In my project I have 2 packages. images - contain images and notification - contain java files
In notification/main.java I get Image o
i've also been on this and it turns out that you need to create a package inside of your src folder. for instace if you create a package called images inside of the src folder, your relative path will be /images/yourimage.png.
Notice that the slash(/) must be there! more info here http://forums.macrumors.com/showthread.php?t=533922
it worked for me