如何基于JComboBox选择更改JTextField

This is just a silly program I am working on for school but I am having some trouble. I have a JComboBox and based on what the user selects I want to change the text field. I'm having some trouble with that however, as it stands now the program compiles and runs but the text field doesn't change. I've found plenty of examples of people doing far more complicated things but I just need a simple solution. Here is the code. Thanks!This is just a silly program I am working on fo