When I export I don't see any images

Question

My program runs fine when it’s in Eclipse however when it's exported you can’t see any of the images.

I know it’s something to do with this code:

InputStream in = new FileInputStream("res/grassFull.png");
        PNGDecoder decoder = new PNGDecoder(in);

        ByteBuffer buf = ByteBuffer.allocateDirect(4 * decoder.getWidth() * decoder.getHeight());
        decoder.decode(buf, decoder.getWidth() * 4, Format.RGBA);
        buf.flip();

But I'm not sure how to fix this, I have change the filepath or something.

I need to get the image to be read into an input stream so that I can store it as a GL texture.