Answer: Java Applet Application — Color List Box & Scrolling Banner

1. Problem Requirements Breakdown

1. Color List Box (java.awt.List): Displays multiple color names (e.g., Red, Green, Blue, Magenta, Orange) allowing user selection.
2. Scrolling Banner: A text banner that continuously scrolls horizontally from left to right across the Applet screen using a background Thread (Runnable interface).
3. Dynamic Color Change (ItemListener): When the user selects a color from the list, the banner's text/fill color dynamically updates to the selected color.

+-------------------------------------------------------------+
|  [ Color List Box ]         SCROLLING BANNER TEXT ----->    |
|  | Red        |             (Updates X position in Thread)  |
|  | Green      |                                             |
|  | Blue       |             (Selected color updates text)   |
|  | Magenta    |                                             |
+-------------------------------------------------------------+

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2. Complete Java Applet Source Code

import java.applet.Applet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.List;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

/*
  <applet code="ColorBannerApplet.class" width="650" height="350">
  </applet>
*/
public class ColorBannerApplet extends Applet implements Runnable, ItemListener {
    // GUI List Box for selecting colors
    private List colorList;

    // Scrolling Banner properties
    private String bannerText = "Welcome to Bihar Engineering University - Web Technology Exam Archive";
    private int bannerX = -300; // Starting X coordinate (left)
    private int bannerY = 220;  // Y coordinate
    private Color bannerColor = Color.RED; // Default banner color

    // Animation thread
    private Thread animationThread = null;
    private volatile boolean running = false;

    // Applet Initialization
    @Override
    public void init() {
        setLayout(null); // Absolute positioning layout
        setBackground(new Color(245, 246, 242));

        // 1. Create and populate the Color List Box
        colorList = new List(5, false); // 5 visible rows, single selection
        colorList.add("Red");
        colorList.add("Green");
        colorList.add("Blue");
        colorList.add("Magenta");
        colorList.add("Orange");
        colorList.add("Dark Teal");
        colorList.add("Black");

        // Set position and dimensions of the list box
        colorList.setBounds(30, 60, 140, 110);
        colorList.select(0); // Select 'Red' by default

        // Register ItemListener to capture user selection
        colorList.addItemListener(this);

        // Add component to Applet
        add(colorList);
    }

    // Applet Start: Launch Animation Thread
    @Override
    public void start() {
        if (animationThread == null) {
            running = true;
            animationThread = new Thread(this);
            animationThread.start();
        }
    }

    // Animation Loop: Scrolls Banner from Left to Right
    @Override
    public void run() {
        while (running) {
            // Move banner coordinate to the right
            bannerX += 5;

            // When the banner scrolls off the right edge, wrap back to the left
            if (bannerX > getWidth()) {
                bannerX = -gEstimateTextWidth();
            }

            repaint(); // Request screen redraw

            try {
                Thread.sleep(60); // Control scrolling speed (approx 16 FPS)
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                break;
            }
        }
    }

    // Rough text width estimation for wrapping
    private int gEstimateTextWidth() {
        return bannerText.length() * 10;
    }

    // Applet Stop: Stop Thread cleanly
    @Override
    public void stop() {
        running = false;
        animationThread = null;
    }

    // Event Handler for List Box Selection
    @Override
    public void itemStateChanged(ItemEvent e) {
        String selected = colorList.getSelectedItem();
        
        if ("Red".equalsIgnoreCase(selected)) {
            bannerColor = new Color(178, 58, 46);
        } else if ("Green".equalsIgnoreCase(selected)) {
            bannerColor = new Color(34, 139, 34);
        } else if ("Blue".equalsIgnoreCase(selected)) {
            bannerColor = new Color(0, 102, 204);
        } else if ("Magenta".equalsIgnoreCase(selected)) {
            bannerColor = new Color(180, 0, 180);
        } else if ("Orange".equalsIgnoreCase(selected)) {
            bannerColor = new Color(230, 120, 0);
        } else if ("Dark Teal".equalsIgnoreCase(selected)) {
            bannerColor = new Color(31, 75, 67);
        } else if ("Black".equalsIgnoreCase(selected)) {
            bannerColor = Color.BLACK;
        }

        repaint(); // Immediately redraw with new color
    }

    // Screen Paint Rendering
    @Override
    public void paint(Graphics g) {
        // UI Labels
        g.setColor(new Color(27, 36, 48));
        g.setFont(new Font("SansSerif", Font.BOLD, 15));
        g.drawString("Select Banner Color:", 30, 45);

        // Banner Track Area Box
        g.setColor(new Color(235, 237, 231));
        g.fillRect(10, 185, getWidth() - 20, 70);
        g.setColor(new Color(219, 223, 215));
        g.drawRect(10, 185, getWidth() - 20, 70);

        // Draw Scrolling Banner
        g.setColor(bannerColor);
        g.setFont(new Font("Serif", Font.BOLD | Font.ITALIC, 20));
        g.drawString(bannerText, bannerX, bannerY);
    }
}

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3. HTML Deployment File (banner.html)

<!DOCTYPE html>
<html>
<head>
  <title>Color Banner Applet Demo</title>
</head>
<body>
  <h2>Java Applet: Scrolling Banner with Color Selector</h2>
  <applet code="ColorBannerApplet.class" width="650" height="350">
    Java Applets are not supported in your environment.
  </applet>
</body>
</html>

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4. Lifecycle & Flow Explanation

1. init(): Creates the List component, populates color names, sets absolute bounds (setBounds), and registers addItemListener(this).
2. start() / run(): Starts the background thread that continuously increments bannerX by 5 pixels and invokes Thread.sleep(60) to produce smooth left-to-right scrolling.
3. itemStateChanged(): Triggers immediately when a user clicks any color in the list, maps the selection to a java.awt.Color object, and updates bannerColor.
4. paint(): Renders the background container and draws the text at dynamic position (bannerX, bannerY) with bannerColor.