How to “do something” on Swing component resizing?

Question

I\'ve a class which extends JPanel. I overwrote protected void paintComponent(Graphics g).

There is a variable which has to be recalculate

Answer 1

It resizes automatically if it's

1. inside a BorderLayout panel and
2. put there as BorderLayout.CENTER component.

If it doesn't work, you probably have forgotten one of these two.