Answer: Java Applet Program to Track Mouse Cursor Position

1. Overview

In Java AWT/Applet programming, tracking mouse movement is handled by the MouseMotionListener interface from the java.awt.event package.

The MouseMotionListener interface provides two callback methods:

1. mouseMoved(MouseEvent e): Invoked every time the mouse cursor moves within the Applet component boundaries without buttons pressed.
2. mouseDragged(MouseEvent e): Invoked when the mouse is moved while a mouse button is pressed.

[ User Moves Mouse ] ---> [ MouseEvent Fired ] ---> [ mouseMoved(e) extracts X, Y ] ---> [ repaint() ] ---> [ paint(g) draws text ]

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2. Complete Java Applet Code

import java.applet.Applet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;

/*
  <applet code="MouseTrackerApplet.class" width="500" height="400">
  </applet>
*/
public class MouseTrackerApplet extends Applet implements MouseMotionListener {
    // Variables to store mouse cursor coordinates and status
    private int mouseX = 0;
    private int mouseY = 0;
    private String statusMsg = "Move the mouse inside this Applet window...";

    // Initialization method of Applet life cycle
    @Override
    public void init() {
        // Set Applet background and foreground colors
        setBackground(new Color(245, 246, 242));
        setForeground(new Color(27, 36, 48));
        setFont(new Font("SansSerif", Font.BOLD, 14));

        // Register the Applet to listen to mouse motion events
        addMouseMotionListener(this);
    }

    // Invoked when the mouse is moved without pressing any button
    @Override
    public void mouseMoved(MouseEvent e) {
        mouseX = e.getX(); // Get current X coordinate
        mouseY = e.getY(); // Get current Y coordinate
        statusMsg = "Mouse Moving at: X = " + mouseX + ", Y = " + mouseY;
        repaint(); // Request JVM to re-render the Applet screen
    }

    // Invoked when the mouse is dragged with a button pressed
    @Override
    public void mouseDragged(MouseEvent e) {
        mouseX = e.getX();
        mouseY = e.getY();
        statusMsg = "Mouse Dragged at: X = " + mouseX + ", Y = " + mouseY;
        repaint(); // Request JVM to re-render
    }

    // Paint method to render graphics and text on the screen
    @Override
    public void paint(Graphics g) {
        // Display header banner
        g.setColor(new Color(31, 75, 67));
        g.fillRect(20, 20, 460, 40);
        
        g.setColor(Color.WHITE);
        g.drawString("JAVA APPLET MOUSE POSITION TRACKER", 80, 45);

        // Display current cursor coordinates
        g.setColor(new Color(178, 58, 46));
        g.drawString(statusMsg, 30, 100);

        // Draw crosshair indicator at current cursor position
        if (mouseX > 0 && mouseY > 0) {
            g.setColor(Color.BLUE);
            g.drawOval(mouseX - 10, mouseY - 10, 20, 20); // Circle around cursor
            g.drawLine(mouseX - 15, mouseY, mouseX + 15, mouseY); // Horizontal line
            g.drawLine(mouseX, mouseY - 15, mouseX, mouseY + 15); // Vertical line
            
            // Draw small coordinate tooltip near cursor
            g.setFont(new Font("Monospaced", Font.PLAIN, 11));
            g.drawString("(" + mouseX + ", " + mouseY + ")", mouseX + 12, mouseY - 8);
        }
    }
}

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3. HTML Code to Embed the Applet (index.html)

<!DOCTYPE html>
<html>
<head>
  <title>Mouse Motion Applet</title>
</head>
<body>
  <h2>Java Applet: Real-Time Mouse Pointer Coordinates</h2>
  <applet code="MouseTrackerApplet.class" width="500" height="400">
    Your browser does not support Java Applets.
  </applet>
</body>
</html>

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4. Execution Steps

1. Compile the Applet:

   javac MouseTrackerApplet.java
   

2. Run using AppletViewer (JDK tool):

   appletviewer MouseTrackerApplet.java
   

   (Or open index.html in an applet-compatible browser environment).

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5. Method Responsibilities Summary

Method	Role
init()	Configures background color and attaches addMouseMotionListener(this).
mouseMoved(MouseEvent e)	Extracts $(X, Y)$ using e.getX() and e.getY() when cursor is moving freely, then calls repaint().
mouseDragged(MouseEvent e)	Extracts $(X, Y)$ during drag gestures.
paint(Graphics g)	Draws status text and crosshair graphics using coordinates onto the graphics context.