“Exception in thread ”AWT-EventQueue-0“ java.lang.NullPointerException”. I have no clue what I'm doing wrong

Question

I am making a calculator for an AP Computer Science Final. I built the GUI in Eclipse using Jigloo, and I quickly tried to learn about Action Listeners so you can hit the button

Answer 1

You button variables aren't assigned until you call initGUI(), which is at the bottom of your constructor. So, when you do this:

jButton3.addActionListener(new ListenToOne());

... Java sees this:

null.addActionListener(new ListenToOne());

... which is obviously a problem.