyEvent.VK_A );

            robot.keyPress( KeyEvent.VK_NUMPAD5 );
            robot.keyRelease( KeyEvent.VK_NUMPAD5 );
            frame.dispose();
        } catch ( AWTException e ) {
        }
    }
}

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