getting panels the size I want without using IDE

[Colm Dickson]

Hello.


Why is it that when I add panels of a set size to a frame container of a set size, that the panels just fill the size of the panel and do not take on the dimension I give them? I want to achieve this without using the IDE please. As an example, I include some simple code below. Can anyone point out to me why the panel sizing has not affected the resulting panels

import java.awt.*;
import javax.swing.*;
import javax.swing.border.Border;

public class Main {

    public static void main(String[] args) {
 

    JFrame frame = new JFrame("panels demo")    ;
    frame.setSize(300,300);
    frame.setLayout(new GridLayout(3,1));
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panelA = new JPanel();
    JPanel panelB = new JPanel();
    panelA.setSize(150,150);
    panelB.setSize(150,150);
    panelA.setBorder(BorderFactory.createLineBorder(Color.BLACK));
    panelB.setBorder(BorderFactory.createLineBorder(Color.RED));
    Container con = frame.getContentPane();
    con.add(panelA);
    con.add(panelB);

    frame.setVisible(true);

    }

}

Thanks,

Colm

[Rob Spoor]

You're using a LayoutManager (which is a good thing), but most of those ignore the size you've set using setSize. Try setPreferredSize instead.

[Colm Dickson]

Thanks for replying.

I tried the same code but replace the setSize with setPreferredSize using a dimension instance set to the size I wanted

Dimension dim = new Dimension(150,150);
panelA.setPreferredSize(dim);

but the end result was the same. The panels still took up the same space as he main frame.

Colm.

[Maneesh Godbole]

The frame's content pane defaults to BorderLayout which does not respect the user defined sizes. Set it to FlowLayout and then try adding the panels.

[Colm Dickson]

Thanks very much...that worked, I can now see the benefit of adding panels to panels to get things looking how I want them.


Colm.

[Rob Camick]

You should also be using frame.pack() if you want the layout managers to repect the preferred size.