Can I exit from paintComponent? ...or... how can I check for invalid data?

Question

I'm writing a calendar applet for a programming class and I've nearly completed it but I'm stuck at checking for valid data.
What seems to be happening is that paintComponent() is being called before actionPerformed.
In actionPerformed (when they click the button), it checks to make sure they entered a valid month (1 to 12). If the didn't it dispalys a message, but if they did it calls repaint().
But even if repaint() isn't called, Java still seems to call it before actionPerformed and I get exceptions.
So I tried checking inside of paintComponent() by using a simple if(...) return; but that doesn't seem to do anything... it just keeps going through with the method.
So -- Once the user presses my button I want to make sure the data is valid before repainting the screen. How can I do this?

Answer 1

I validate it in actionPerformed which is called by
the action listener... that is what you meant right?
The problem is that it seems paintComponent() is being
called before I can validate the data with
actionPerformed(). I need to stop paintComponent()
from always being calledMVC. (Model, View, Controller)
Initially the internal value of the data (the model) should be valid (or null with a check in the paintComponent method)
paintComponent (the view part) shows the state of the valid data.
You press the button.
actionPerformed is called (the controller).
It checks the value and, if valid, writes it to the data (model), then updates the view.
At no point will the view have to render invalid data, because the model is only updated after actionPerformed checks the value.
The pattern may be applied with different classes performing the three roles, or different methods in the same class (sometimes it's easier that way for simple cases).
Pete