java - How to correctly get image from 'Resources' folder in NetBeans

Question

I have a Java Project in NetBeans 7.0.

I want to add some image to some label dynamically. The image will differ depending on the state of the program.

I put one such image, 'filling.jpg', in the 'resources' folder of my project.

I want to reach this file correctly (not by absolute or relative path, because that will cause problems when I build the jar file).

So I found this method:

ImageIcon fillingIcon = new ImageIcon(getClass().getClassLoader().getResource("filling.jpg"));
labelFontFilling.setIcon(fillingIcon);

It keeps give me java.lang.NullPointerException. But I am sure that there is that image, because I can assign the image to the label from the NetBeans Properties menu for that label (but I don't want this, I want to add the image by Java code).

What am I doing wrong, and how can I get that image correctly?

Answer 1

This was a pain, using netBeans IDE 7.2.

1. You need to remember that Netbeans cleans up the Build folder whenever you rebuild, so

2. Add a resource folder to the src folder:

   • (project)
     • src
       • project package folder (contains .java files)
       • resources (whatever name you want)
       • images (optional subfolders)

3. After the clean/build this structure is propogated into the Build folder:
   

   • (project)
     
     • build
       
       • classes
         
         • project package folder (contains generated .class files)
           
         • resources (your resources)
           
         • images (your optional subfolders)
           

To access the resources:

dlabel = new JLabel(new ImageIcon(getClass().getClassLoader().getResource("resources/images/logo.png")));

and:

if (common.readFile(getClass().getResourceAsStream("/resources/allwise.ini"), buf).equals("OK")) {

worked for me. Note that in one case there is a leading "/" and in the other there isn't. So the root of the path to the resources is the "classes" folder within the build folder.

Double click on the executable jar file in the dist folder. The path to the resources still works.