Karel Hrkal

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

public class Simple2DApp {

    private static Rectangle r1, r2;
    private static JPanel drawPanel;

    public static void main(String[] args) {

        r1 = new Rectangle(30, 20, 60, 30);
        r2 = new Rectangle(360, 130, 120, 205);

        JFrame mainFrame = new JFrame("Easy 2D Java App");
        mainFrame.setBounds(50, 50, 800, 600);
        mainFrame.setLayout(null);

        drawPanel = new MyPanel(Color.red, Color.blue);
        drawPanel.setBounds(20, 20, 750, 420);
        drawPanel.setBackground(Color.white);

        ActionListener listener = new MyActionListener();

        Button increaseBut = new Button("Increase");
        increaseBut.setActionCommand("increase");
        increaseBut.addActionListener(listener);
        increaseBut.setBounds(30, 510, 100, 35);

        Button decreaseBut = new Button("Decrease");
        decreaseBut.setActionCommand("decrease");
        decreaseBut.addActionListener(listener);
        decreaseBut.setBounds(160, 510, 100, 35);

        Button switchBut = new Button("Switch");
        switchBut.setActionCommand("switch");
        switchBut.addActionListener(listener);
        switchBut.setBounds(300, 510, 100, 35);

        mainFrame.add(drawPanel);
        mainFrame.add(increaseBut);
        mainFrame.add(decreaseBut);
        mainFrame.add(switchBut);

        mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        mainFrame.setVisible(true);

    }

    private static class MyPanel extends JPanel {
        private final Color r1Color, r2Color;

        public MyPanel(Color r1Color, Color r2Color) {
            this.r1Color = r1Color;
            this.r2Color = r2Color;
        }

        public void paint(Graphics g) {
            super.paint(g);
            g.setColor(r1Color);
            g.fillRect(r1.x, r1.y, r1.width, r1.height);
            g.setColor(r2Color);
            g.fillRect(r2.x, r2.y, r2.width, r2.height);
        }

    }

    private static class MyActionListener implements ActionListener {

        public void actionPerformed(ActionEvent e) {
            if(e.getActionCommand().equals("increase")) {
                r1.height += 2;
                r1.width += 2;
                r1.x--;
                r1.y--;
                r2.height += 2;
                r2.width += 2;
                r2.x--;
                r2.y--;
            }
            else if(e.getActionCommand().equals("decrease")) {
                r1.height -= 2;
                r1.width -= 2;
                r1.x++;
                r1.y++;
                r2.height -= 2;
                r2.width -= 2;
                r2.x++;
                r2.y++;
            }
            else if(e.getActionCommand().equals("switch")) {
                Rectangle buff = r1;
                r1 = r2;
                r2 = buff;
            }
            drawPanel.repaint();
        }

    }

}