I've been trying to load up an image dynamically in runtime for the longest time and have taken a look at other posts on this site and have yet to find exactly the thing that will work. I am trying to load an image while my GUI is running (making it in runtime) and have tried various things. Right now, I have found the easiest way to create an image is to use a JLabel and add an ImageIcon to it. This has worked, but when I go to load it after the GUI is running, it fails saying there is a "NullPointerException". Here is the code I have so far:

p = Runtime.getRuntime().exec("python C:\\FaceVACS\\roc.py " + "C:/FaceVACS/OutputCMC_" + target + ".txt " + "C:/FaceVACS/ROC_" + target + ".png");
Icon graph = new ImageIcon("C:\\FaceVACS\\OutputCMC_" + target + ".png");
roc_image.setIcon(graph);
panel.add(roc_image);
panel.revalidate();
gui.frame.pack();

I tried panel.validate(), panel.revalidate(), and I've also tried gui.getRootPane(), but I can't seem to find anything that will work.

Any ideas would be helpful! Thanks