MouseListener on JFrame never being called

I'm trying to use a MouseListener to see when something is clicked in my JFrame, but none of the events (mouseClicked, mouseEntered, etc) are ever called. I'm using a Canvas to draw the game onto the JFrame and I'm wondering if that could be the issue, but I'm not sure how to fix it. I was following this tutorial and my code looks almost exactly the same.

Here's my JFrame class:

public class Display extends JFrame implements MouseListener {
    public static int width;
    public static int height;

    public static final int CARD_SIZE = 100;
    public static final int BUFFER_SIZE = 25;
    public static final int TITLE_SIZE = 50;

    private JFrame frame;
    private MyCanvas canvas;

    public Display (int r, int c, Card[][] b) {
        width = c*CARD_SIZE + (c+2)*BUFFER_SIZE;
        System.out.println(width);
        height = r*CARD_SIZE + (r+1)*BUFFER_SIZE + TITLE_SIZE*2;
        System.out.println(height);
        frame = new JFrame("Matching Game");
        frame.setLayout(null);
        frame.setSize(width, height);
        frame.setResizable(false);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setFocusable(true);

        frame.addMouseListener(this);

        canvas = new MyCanvas(b);
        frame.add(canvas);
        frame.setVisible(true);
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        System.out.println("Mouse Clicked at X: " + e.getX() + " - Y: " + e.getY());
    }
    @Override
    public void mouseEntered(MouseEvent e) {
        System.out.println("Mouse Entered frame at X: " + e.getX() + " - Y: " + e.getY());
    }
    @Override
    public void mouseExited(MouseEvent e) {
        System.out.println("Mouse Exited frame at X: " + e.getX() + " - Y: " + e.getY());
    }
    @Override
    public void mousePressed(MouseEvent e) {
        System.out.println("Mouse Pressed at X: " + e.getX() + " - Y: " + e.getY());
    }
    @Override
    public void mouseReleased(MouseEvent e) {
        System.out.println("Mouse Released at X: " + e.getX() + " - Y: " + e.getY());
    }
}

The primary thing you were doing wrong was to extend JFrame and also create an explicit instance of one. Do it as follows.

import java.awt.Dimension;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

import javax.swing.JFrame;
import javax.swing.JPanel;


public class Display  implements MouseListener {
    public static int width;
    public static int height;

    public static final int CARD_SIZE = 100;
    public static final int BUFFER_SIZE = 25;
    public static final int TITLE_SIZE = 50;

    private JPanel canvas;
    private JFrame frame;

    public static void main(String[] args) {
        new Display(3,3,new int[3][3]);

    }

    public Display (int r, int c, int[][] b) {
        width = c*CARD_SIZE + (c+2)*BUFFER_SIZE;
        System.out.println(width);
        height = r*CARD_SIZE + (r+1)*BUFFER_SIZE + TITLE_SIZE*2;
        System.out.println(height);
        frame = new JFrame("Matching Game");
//        frame.setLayout(null);
//        frame.setSize(width, height);
        frame.setResizable(false);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setFocusable(true);

        frame.addMouseListener(this);

        canvas = new JPanel();
        canvas.setPreferredSize(new Dimension(width,height));

        frame.add(canvas);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        System.out.println("Mouse Clicked at X: " + e.getX() + " - Y: " + e.getY());
    }
    @Override
    public void mouseEntered(MouseEvent e) {
        System.out.println("Mouse Entered frame at X: " + e.getX() + " - Y: " + e.getY());
    }
    @Override
    public void mouseExited(MouseEvent e) {
        System.out.println("Mouse Exited frame at X: " + e.getX() + " - Y: " + e.getY());
    }
    @Override
    public void mousePressed(MouseEvent e) {
        System.out.println("Mouse Pressed at X: " + e.getX() + " - Y: " + e.getY());
    }
    @Override
    public void mouseReleased(MouseEvent e) {
        System.out.println("Mouse Released at X: " + e.getX() + " - Y: " + e.getY());
    }
}

Points to consider

• don't extend JFrame, just use an instance.
• Canvas is old. I recommend using a JPanel to hold the components and/or painting
• frame.setLocationRelativeTo(null) centers your frame on the screen.
• Since I don't have the Card class I used int[][] to demonstrate this.
• Anything else I did, check out the API documentation for explanations.

For more on GUI's, etc, check out the Java Tutorials