How can I display a bitmap image in a Java applet?

Question

I am having a hard time figuring out how to show an Image (or ImageIcon) in a Java applet. The following is my code. The picture (test.bmp) does exist and is on the D drive but when I run this I get the applet window with nothing in it. Can somebody tell me what I am missing to make the ImageIcon show?

public class Form1 extends JApplet {
    ImageIcon i;

    public void init(){
        i = new ImageIcon("D:\test.bmp");
    }

    public void paint(Graphics g){
        i.paintIcon(this, g, 0, 0);
    }
}

Thanks, Steve.

Answer 1

Referencing your image through an absolute local file path might not work when you run your applet from a server. Use the ImageIcon (URL location) constructor and Have the URL point to the image resource on the server. Use the JApplet.getCodeBase() to determine where your applet originates and append the file name to it.

public class Form1 extends JApplet {
    Image i;

    public void init() {
        try {
            i = ImageIO.read(new URL(getCodeBase(), "test.bmp"));
        } catch (MalformedURLException ex) {
            ex.printStackTrace();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

    public void paint(Graphics g) {
        g.drawImage(i, 0, 0, null);
    }
}

Edit: ImageIO supports BMP and the changed sample works for me.

Edit 2: If it still doesn't display the image, try "../test.bmp" because when you run an applet from lets say Eclipse it has the bin directory as the codebase.

Edit 3: If you put your test.bmp into the jar or on the classpath, you can load it using the same way but replacing

new URL(getCodeBase(), "test.bmp")

with

Form1.class.getResource("test.bmp")

Answer 2

To start with, it's probably a good idea to correctly escape your \ as \\.

Edited to add: You probably want to learn your language's (or library's) equivalent of Path.combine (or File.join) which is a method for taking a list of file path parts and combining them with the platform-appropriate path separator. Or you can write it yourself quickly in Java, as the path separator is documented in File.pathSeparator.

(Off the top of my head, I didn't know that forward slash always works in ImageIcon, but note the other response that indicates this).

Additionally, make sure you are loading a supported file type, such as .png, .gif or .jpg. BMP may be supported in JDK 1.5

Also, if you are running in an Applet context, you may not have access to the path in question due to sandboxing rules. In that case, make it available in the same path as to the HTML file hosting the applet (possibly in the Jar's path, if memory serves me), and use a relative path.