Re: Setting extent in JSlider model

Knute Johnson <>
Tue, 07 Feb 2012 10:24:36 -0800
On 2/3/2012 12:35 PM, Fred wrote:

How can I set how much a slider will change when the user hits the
PageUp of PageDown key, and when the user clicks in the slider's

The javadoc for JSlider's model (BoundedRangeModel) setExtent() method

   When used with a slider, the extent determines how much the value
can "jump", for
   example when the user presses PgUp or PgDn.

However, setExtent() seems to have no effect. When I use the PgUp or
PgDn key, the value always changes 10% of the range regardless of the
value I request for extent.

As for clicking in the trough, metal L&F always seems to increment (or
decrement) the value by one, and for Nimbus it is the same as PgUp/

It can be very annoying when the L&F prevents a change to a value that
has a setter method. You might look to see if you can find a UI
property that could change that. The problem is that I've found even if
there is a UI property the methods in the L&F may not honor them. I
extended a menu item class to be able to do that but it may or may not
work in the future. I just figured it was a quick fix for the moment
and if it didn't work in the future I could take it out.

This program will list all the UIDefaults:

import java.util.Enumeration;

import javax.swing.UIDefaults;
import javax.swing.UIManager;

public class ListUIProperties {
   public static void main(String args[]) throws Exception {
     UIManager.LookAndFeelInfo looks[] =

     for (UIManager.LookAndFeelInfo info : looks) {

       UIDefaults defaults = UIManager.getDefaults();
       Enumeration newKeys = defaults.keys();

       while (newKeys.hasMoreElements()) {
         Object obj = newKeys.nextElement();
         System.out.printf("%50s : %s\n", obj, UIManager.get(obj));


Knute Johnson

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