Re: A JLabel's Size

On Mar 7, 11:45 am, Knute Johnson <nos...@xxxxxxxxxxxxxxxxxxxxxxx>
wrote:
Jason Cavett wrote:
Something I'm curious about...

When I create a JLabel and place it into a JPanel/JDialog/some other
component, it always appears as the correct size (just large enough to
display the text + appropriate boundary around the text). But, when I
attempt to get that JLabel's size, it returns 0 width and 0 height
unless I specifically set the size of the JLabel.

Shouldn't the size have been set correctly upon the addition of the
text to the label? I'm confused on how this is working and why it's
working that way.

The component has to be realized first. It gets realized when the
container it is in is either packed or its size is set.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class test8 {
public static void main(String[] args) {
Runnable r = new Runnable() {
public void run() {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

JLabel l = new JLabel("Hello World!");
f.add(l,BorderLayout.CENTER);
System.out.println(l.getWidth());

f.pack();
System.out.println(l.getWidth());
f.setVisible(true);
}
};
EventQueue.invokeLater(r);
}

}

--

Knute Johnson
email s/nospam/knute/

Okay, that makes sense.

But...why is "preferred size" recognized. For example, I can do
something like this...

JLabel label = new JLabel("Hello World");
label.setSize(label.getPreferredSize());

I never set the preferred size on my own. Is something being done
underneath the covers with preferred size?

.