Re: Simple BorderLayout problem

From:
Lew <noone@lewscanon.com>
Newsgroups:
comp.lang.java.programmer
Date:
Mon, 15 Feb 2010 12:32:39 -0500
Message-ID:
<hlc0fo$cmh$1@news.albasani.net>
Fencer wrote:

... problem with BorderLayout ...
I have JPanel with a TitledBorder (like a "group" widget) and this
JPanel contains a button.

Now I want to displays this JPanel centered horizontally and vertically
and I don't want it to occupy all the space of the client area of the
JFrame.

I tried this [indentation restored from original post - LB]:
package main;

import java.awt.BorderLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.TitledBorder;

public class CenteredGroup {

  CenteredGroup() {
    frame.setSize(1024, 768);
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel contentPane = (JPanel)frame.getContentPane();

    BorderLayout borderLayout = new BorderLayout(50, 50);

    frame.setLayout(borderLayout);

    contentPane.setLayout(borderLayout);

    JPanel groupPanel = new JPanel();

    groupPanel.setBorder(new TitledBorder("This is my group text."));

    JButton button = new JButton("A button");

    groupPanel.add(button);

    contentPane.add(groupPanel, BorderLayout.CENTER);

    frame.setVisible(true);
  }

  public static void main(String[] args) {
    new CenteredGroup();
  }

  JFrame frame = new JFrame("Centered Group");


Sorry, but the placement of this declaration and initialization in the source
is confusing

}

However, the "group control" occupies the entire client area of the
frame. Why?


RedGrittyBrick wrote:

Because that is the defined behaviour of BorderLayout. If you don't want
that behaviour it is best to not use BorderLayout.

<http://java.sun.com/javase/6/docs/api/java/awt/BorderLayout.html >

You might like to read the tutorials and try some other layout managers

<http://java.sun.com/docs/books/tutorial/uiswing/layout/visual.html>
<http://java.sun.com/docs/books/tutorial/uiswing/layout/using.html>

GridBagLayout is notoriously hard to understand. Many experienced Java
Developers feel it is worthwhile getting to know it well.

I've often seen it asserted that it is surprisingly easy to write your
own layout manager.

I'd recommend you also try a third party layout manager like MigLayout.


Side notes, OP: Do your GUI on the EDT only. Remember to 'pack()'. I suggest
doing the 'setVisible()' outside the constructor. Package-private access
isn't bad, but I wonder why you chose it over private access.

--
Lew

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