Buttons and actionlistener help.

Question

the following code has 2 buttons, how would i use a button to get me differnt graphics but inside the same window,
say i clicked next the graphics would be slightly altered which I will do but it wont open a new window it will be in the same window, but different shapes.
I am having trouble with action listeners and really need help in how they work iv read up but dont understand, and how this would be implemented for this.
much help would be appreciated.
import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.RenderingHints;
import java.awt.Stroke;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class square extends JPanel
    public square()
        setPreferredSize(new Dimension(800, 700));
        int eb = 80;
        setBorder(BorderFactory.createEmptyBorder(eb, eb, eb, eb));
        setLayout(new BorderLayout(5, 10));
       JPanel buttonPanel = createButtonPanel();
         add(buttonPanel, BorderLayout.SOUTH);
    private JPanel createButtonPanel()
        JPanel bp = new JPanel();
        bp.setOpaque(false);
               JButton btn2 = new JButton("<-  Back Step ");
                JButton btn = new JButton("Next Step   ->");
                bp.add(btn2);
                bp.add(btn);
        return bp;
    @Override
    protected void paintComponent(Graphics g)
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);
        Rectangle2D rect = new Rectangle2D.Double(250, 150, 100, 100);
        Rectangle2D     rect2 = new Rectangle2D.Double(400, 150, 100, 100);
         Rectangle2D     rect3 = new Rectangle2D.Double(550, 150, 100, 100);
         Rectangle2D     rect4 = new Rectangle2D.Double(250, 300, 100, 100);
         Rectangle2D     rect5 = new Rectangle2D.Double(400, 300, 100, 100);
         Rectangle2D     rect6 = new Rectangle2D.Double(550, 300, 100, 100);
         Rectangle2D     rect7 = new Rectangle2D.Double(250, 450, 100, 100);
         Rectangle2D     rect8 = new Rectangle2D.Double(400, 450, 100, 100);
         Rectangle2D     rect9 = new Rectangle2D.Double(550, 450, 100, 100);
         g.drawString("b0,0", 300, 130);
        g.drawString("b1,0", 300, 110);
         g.drawString("b2,0", 300, 90);
             g.drawString("b0,1", 450, 110);
        g.drawString("b1,1", 450, 90);
        g.drawString("b2,1", 450, 70);
             g.drawString("b0,2", 600, 90);
        g.drawString("b1,2", 600, 70);
        g.drawString("b2,2", 600, 50);
         g.drawString("a0,0", 200, 200);
        g.drawString("a1,0", 150, 200);
         g.drawString("a2,0", 100, 200);
             g.drawString("a0,1", 150, 350);
        g.drawString("a1,1", 100, 350);
        g.drawString("a2,1", 50, 350);
               g.drawString("a0,2", 100, 500);
        g.drawString("a1,2", 50, 500);
        g.drawString("a2,2", 15, 500);
        g2.setPaint(Color.black);
        g2.draw(rect);
        g2.draw(rect);
          g2.draw(rect2);
         g2.draw(rect3);
          g2.draw(rect4);
         g2.draw(rect5);
          g2.draw(rect6);
         g2.draw(rect7);
          g2.draw(rect8);
          g2.draw(rect9);
        Stroke oldStroke = g2.getStroke();
        g2.setStroke(new BasicStroke(5));
        g2.setStroke(oldStroke);
    private static void createAndShowUI()
        JFrame frame = new JFrame("Matrix Multiplication - Step by Step ");
        frame.getContentPane().add(new square());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    public static void main(String[] args)
        java.awt.EventQueue.invokeLater(new Runnable()
            public void run()
                createAndShowUI();
}

Answer 1

ok I had a look over it, I got this
import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.RenderingHints;
import java.awt.Stroke;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class square extends JPanel implements ActionListener
    public square()
        setPreferredSize(new Dimension(800, 700));
        int eb = 80;
        setBorder(BorderFactory.createEmptyBorder(eb, eb, eb, eb));
        setLayout(new BorderLayout(5, 10));
       JPanel buttonPanel = createButtonPanel();
         add(buttonPanel, BorderLayout.SOUTH);
  public void actionPerformed(ActionEvent e) {
        System.out.println("hello");
    private JPanel createButtonPanel()
        JPanel bp = new JPanel();
        bp.setOpaque(false);
               JButton btn2 = new JButton("<-  Back Step ");
                JButton btn = new JButton("Next Step   ->");
                bp.add(btn2);
                bp.add(btn);
         btn.addActionListener(this);
        return bp;
    @Override
    protected void paintComponent(Graphics g)
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);
        Rectangle2D rect = new Rectangle2D.Double(250, 150, 100, 100);
        Rectangle2D     rect2 = new Rectangle2D.Double(400, 150, 100, 100);
         Rectangle2D     rect3 = new Rectangle2D.Double(550, 150, 100, 100);
         Rectangle2D     rect4 = new Rectangle2D.Double(250, 300, 100, 100);
         Rectangle2D     rect5 = new Rectangle2D.Double(400, 300, 100, 100);
         Rectangle2D     rect6 = new Rectangle2D.Double(550, 300, 100, 100);
         Rectangle2D     rect7 = new Rectangle2D.Double(250, 450, 100, 100);
         Rectangle2D     rect8 = new Rectangle2D.Double(400, 450, 100, 100);
         Rectangle2D     rect9 = new Rectangle2D.Double(550, 450, 100, 100);
         g.drawString("b0,0", 300, 130);
        g.drawString("b1,0", 300, 110);
         g.drawString("b2,0", 300, 90);
             g.drawString("b0,1", 450, 110);
        g.drawString("b1,1", 450, 90);
        g.drawString("b2,1", 450, 70);
             g.drawString("b0,2", 600, 90);
        g.drawString("b1,2", 600, 70);
        g.drawString("b2,2", 600, 50);
         g.drawString("a0,0", 200, 200);
        g.drawString("a1,0", 150, 200);
         g.drawString("a2,0", 100, 200);
             g.drawString("a0,1", 150, 350);
        g.drawString("a1,1", 100, 350);
        g.drawString("a2,1", 50, 350);
               g.drawString("a0,2", 100, 500);
        g.drawString("a1,2", 50, 500);
        g.drawString("a2,2", 15, 500);
        g2.setPaint(Color.black);
        g2.draw(rect);
        g2.draw(rect);
          g2.draw(rect2);
         g2.draw(rect3);
          g2.draw(rect4);
         g2.draw(rect5);
          g2.draw(rect6);
         g2.draw(rect7);
          g2.draw(rect8);
          g2.draw(rect9);
        Stroke oldStroke = g2.getStroke();
        g2.setStroke(new BasicStroke(5));
        g2.setStroke(oldStroke);
    private static void createAndShowUI()
        JFrame frame = new JFrame("Matrix Multiplication - Step by Step ");
        frame.getContentPane().add(new square());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    public static void main(String[] args)
        java.awt.EventQueue.invokeLater(new Runnable()
            public void run()
                createAndShowUI();
}it produces hello once I click the button, but how would I produce the same frame once the button is clicked, not a new frame, the same one iv got with slight adjustments inside it..which i will do.