How to load an image to display

Hi there,
I would like to write a piece of code to load an image and display without using applet. Is that possible? Thanks.

John

Lots of options when it comes to loading and displaying images. Here's an easy one. The image is located in the imagesfolder which is located in the same folder as the DisplayAnImage class file.

Thank you very much. I provided a very detailed answer. One more thing, I don't have the tiff file yet. Can it handle tiff file in similar manner jpeg? Thanks again

John
I forgot one detail in your response.
My image file is a large image like a graphic document. You used ImageIcon hold the image. Would that be O.K.?
[ August 05, 2004: Message edited by: John McDonald ]

I have another question based on that. If we were using strictly AWT what would we do in this case?

Here's a link to an earlier post Supported image formats from this forum that may be helpful for the tiff question. For the image size in the JLabel(ImageIcon) I would try and see if it works.

And here's a demo of how to diaplay an image in the AWT.

import java.awt.*;
import java.awt.event.*;
 
public class AWTImageDisplay
{
    public static void main(String[] args)
    {
        AWTImageDisplayPanel imagePanel = new AWTImageDisplayPanel();
        ScrollPane scrollPane = new ScrollPane();
        scrollPane.add(imagePanel);
        Frame f = new Frame();
        f.addWindowListener(new WindowAdapter()
        {
            public void windowClosing(WindowEvent e)
            {
                System.exit(0);
            }
        });
        f.add(scrollPane);
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}
 
class AWTImageDisplayPanel extends Panel
{
    Image image;
 
    public AWTImageDisplayPanel()
    {
        loadImage();
        setBackground(Color.black);
    }
 
    public void paint(Graphics g)
    {
        super.paint(g);
        int w = getWidth();
        int h = getHeight();
        int imageWidth = image.getWidth(this);
        int imageHeight = image.getHeight(this);
        int x = (w - imageWidth)/2;
        int y = (h - imageHeight)/2;
        g.drawImage(image, x, y, this);
    }
 
    /**
     * Let clients know our size requirements
     */
    public Dimension getPreferredSize()
    {
        return new Dimension(image.getWidth(this), image.getHeight(this));
    }
 
    private void loadImage()
    {
        String fileName = "images/cougar.jpg";
        Toolkit toolkit = Toolkit.getDefaultToolkit();
        MediaTracker tracker = new MediaTracker(this);
        image = toolkit.createImage(fileName);
        tracker.addImage(image, 0);
        try
        {
            tracker.waitForID(0);
        }
        catch(InterruptedException ie)
        {
            System.out.println("interrupt: " + ie.getMessage());
        }
    }
}

[ August 07, 2004: Message edited by: Craig Wood ]

Hello,
I am back. I would like to ask how do make sure the image loaded sucessfully in case jpg file does not exist or it is corrupted. Any hint is greatly appreciated. Thanks.

John

The loadImage method below should let you know if there is trouble. ImageIO is new in j2se 1.4 and offers other ways to get to the image data, eg, via the File api (see read methods in ImageIO api).

The ImageIcon (j2se 1.2+) class doesn't seem to give any notice of trouble. One way to peek under the covers relies on the fact that the Component class implements the ImageObserver interface which has the single method imageUpdate. So if you load the image inside a Component you can override the imageUpdate method and use it to monitor the image loading process and/or check the result.

In the AWT you can either use the ImageObserver interface as above or work directly with methods in the MediaTracker class to monitor the image loading process.

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.net.*;
import javax.imageio.ImageIO;
import javax.swing.*;
 
public class ImageLoading
{
    public ImageLoading()
    {
        BufferedImage image = loadImage();
        JLabel label = new JLabel(new ImageIcon(image));
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(new JScrollPane(label));
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
    }
 
    private BufferedImage loadImage()
    {
        BufferedImage image = null;
        String fileName = "images/greathornedowl.jpg";
        try
        {
            URL url = getClass().getResource(fileName);
            image = ImageIO.read(url);
        }
        catch(MalformedURLException mue)
        {
            System.err.println("url: " + mue.getMessage());
        }
        catch(IllegalArgumentException iae)
        {
            System.err.println("arg: " + iae.getMessage());
        }
        catch(IOException ioe)
        {
            System.err.println("read: " + ioe.getMessage());
        }
        if(image == null)
        {
            image = new BufferedImage(10, 10, BufferedImage.TYPE_INT_RGB);
            System.out.println("unable to load image, returning default");
        }
        return image;
    }
 
    public static void main(String[] args)
    {
        new ImageLoading();
    }
}

Hi Craig,
Thanks again for continuing answering my question. It works fine for the local images. But I have a images file from other location, it can't get the source and throw the exception, of course, eventhough I define an absolute path.

John

getResource works for files on the classpath, including files inside jar files for j2se 1.4+. For network URLs you could try constructing a URL from the absolute path.