I have a slightly different approach that might be useful/more beneficial to some.
Under your main project folder, create a resource folder. Your folder structure should look something like this.
- Project Folder
- build
- dist
- lib
- nbproject
- resources
- src
Go to the properties of your project. You can do this by right clicking on your project in the Projects tab window and selecting Properties in the drop down menu.
Under categories on the left side, select Sources.
In Source Package Folders on the right side, add your resource folder using the Add Folder button. Once you click OK, you should see a Resources folder under your project.
You should now be able to pull resources using this line or similar approach:
MyClass.class.getResource("/main.jpg");
If you were to create a package called Images under the resources folder, you can retrieve the resource like this:
MyClass.class.getResource("/Images/main.jpg");