Java Notes

Example - MouseTest.java

This is a simple demonstration of listening to mouse events on a panel.

We have given the online demo example of the application

You can test the application online if your browser supports java.

The browser will run this example as applet.

This displays two panels to show how the mouse listener depends on the component.

There are two panels in this example. You should be able to see these two panels in the example below.

Here is the demo of the application

The main program / applet

// File:   mousedeme/MouseTest.java
// Description: Main program/applet to demo mouse listeners.
// Author: Fred Swartz
// Date:   2005-02-03, 2000-11-29...2002-11-21
// Possible enhancements: Show other mouse events.


package mousedemo;
import javax.swing.*;

//////////////////////////////////////////////////////// class MouseTest  
public class MouseTest extends JApplet{ 
    //===================================================== constructor
    public MouseTest() {
        add(new DualMousePanel()); 
    }
    
    //====================================================== method main
    public static void main(String[] args) {
        JFrame window = new JFrame("Mouse Demo");
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setContentPane(new DualMousePanel());
        window.pack();
        window.setVisible(true);
    }
}

The content pane of the GUI

// File:   mousedeme/MousePanel.java
// Description: Panel holding two MousePanels.
// Author: Fred Swartz
// Date:   2005-02-03, 2000-11-29...2002-11-21

package mousedemo;

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

////////////////////////////////////////////////// class DualMousePanel
class DualMousePanel extends JPanel {
    //====================================================== constructor
    public DualMousePanel() {
        //--- Create two MousePanels
        MousePanel mp1 = new MousePanel();
        MousePanel mp2 = new MousePanel();
        
        //--- Add borders (note: borders are inside panel)
        Border etched = BorderFactory.createEtchedBorder();
        mp1.setBorder(BorderFactory.createTitledBorder(etched, "Panel 1"));
        mp2.setBorder(BorderFactory.createTitledBorder(etched, "Panel 2"));
        
        //--- Layout the panels
        this.setLayout(new GridLayout(1, 2));
        this.add(mp1);
        this.add(mp2);
    }//end constructor
}

The panel which listens to and shows mouse events

// File:   mousedeme/MousePanel.java
// Description: Panel that listens to mouse events and displays info
//              about some of them.
// Author: Fred Swartz
// Date:   2005-02-03, 2000-11-29...2002-11-21

package mousedemo;

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

/////////////////////////////////////////////////////// class MousePanel
class MousePanel extends JPanel implements MouseListener, MouseMotionListener {
    
   //================================================ instance variables
    private int m_lastClickedX = 0;  // x coord of mouse click 
    private int m_lastClickedY = 0;  // y coord of mouse click
    private int m_lastMovedX   = 0;  // x coord of mouse move 
    private int m_lastMovedY   = 0;  // y coord of mouse move
    
   
    //====================================================== constructor
    public MousePanel() {
        this.setBackground(Color.white);
        this.setPreferredSize(new Dimension(200, 200));
        //--- Add the mouse listeners.
        this.addMouseListener(this);       // listen to mouse events
        this.addMouseMotionListener(this); // listen to moves and drags
    }
    
    
    //============================================ method paintComponent
    public void paintComponent(Graphics g) {
        super.paintComponent(g);  // paint background and borders
        g.drawString("Last click: x=" + m_lastClickedX 
                      + ", y=" + m_lastClickedY , 10, 30);
        g.drawString("x=" + m_lastMovedX   + ", y=" + m_lastMovedY 
                      , m_lastMovedX, m_lastMovedY);
    }
    

    //============================================ listener mouseClicked
    public void mouseClicked(MouseEvent e) {
        m_lastClickedX = e.getX(); // Save the x coordinate of the click
        m_lastClickedY = e.getY(); // Save the y coordinate of the click
        this.repaint();            // Paint the panel with the new values.
    }
    
  
    //============================================== listener mouseMoved
    public void mouseMoved(MouseEvent e) {
        m_lastMovedX = e.getX();
        m_lastMovedY = e.getY();
        this.repaint();
    }
  
  
    //========================================================== ignored
    //==== the other motion events must be here, but do nothing.
    public void mouseDragged (MouseEvent e) {}  // ignore
    //==== these "slow" mouse events are ignored.
    public void mouseEntered (MouseEvent e) {}  // ignore
    public void mouseExited  (MouseEvent e) {}  // ignore
    public void mousePressed (MouseEvent e) {}  // ignore
    public void mouseReleased(MouseEvent e) {}  // ignore
}

Copyleft 2005 Fred Swartz MIT License

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