Re: how to set (preferred) JSlider length?

Knute Johnson <>
Fri, 08 Aug 2008 08:53:45 -0700
Mark_Galeck wrote:

On Aug 7, 6:23 pm, Knute Johnson <>

Mark_Galeck wrote:

Nope, same thing as always, slider length is 1024 (covers the whole

Change the layout manager to something that honors preferred size.

My preference is GridBagLayout.

same problem, does not honor, heres the code , width is 200
not 400

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

public class foo extends JApplet {
    public void init() {
        GridBagConstraints gridBagConstraints;

        setLayout(new GridBagLayout());

        gridBagConstraints = new GridBagConstraints();
        gridBagConstraints.gridx = 0;
        gridBagConstraints.gridy = 0;
        gridBagConstraints.weightx = 1.0;
        add(new JPanel(), gridBagConstraints);

        gridBagConstraints = new GridBagConstraints();
        gridBagConstraints.gridx = 1;
        gridBagConstraints.gridy = 0;
        gridBagConstraints.fill = java.awt.GridBagConstraints.HORIZONTAL;
        JSlider s = new JSlider(0, 400);
        add(s, gridBagConstraints);
        Dimension d = s.getSize();
        d.width = 400;

For some reason I'm having trouble reading your posts so I'll post a
reply to this one. See the code below for an example on how to create
your JSlider. Also, note that any time Swing GUI components are
accessed (and in particular created) it must be done on the event
dispatch thread (EDT). Your code in the init() method needs to be
called on the EDT just as the 'new test9()' below in my code is called.

BorderLayout will pay no attention to preferred sizes unless you pack
your container. But as soon as you resize the container, BorderLayout
changes the size of your components. GridbagLayout, unless you
specifically tell it to, won't. GBL doesn't honor maximum size though.

In my example below I set the minimum size too. If you make the frame
even a tiny bit smaller, GBL will resize the JSlider to minimum size.
No matter how big you make the frame though, it will stay preferred size.

One other note, the Dimension objects that you pass to the set?Size()
methods have to be different objects. You can't just reuse the same one
and change the width or height, as any changes will be made to the
original object and your sizes will be off. This is why I created a new
Dimension object for the minimum size.

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

public class test9 extends JFrame {
     public test9() {

         setLayout(new GridBagLayout());
         GridBagConstraints c = new GridBagConstraints();

         JSlider s = new JSlider(0,400);
         Dimension d = s.getPreferredSize();
         d.width = 400;
         s.setMinimumSize(new Dimension(200,d.height));



     public static void main(String[] args) {
         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 new test9();


Knute Johnson
email s/nospam/knute2008/

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