Scrollbars and Mouse monitoring in a JFrame

Question

class Akim extends JFrame
     public Akim()
          super("Drawing lines");
          pack();
          setSize(640,640);
          setVisible(true);
     public void paint(Graphics g)
          super.paint(g);
          g.setColor(new Color(200,200,250));
          g.fillRect(40,40,400,400);
          g.setColor(new Color(255,255,255));
          for(int i = 2; i<=22; i++)
               g.drawLine(20*i,40,20*i,440);
          for (int i=1;i<=22;i++)
               g.drawLine(40,20*i,440,20*i);
class blah
     public static void main(String[] args)
          Akim me = new Akim();
          me.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}I am keeping the size down because if it gets bigger it goes off the screen. I would like to know how to add scrollbars.
I would also like to display something whenever someone clicks in one of the squares. How do I get the location where the mouse was pressed?
I only started working with JFrames yesterday so please keep it simple(if possible).
Thanks for any help.

Answer 1

Here is an example with a little of everything I mentioned:import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.net.URL;
import javax.imageio.*;
import java.io.IOException;
public class SwingExample extends JFrame implements MouseListener {
    public SwingExample() {
        super("This is an example");
        try {
            Image largeImage = ImageIO.read(new URL("http://today.java.net/jag/bio/JagHeadshot.jpg"));
            // ImagePanel is a JComponent subclass (see below)
            ImagePanel displayPanel = new ImagePanel(largeImage);
            // by addint a mouse listener to it, we can listen for clicks on the image
            displayPanel.addMouseListener(this);
            // content pane is the main container for the frame
            Container cp = getContentPane();
            // wraps the image panel in a scroll pane
            JScrollPane scroller = new JScrollPane(displayPanel);
            // tell the scrollbar what size you would like it to be, otherwise
            // it will try to be as large as the viewport component
            scroller.setPreferredSize(new Dimension(100, 100));
            // add the scrollpane to our frame here
            cp.add(scroller);
        catch (IOException ioe) {
            ioe.printStackTrace();
        // swing components use layout managers to help with resizing frames.
        // pack() tries to resize all components to their preferred size using
        // the layout managers. By setting the layout of a component to null,
        // you can use setBounds or setSize to explicitly tell components how
        // big they should be, but they won't automatically resize.
        pack();
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    // since we said we implement the MouseListener interface, we must include
    // all the methods. Of course, you can leave the body blank if you are not
    // interested in an event
    public void mousePressed(MouseEvent evt) {
        System.out.println("Pressed at " + evt.getX() + "," + evt.getY());
    public void mouseReleased(MouseEvent evt) {
        System.out.println("Released at " + evt.getX() + "," + evt.getY());
    public void mouseClicked(MouseEvent evt) {
        System.out.println("Clicked at " + evt.getX() + "," + evt.getY());
    public void mouseEntered(MouseEvent evt) {
        System.out.println("Entered at " + evt.getX() + "," + evt.getY());
    public void mouseExited(MouseEvent evt) {
        System.out.println("Exited at " + evt.getX() + "," + evt.getY());
    // simple overwritten component to display an image
   class ImagePanel extends JComponent {
       private Image drawImage;
       public ImagePanel(Image image) {
          setImage(image);
       public void setImage(Image image) {
          if (image == null) {
             this.drawImage = null;
             return;
          int width = image.getWidth(this);
          // if the image is not fully loaded, it's width will
          // return 0
          if (width <= 0) {
             MediaTracker tracker = new MediaTracker(this);
             tracker.addImage(image, 0);
             try {
                tracker.waitForID(0);
             catch (InterruptedException ie) {}
             width = image.getWidth(this);
          int height = image.getHeight(this);
          this.setPreferredSize(new Dimension(width, height));
          this.drawImage = image;
       // overwrite paintComponent here instead of paint
       public void paintComponent(Graphics g) {
          g.drawImage(drawImage, 0, 0, this);
    public static void main(String[] args) {
        JFrame frame = new SwingExample();
        frame.setVisible(true);
}