JButtons inside JPanels with a GridLayout JFrame

Question

I have one JFrame that is set to a GridLayout of size NxN. N is given by the user as a command line at the start of the program. JButtons in an NxN pattern are added to the

Answer 1

Does each JButton need its own JPanel to use GridLayout?

No. Add and setLayout on JFrame don't do what they appear to. JFrame is Top-Level Containers and it is better to organise your content in JPanels.

You should organize your panels in that form:

----JPanel----------------------------|
| ---LeftPanel---  ---ButtonsPanel--- |
| |             |  |                | |
| |             |  |                | |
| |             |  | GridLayout(N,N)| |
| |             |  |                | |
| |             |  |                | |
| ---------------  ------------------ |
---------------------------------------

Then add JPanel to the JFrame. Also put panels in seperate classes:

class BPanel extends JPanel {
    public BPanel() {
        GridLayout layout = new GridLayout(N,N, hgap, vgap);
        setLayout(layout);
        for (int row = 0; row < N; row++){
            for (int col = 0; col < N; col++){
                JButton b = new JButton ("("+row+","+col+")");
                add(b).setLocation(row, col);
                b.addActionListener(new ButtonEvent(b, system, row, col));
            }
        }
    }
}
class LeftPanel extends JPanel {
....
}

class MainFrame extends JFrame {
    public MainFrame() {
        JPanel p = new JPanel();
        p.add(new LeftPanel());
        p.add(newButtonsPanel());
        add(p);
    }
}