How to add mouselistener on random drawn image in java?

Question

I am building a game in Java and I need to add a mouselistener to an random drawn image in my game.

I made the image appear on random places every x seconds, when I click the image I would like to add 1 point to the scoreboard.

My code for the random image adding is:

Random rand = new Random();
private int x = 0;
private int y = 0;

Timer timer = new Timer(700, new ActionListener(){
    @Override
    public void actionPerformed(ActionEvent e) {
        x = rand.nextInt(400);
        y = rand.nextInt(330);
        repaint();
    }
});

public void mousePressed (MouseEvent me) {
       // Do something here
       repaint();
     }

public void paintComponent(Graphics g) {
    super.paintComponent(g);

    g.drawImage(achtergrond, 0, 0, this.getWidth(), this.getHeight(), null);
    //g.drawImage(muisje, 10, 10, null);
    g.drawImage(muisje, x, y, 100, 100, this);
}

I looked on google and found that I need to add a new class with a mouse event, but How do I add this? It's not clear enough because I'm just a beginner in Java.

Answer 1

You need to register a MouseListener for your Gamevenster class. Instead of making the class implement MouseListener, just use a MouseAdapter, where you only have to implement the method mouseClicked. So in your constructor, you something like this

private JLabel scoreLabel = new JLabel("Score: " + score);
private int score = 0;

public Gamevenster() {
    scoreLabel.setFont(new Font("impact", Font.PLAIN, 30));
    scoreLabel.setForeground(Color.WHITE);
    add(scoreLabel);

    addMouseListener(new MouseAdapter(){
        @Override
        public void mouseClicked(MouseEvent e) {
            Point p = e.getPoint();
            int clickX = (int)p.getX();
            int clickY = (int)p.getY();

            if(clickX > x && clickX < x + 100 && clickY > y && clickY  < y + 100) {
                score++;
                scoreLabel.setText("Score: " + score);
            }
        }
    });
}

Answer 2

You know where the image is drawn (x,y) and you know the size of the image (100,100), therefore to tell if the mouse click is inside the image you can do something like this:

public void mousePressed (MouseEvent me) {
    int clickX = me.getXOnScreen();
    int clickY = me.getYOnScreen();


    if(clickX > x && clickX < x+100 && clickY > y && clickY  < y+100) {
        //the image has been clicked
    }
    repaint();
}

The class you're writing can then implement MouseListener.

EDIT in response to comment:

You don't need to link the code to the image, the component that you're writing should implement the mouse listener since this maintains the state and knows where the image is drawn. I would start out by looking at this link and implementing a basic MouseListener to print out the x and y co-ordinates of mouse clicks on your component:

http://docs.oracle.com/javase/tutorial/uiswing/events/mouselistener.html

Example component implementing Mouse Listener:

public class TestComponent extends JComponent implements MouseListener {

    public TestComponent() {
        this.addMouseListener(this);
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        int clickedX = e.getX();
        int clickedY = e.getY();

        System.out.println("User Clicked: " + clickedX + ", " + clickedY);
    }

    @Override
    public void mousePressed(MouseEvent e) {}

    @Override
    public void mouseReleased(MouseEvent e) {}

    @Override
    public void mouseEntered(MouseEvent e) {}

    @Override
    public void mouseExited(MouseEvent e) {}
}