CODEWITHSUNDEEP
javaswingjframemouselistener
theman22
theman22

Reputation: 35

MouseListener on JFrame only listens borders

I am trying to create a JFrame that will register MouseEvents for my game. However, when the following code is run, the console only prints "in" and "out" when you drag the frame border and then move your cursor. Very confusing. I tried adding the component glassPane and then adding the MouseListener there but it still is unsuccessful. 

import java.awt.Dimension;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JFrame;

public class Window extends JFrame implements MouseListener {

    private static final long serialVersionUID = -240840600533728354L;

    public Window(int width, int height, String title, Game game) {
        JFrame frame = new JFrame(title);

        frame.setPreferredSize(new Dimension(width, height));
        frame.setSize(new Dimension(width, height));
        frame.setMaximumSize(new Dimension(width, height));
        frame.setMinimumSize(new Dimension(width, height));

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(false);
        frame.setLocationRelativeTo(null);
        frame.add(game);
        frame.setVisible(true);
        frame.addMouseListener(this);
        game.start();
    }

    @Override
    public void mouseExited(MouseEvent e) {
        System.out.println("out");
    }

    @Override
    public void mouseClicked(MouseEvent e) {}

    @Override
    public void mousePressed(MouseEvent e) {}

    @Override
    public void mouseReleased(MouseEvent e) {}

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

Upvotes: 1

Views: 425

Answers (2)

Hovercraft Full Of Eels
Hovercraft Full Of Eels

Reputation: 285440

I think that the last thing that you want to do is to add the MouseListener to the JFrame, since the JFrame shouldn't have this responsibility. It's responsibility should be to hold and display the components that are added to it, and it is likely one of those components, probably the one that displays the game's active view, very likely a JPanel, which should get this MouseListener.

Some side notes:

  • I try to avoid extending JFrame and recommend that you do the same, unless you plan on overriding its behaviors (methods). Instead, create the JFrame when you need it.
  • Your Window class in fact extends JFrame, but does not even create a displayable this object, so yet another (and stronger) reason not to have this class extend JFrame.
  • I recommend having the Game object specify its own size by overriding its getPreferredSize() method, and then letting the JFrame achieve this by calling pack() on the JFrame after adding all components to it.
  • Note that core Java already has a Window class, and you may wish to avoid having your class share names with core Java classes, just in case you wish to use one of those core classes later, and wish to avoid running into name clashes.

Upvotes: 2

Andrew Thompson
Andrew Thompson

Reputation: 168845

Add the MouseListener to the Game (that actually needs the mouse events) rather than the JFrame (which doesn't, and adds a complication with the frame decorations/border).

Upvotes: 2

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