CODEWITHSUNDEEP
javaswingevent-handlingjsliderchangelistener
helpdesk
helpdesk

Reputation: 2074

How to add a changeHandler() to my program

Please, I tried to add a changeHandler event but I don't think I got it right. I am looking at the following statements..

pickNum.addChangeListener(new ChangeHandler());

 @Override
 public void stateChanged(changeEvent e)
 {
   JSlider s = (JSlider)e.getSource();
   index = s.getValue();
 }

Is there something I could have done better because because, it's not working..

import javax.swing.*;

public class Slider extends JFrame{

public static int index;
JSlider pickNum = new JSlider(JSlider.HORIZONTAL,0,30,5);
public Slider()
{
 super("Slider");
 this.pack();
 this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

 pickNum.setMajorTickSpacing(10);
 pickNum.setMinorTickSpacing(1);
 pickNum.setPaintTicks(true);
 pickNum.setPaintLabels(true);
 pickNum.addChangeListener(new ChangeHandler());

 @Override
 public void stateChanged(changeEvent e)
 {
   JSlider s = (JSlider)e.getSource();
   index = s.getValue();
 }

 getPointedValue();
 this.add(pickNum);
 this.setVisible(true);

}

public final int getPointedValue()
{
    int value;
    value = pickNum.getValue();
    return value;
}


     public static void main(String[] args) {

    Slider frame = new Slider();
    System.out.println("value is :"+Slider.index);
   }

 }

[/CODE]

Upvotes: 0

Views: 1727

Answers (3)

Robin
Robin

Reputation: 36601

What is that ChangeHandler class you are talking about ? It is not part of the JDK. Did you mix up the ChangeHandler class from GWT with the ChangeListener from the JDK ?

Further, I would suggest you take a look at the Swing slider for sample code working with sliders. For example a nice sample implementation of such a ChangeListener attached to the slider

public void stateChanged(ChangeEvent e) {
    JSlider source = (JSlider)e.getSource();
    if (!source.getValueIsAdjusting()) {
        int fps = (int)source.getValue();
        if (fps == 0) {
            if (!frozen) stopAnimation();
        } else {
            delay = 1000 / fps;
            timer.setDelay(delay);
            timer.setInitialDelay(delay * 10);
            if (frozen) startAnimation();
        }
    }
}

Note the getValueIsAdjusting() call which you misses in your code snippet

Upvotes: 2

ControlAltDel
ControlAltDel

Reputation: 35011

What is your ChangeHandler? You haven't posted that code

Here is an example of using a change listener


JSlider s = new JSlider();
s.addChangeListener(new ChangeListener() {
   public void stateChanged(ChangeEvent e) {
      System.out.println("Changed: " + e);
   }
});

Upvotes: 3

Joost
Joost

Reputation: 3209

What is the implementation of your ChangeHandler? You don't really need an separate file for it, the ChangeListener interface only has one method so you can quickly provide an implementation while declaring it inline

pickNum.addChangeListener(new ChangeListener() {    
    @Override
    public void stateChanged(ChangeEvent arg0) {
        JSlider s = (JSlider) arg0.getSource();
        index = s.getValue();   
    }
});

Upvotes: 2

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