Displaying Dots in a Frame

Displaying Dots in a Frame

1. What Is a Dot? (beginner)

Dot = tiny filled oval (1-4 px!) or single-pixel line. Scatter random dots = starfield/confetti! Uses fillOval + Random.

2. Code — 100 Random Dots (exam program!)

import java.awt.*;
import java.util.Random;
class Dots extends Frame {
    Random r = new Random();
    Dots() { setSize(300, 200); setVisible(true); }
    public void paint(Graphics g) {
        g.setColor(Color.BLUE);
        for (int i = 0; i < 100; i++) {
            int x = 10 + r.nextInt(280); // random x!
            int y = 50 + r.nextInt(140); // random y (below title!)
            g.fillOval(x, y, 3, 3);      // 3px dot!
        }
    }
}
new Dots();

Single dot: g.drawLine(x, y, x, y); (1px!) or g.fillRect(x, y, 2, 2);.

3. Animation Taste (beyond static!)

Move dots: store list, Thread updates + repaint() every 100ms (game loop preview!).

4. Traps

• Dots vanish on resize (repaint redraws RANDOM new!). Store points to keep!
• y < 50 hidden under title (start lower!).
• fillOval needs width/height ≥ 1 (0 = invisible!).

5. Exam Points

• Random-dots program — 5 marks, frequent.
• fillOval dot trick + repaint — 3 marks, frequent.