How to make a JPanel inside a JFrame fill the whole window?

Question

In the below example, how can I get the JPanel to take up all of the JFrame? I set the preferred size to 800x420 but it only actually fills 792x391.

import j         


        

Answer 1

This took me forever to figure out but its actually the simplest code ever. Just create a parent panel and pass GridLayout then add your child panel like this.

JPanel parentPanel= new JPanel(new GridLyout());
JPanel childPanel= new JPanel();
parentPanel.add(childPanel);