MyCatImage

MyCatImage.java

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

/**
This class demonstrates how to use an ImageIcon
and a JLabel to display an image.
*/

public class MyCatImage extends JFrame
{
   private JPanel imagePanel; // To hold the label
   private JPanel buttonPanel; // To hold a button
   private JLabel imageLabel; // To show an image
   private JButton button; // To get an image


   /**
Constructor
*/

   public MyCatImage()
   {
      // Set the title.
      setTitle("My Cat");

      // Specify an action for the close button.
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

      // Create a BorderLayout manager.
      setLayout(new BorderLayout());

      // Build the panels.
      buildImagePanel();
      buildButtonPanel();

      // Add the panels to the content pane.
      add(imagePanel, BorderLayout.CENTER);
      add(buttonPanel, BorderLayout.SOUTH);

      // Pack and display the window.
      pack();
      setVisible(true);
   }

   /**
The buildImagePanel method adds a label to a panel.
*/

   private void buildImagePanel()
   {
      // Create a panel.
      imagePanel = new JPanel();

      // Create a label.
      imageLabel = new JLabel("Click the button to " +
                              "see an image of my cat.");
      
      // Add the label to the panel.
      imagePanel.add(imageLabel);
   }

   /**
The buildButtonPanel method adds a button
to a panel.
*/

   private void buildButtonPanel()
   {
      ImageIcon smileyImage;

      // Create a panel.
      buttonPanel = new JPanel();

      // Get the smiley face image.
      smileyImage = new ImageIcon("Smiley.gif");

      // Create a button.
      button = new JButton("Get Image");
      button.setIcon(smileyImage);

      // Register an action listener with the button.
      button.addActionListener(new ButtonListener());

      // Add the button to the panel.
      buttonPanel.add(button);
   }

   /**
Private inner class that handles the event when
the user clicks the button.
*/

   private class ButtonListener implements ActionListener
   {
      public void actionPerformed(ActionEvent e)
      {
         // Read the image file into an ImageIcon object.
         ImageIcon catImage = new ImageIcon("Cat.jpg");

         // Display the image in the label.
         imageLabel.setIcon(catImage);

         // Remove the text from the label.
         imageLabel.setText(null);

         // Pack the frame again to accomodate the
         // new size of the label.
         pack();
      }
   }
   
   /**
The main method creates an instance of the
MyCatImage class which causes it to display
its window.
*/
   public static void main(String[] args)
   {
      new MyCatImage();
   }
}