hi friend,

you can add listener by implementing the listener interfaces using implements keyword in Java.

Following code snippet may help you understand how can you add listeners in your classes.

package net.roseindia.swingExample;

import javax.swing.JFrame; import javax.swing.JTextField; import javax.swing.JButton; import javax.swing.JLabel; import java.awt.event.ActionEvent; import java.awt.event.KeyEvent; import java.awt.event.KeyListener; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import java.awt.event.MouseMotionListener; import java.awt.event.MouseWheelEvent; import java.awt.event.MouseWheelListener;

public class TextFiledAndButtonListener implements MouseListener, MouseMotionListener, KeyListener{

JFrame frame;
JButton button;
JTextField textField;
JLabel label;

public void createUI()
{
    frame = new JFrame("Text Field Listener");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(null);
    frame.setSize(400,300);

    label = new JLabel("Enter Text Here ");
    label.setBounds(10,30,100, 20);

    textField = new JTextField();
    textField.setBounds(110, 30, 100, 20);      
    textField.addMouseMotionListener(this);
    textField.addMouseListener(this);       
    textField.addKeyListener(this);

    button = new JButton("Click Here");
    button.setEnabled(false);
    button.setBounds(220,30,100,20);
    frame.add(label);
    frame.add(textField);
    frame.add(button);

    frame.setVisible(true);     
}
@Override
public void mouseDragged(MouseEvent e) {        
}

@Override
public void mouseMoved(MouseEvent e) {
    button.setEnabled(true);        
}

@Override
public void keyTyped(KeyEvent e) {
    button.setEnabled(true);
}

@Override
public void keyPressed(KeyEvent e) {
    System.out.println("Key is Pressed");       
}

@Override
public void keyReleased(KeyEvent e) {
    System.out.println("Key is Released");      
}

public static void main(String args[])
{
    TextFiledAndButtonListener ta = new TextFiledAndButtonListener();
    ta.createUI();
}
@Override
public void mouseClicked(MouseEvent e) {
}
@Override
public void mousePressed(MouseEvent e) {
}
@Override
public void mouseReleased(MouseEvent e) {       
}
@Override
public void mouseEntered(MouseEvent e) {        

}
@Override
public void mouseExited(MouseEvent e) {     
    button.setEnabled(false);       
}

}