java jar getResource() null exception

    1. Adding resource folder to classpath:

    When you Clean-&-Build a NetBeans Ant Based Project it creates a manifest.mf file in the root directory of the project. This file gets included in the JAR file also. Modify this file and add entry like follows:

    Manifest-Version: 1.0
    X-COMMENT: Main-Class will be added automatically by build
    Class-Path: arts/ 

    slash is important after arts in the class path.

    Including the arts resource folder in the distribution

    Either copy this folder in the dist folder after the build or add a ANT target to copy the required resources in the dist folder.

    2. Add the target like as follows in the build.xml file:

    <target name="-post-jar">
         <mkdir dir="${dist.dir}/resources"/>
         <copy todir="${dist.dir}/resources">
             <fileset dir="${basedir}/resources" />
         </copy>
     </target>

    3. Code to access such resources:

    The code needed to access such resource files shall be as follows: (This will not work in design time but surely from the JAR file)

    // pay attention to relative path
    URL resource = ClassLoader.getSystemResource("gui/refresh.png");
    ImageIcon tmp = new ImageIcon(resource);

    NOTE: The files manifest.mf and build.xml located in the root directory of the project are accessible from the Files Panel in NetBeans IDE