Question

I need to preface this with my instructor doesn’t let us use IDE’s. We use TextPad. I want to click on this label and it then change from “H” to “T”. Currently when I click the label does nothing. What am I forgetting?

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;


public class Lab3Label extends JLabel implements MouseListener {
    int count = 0;
    boolean flag = true;

    public Lab3Label (int i) {
        setLayout(new BorderLayout());
        count = i;
        this.setText("H");
        this.setFont(new Font("Serif", Font.PLAIN, 60));
        this.setBorder(BorderFactory.createLineBorder(Color.black));
    }

    public void mouseReleased(MouseEvent e)
        {

            if(flag){
                this.setText("H");
                flag = false;
            }

            else{
                this.setText("T");
                flag = true;
            }
        }

    public void mouseExited(MouseEvent e){}
    public void mouseClicked(MouseEvent e){}
    public void mousePressed(MouseEvent e){}
    public void mouseMoved(MouseEvent e){}
    public void mouseEntered(MouseEvent e){}


}

Answer 1

Your JLabel implements MouseListener, but you also need to tell the JLabel to send events to itself. At the end of the constructor you’ll need to say

addMouseListener(this);

This makes more sense if you remember that you can make any class into a MouseListener, and you’d have to connect your listener to your JLabel. The fact that the JLabel is its own listener doesn’t absolve you of this responsibility.