NullPointerException Thrown when loading images

Question

Hey folks,
I've had a look in this forum for answers to this problem but they currently don't seem to be working for me.
I've migrated my java application to be a jnlp application.
I was loading the images for two buttons in the app as follows :-
backButton.setIcon(new ImageIcon("./resources/images/back.png"));
forwardButton.setIcon(new ImageIcon("./resources/images/forward.png"));
As per the instructions I found, I located the two png files within MyApp.jar.
The location of the images in the MyApp.jar is in the folder resources/images.
I changed the code loading the images to be
backButton.setIcon(new ImageIcon(this.getClass().getClassLoader().getResource("/resources/images/back.png")));
forwardButton.setIcon(new ImageIcon(this.getClass().getClassLoader().getResource("/resources/images/forward.png")));
i.e. I took out the leading dot '.' and replaced it with '/' as from what I understand this is the only way that the class package isn't prepended to the
resource name??
I've tried that and a couple of other combinations but to no avail. Would anyone have any indication as to how to load these images?
I haven't even been able to get to the real hard parts of the debug yet ;-)
Thanks,
Mark.

Answer 1

Have you tried?
backButton.setIcon(new ImageIcon(this.getClass().getClassLoader().getResource("resources/images/back.png")));
forwardButton.setIcon(new ImageIcon(this.getClass().getClassLoader().getResource("resources/images/forward.png")));
How does the exception log look like?
Rule: No file paths. You can't use absolute or relative file paths to locate your jars holding your resources (e.g. jar:file:///c:/java/jws/.cache/resources.jar). Absolute file paths won't work because you never know where Java Web Start will put your jar on the user's machine. Relative file paths won't work because Java Web Start mangles the names of your jars (e.g. venus.jar becomes RMvenus.jar) and every JNLP client implementation has the right to mangle your names in a different way and you, therefore, can't predict the name with which your jar will be rechristend and end up on the user's machine in the application cache.
http://rachel.sourceforge.net/