Loading resources with a .jar Applet

Question

I've made an simple applet which loads an image which is included in the .jar-file that I've made. The project has one package named "kap12" and one class named "U1". I have one folder included named "resrc" where my image is located. This folder is located in the root (same folder as kap12).

This is the directory structure:

test.jar
   *kap12
      -U1.class
   *resrc
      -django.jpg

test.html //outside the .jar, same folder as where test.jar is located

This program works fine when I run it in Eclipse with Appletviewer (without the .jar). It locates the image and shows it. But when I run it in html with the .jar then the program can't find it. I get nullpointer exception everytime. Here's my .html:

<HTML>
<HEAD>
</HEAD>
<TITLE> U1 </TITLE>
<BODY BGCOLOR="EEEEEE">
<CENTER>
<P ALIGN=CENTER>
<APPLET code="kap12/U1.class"
archive="test.jar"
width="1280"
height="720">
</APPLET>
</P>
</CENTER>
</BODY>
</HTML>

And here's my SSCCE:

package kap12;

import java.awt.FlowLayout;
import java.net.URL;
import javax.swing.ImageIcon;
import javax.swing.JApplet;
import javax.swing.JLabel;

public class U1 extends JApplet {

JLabel lbl0;
JLabel img0;
URL imgURL;

ImageIcon django = createImageIcon("resrc/django.jpg");

public void init() {

    setLayout(new FlowLayout());
    lbl0 = new JLabel("Test");
    img0 = new JLabel(django);      
    getContentPane().add(img0);
    getContentPane().add(lbl0);
    img0.setVisible(true);
}

/** Returns an ImageIcon, or null if the path was invalid. */
protected static ImageIcon createImageIcon(String path) {
    java.net.URL imgURL = U1.class.getClassLoader().getResource(path);
    if (imgURL != null) {
        System.out.println(""+imgURL);
        return new ImageIcon(imgURL);
    } else {
        System.err.println("Couldn't find file: " + path);
        return null;
    }
}
}

I've tested using getClass() and getClass().getClassLoader(). I've tested writing "/resrc/django.jpg" in the String path. I've tested with and without .jar. I've tested adding the resrc-folder into the kap12 package folder. It seems that I've tested everything. I've spent days trying to get this to work.

What should I write? I've read a lot of threads about this here on StackOverflow but no success. Thanks.

Update: I've tested everything you've written Andrew but it can't find it anyway.

This is what I've got from the -tvf:

C:\Program\Java\jdk1.7.0_40\bin>jar -tvf D:\Path\test.jar 25 Mon Jan 20 14:48:14 CET 2014 META-INF/MANIFEST.MF 2035 Mon Jan 20 14:48:04 CET 2014 pkg/U1.class 496057 Sun Feb 03 15:25:06 CET 2013 resrc/django.jpg

Which is the exact problematic method that throws NPE? Would you post the stacktrace? — Martín Schonaker, Jan 16 '14 at 13:49
Don't know how to see the stacktrace when it's in a web browser. — Kalekulan, Jan 16 '14 at 14:41

Andrew Thompson · Answer 1 · 2014-01-16T16:10:41.773

ImageIcon django = createImageIcon("resrc/django.jpg");

Should be:

ImageIcon django = createImageIcon("/resrc/django.jpg");

Update

Don't know exactly how to do just that but I killed "Java SE" from Task Manager, then I deleted the old .jar-file. I have a JOptionPane.showMessageDialog which says what "String path" contains and it seems to update fine.

OK, the 'updates fine' is the important part. Do that same thing for each test.

Just noticed the finer details of the loading method:

protected static ImageIcon createImageIcon(String path) {
    java.net.URL imgURL = U1.class.getClassLoader().getResource(path);

Safer would be:

protected ImageIcon createImageIcon(String path) {
    java.net.URL imgURL = this.getClass().getResource(path);

I know the string I specified works for the 'context class loader', but that cannot be called from a static method.

If that still fails, go to the command line (e.g. the Windows command prompt or Linux/Unix Console, and provide the output of:

> jar -tvf path/to/the/test.jar

I've tested: ImageIcon django = createImageIcon("/resrc/django.jpg"); ImageIcon django = createImageIcon("resrc/django.jpg"); With both getResource() and getClassLoader().getResource(). It can't find the image. — Kalekulan, Jan 16 '14 at 14:42
Don't know exactly how to do just that but I killed "Java SE" from Task Manager, then I deleted the old .jar-file. I have a JOptionPane.showMessageDialog which says what "String path" contains and it seems to update fine. — Kalekulan, Jan 16 '14 at 15:05

Loading resources with a .jar Applet

1 Answers1

Update