The document describes a Java code snippet that controls two buttons and a label. The summarized solution modifies the code to use separate listener classes for each button, so that clicking the left button sets the label to "Left" and clicking the right button sets the label to "Right".

1. Modify the code below so that two separate listener classes are used - one for each of the two
buttons. public class LettRight Panel extends JPanel {private JButton left, right; private JLabel
label; public LeftRightPanel () {left = new JButton ("Left"); right = new JButton ("Right");
label = new JLabel("Left/Right"); ButtonListener listener = new ButtonListener();
left.addActionListener (listener); right.addActionLiatener (listener); add (left); add (right); add
(label);} private class ButtonListener implements ActionListener public void actionPerformed
(ActionEvent event) {if (event.getSource() == left) label.setText("Left"); else
label.setText("Right");}}}
Solution
Hi,
I have modifief the code and highlighted the code changes below.
LeftRightPanel.java
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class LeftRightPanel extends JPanel{
private JButton left, right;
private JLabel label;
public LeftRightPanel(){
left = new JButton("Left");
right = new JButton("Right");
label = new JLabel("Left/Right");
LeftButtonListener leftListener = new LeftButtonListener();
RightButtonListener rightListener = new RightButtonListener();
left.addActionListener(leftListener);
right.addActionListener(rightListener);
add(left);
add(right);
add(label);
}
private class LeftButtonListener implements ActionListener{

2. public void actionPerformed(ActionEvent e) {
label.setText("Left");
}
}
private class RightButtonListener implements ActionListener{
public void actionPerformed(ActionEvent e) {
label.setText("Right");
}
}
}