TwoButtons.java

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

public class TwoButtons {
    JFrame frame;
    JLabel label;

    public static void main (String[] args) {
        TwoButtons gui = new TwoButtons();
        gui.go();
    }

    public void go() {
        frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JButton labelButton = new JButton("Change Label");
        labelButton.addActionListener(new LabelButtonListener());

        JButton colorButton = new JButton("Change Circle");
        colorButton.addActionListener(new ColorButtonListener());

        label = new JLabel("I'm a label");
        MyDrawPanel drawPanel = new MyDrawPanel();

        frame.getContentPane().add(BorderLayout.SOUTH, colorButton);
        frame.getContentPane().add(BorderLayout.CENTER, drawPanel);
        frame.getContentPane().add(BorderLayout.EAST, labelButton);
        frame.getContentPane().add(BorderLayout.WEST, label);

        frame.setSize(420,300);
        frame.setVisible(true);
    }

    class LabelButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            label.setText("Ouch!");
        }
    } // close inner class

    class ColorButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            frame.repaint();
        }
    }  // close inner class

}

class MyDrawPanel extends JPanel {

    public void paintComponent(Graphics g) {

        g.fillRect(0,0,this.getWidth(), this.getHeight());

        // make random colors to fill with
        int red = (int) (Math.random() * 255);
        int green = (int) (Math.random() * 255);
        int blue = (int) (Math.random() * 255);

        Color randomColor = new Color(red, green, blue);
        g.setColor(randomColor);
        g.fillOval(70,70,100,100);
    }
}