Generate 100 random rectangles and ovals

Hello, Im a newbie :))

I'm working with a fairly simple task which I will create a program that draws a number of rectangles and ovals. The size and position of the rectangles and ovals are to be generated randomly.

But I have a problem, my code just draws ONE rectangle or oval, and I think it has something to do with the overlapping. So I need help finding my mistake.

RandomShape

Code:

---

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

public class RandomShape extends JFrame {
        private int n; //Instansvariabel
        public RandomShape() {}
        public RandomShape(int antal) {
                n = antal;
                for(int i=1; i<n; i++)
                        add(generateRandomShape());
                setBackground(Color.white);
                setVisible(true);
                setSize(500,500);
                setDefaultCloseOperation(EXIT_ON_CLOSE);


        }

        public Component generateRandomShape() {
                double r1 = (int)(2*Math.random());
                if                (r1 == 0)
                        return new RandomRect();
                else if (r1 == 1)
                        return new RandomOval();
                else
                        return null;
        }



        public static void main (String[] arg) {
                RandomShape r = new RandomShape(100);
        }
}

---

RandomRect

Code:

---

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

public class RandomRect extends JPanel {
        private int width, height;
        public RandomRect() {
                width  = randomPixel();
                height = randomPixel();
                setPreferredSize(new Dimension(width, height));
                setOpaque(false);

        }

        @Override
        public void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.setColor(Color.red);
                g.fillRect(randomPixel(),randomPixel(), width, height);
        }

        private int randomPixel() {
                int pix = (int)(Math.random()*400);
                return pix;
        }
}

---

RandomOval

Code:

---

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

public class RandomOval extends JPanel {
        private int width, height;
        public RandomOval() {
                width  = randomPixel();
                height = randomPixel();
                setPreferredSize(new Dimension(width, height));
                setOpaque(false);

        }

        @Override
        public void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.setColor(Color.green);
                g.fillOval(randomPixel(),randomPixel(), width, height);
        }

        private int randomPixel() {
                int pix = (int)(Math.random()*400);
                return pix;
        }
}

---

I appreciate all kind of help :)

There are a couple of conceptual errors here. For one you must realize that a JFrame's contentPane uses BorderLayout by default, and so any comopnent added to the JFrame will cover over any that were added before.

But I think more importantly that your RandomRect and RandomOval classes should not extend JPanel but instead should create possibly a Rectangle2D and an Ellipse2D, both of which extend Shape, and your main GUI should hold a JPanel whose paintComponent has been overridden and an ArrayList of Shape or ArrayList<Shape>. Then create your random shapes and place them in the arraylist and in the one JPanel's paintComponent method iterate through the ArrayList drawing each shape.