Java Program to Draw Star Shapes

This Java program creates a simple graphical application that draws rows of stars using Java’s Swing library. The program creates a window with rows of stars drawn on it. The Star class defines the shape of a star, the StarPane class handles the drawing logic, and the StarApplet class sets up the main frame for the application. This example showcases basic GUI programming with Swing.

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

public class JavaStarsApplication extends JFrame {

    public JavaStarsApplication() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("Star App");
        setSize(400, 400);

        Container content = getContentPane();
        StarPane pane = new StarPane();
        content.add(pane);

        setLocationRelativeTo(null); // Center the frame
    }

    // Class defining a pane on which to draw
    class StarPane extends JPanel {
        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2D = (Graphics2D) g;
            Star star = new Star(0, 0); // Create a star
            float delta = 60f; // Increment between stars
            float starty = 0f; // Starting y position

            // Draw 3 rows of 4 stars
            for (int yCount = 0; yCount < 3; yCount++) {
                starty += delta; // Increment row position
                float startx = 0f; // Start x position in a row

                // Draw a row of 4 stars
                for (int xCount = 0; xCount < 4; xCount++)
                    g2D.draw(star.atLocation(startx += delta, starty));
            }
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
        	JavaStarsApplication applet = new JavaStarsApplication();
            applet.setVisible(true);
        });
    }
}



class Star
{
  public Star(float x, float y)
  {
    start = new Point2D.Float(x, y);                      // store start point
    createStar();
  }

  // Create the path from start
  void createStar()
  {
    Point2D.Float point = start;
    p = new GeneralPath(GeneralPath.WIND_NON_ZERO);
    p.moveTo(point.x, point.y);
    p.lineTo(point.x + 20.0f, point.y - 5.0f);            // Line from start to A
    point = (Point2D.Float)p.getCurrentPoint();
    p.lineTo(point.x + 5.0f, point.y - 20.0f);            // Line from A to B
    point = (Point2D.Float)p.getCurrentPoint();
    p.lineTo(point.x + 5.0f, point.y + 20.0f);            // Line from B to C
    point = (Point2D.Float)p.getCurrentPoint();
    p.lineTo(point.x + 20.0f, point.y + 5.0f);            // Line from C to D
    point = (Point2D.Float)p.getCurrentPoint();
    p.lineTo(point.x - 20.0f, point.y + 5.0f);            // Line from D to E
    point = (Point2D.Float)p.getCurrentPoint();
    p.lineTo(point.x - 5.0f, point.y + 20.0f);            // Line from E to F
    point = (Point2D.Float)p.getCurrentPoint();
    p.lineTo(point.x - 5.0f, point.y - 20.0f);            // Line from F to g
    p.closePath();                                        // Line from G to start
  }

  Shape atLocation(float x, float y)
  {
    start.setLocation(x, y);                              // Store new start
    p.reset();                                            // Erase current path
    createStar();                                         // create new path
    return p;                                             // Return the path
  }

  // Make the path available
  Shape getShape()
  {
    return p;
  }

  private Point2D.Float start;                           // Start point for star
  private GeneralPath p;                                 // Star path
}

import javax.swing.*;

import java.awt.*;

import java.awt.geom.*;

public class JavaStarsApplication extends JFrame {

public JavaStarsApplication() {

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

setTitle("Star App");

setSize(400, 400);

Container content = getContentPane();

StarPane pane = new StarPane();

content.add(pane);

setLocationRelativeTo(null); // Center the frame

}

// Class defining a pane on which to draw

class StarPane extends JPanel {

@Override

protected void paintComponent(Graphics g) {

super.paintComponent(g);

Graphics2D g2D = (Graphics2D) g;

Star star = new Star(0, 0); // Create a star

float delta = 60f; // Increment between stars

float starty = 0f; // Starting y position

// Draw 3 rows of 4 stars

for (int yCount = 0; yCount < 3; yCount++) {

starty += delta; // Increment row position

float startx = 0f; // Start x position in a row

// Draw a row of 4 stars

for (int xCount = 0; xCount < 4; xCount++)

g2D.draw(star.atLocation(startx += delta, starty));

}

public static void main(String[] args) {

SwingUtilities.invokeLater(() -> {

JavaStarsApplication applet = new JavaStarsApplication();

applet.setVisible(true);

});

}

class Star

{

public Star(float x, float y)

{

start = new Point2D.Float(x, y); // store start point

createStar();

}

// Create the path from start

void createStar()

{

Point2D.Float point = start;

p = new GeneralPath(GeneralPath.WIND_NON_ZERO);

p.moveTo(point.x, point.y);

p.lineTo(point.x + 20.0f, point.y - 5.0f); // Line from start to A