textfield value for JSlider

[Candy Bortniker]

I am trying to get my JSlider to accept a value enter in a textfield and move the slider accordingly. I got some help from the API but it's not working. Any advice would be helpful.

 
class BlueSliderBeanFrame extends JFrame
{
  public static final int DEFAULT_WIDTH = 350;
  public static final int DEFAULT_HEIGHT = 100;
  JSlider slider = new JSlider(0,255);
  private JPanel sliderPanel;
  private JLabel integerlbl;
  private JTextField textfield;
  private ChangeListener listener;
  public BlueSliderBeanFrame()
  {
    setTitle("BlueSliderBean");
    setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
    sliderPanel = new JPanel();
    sliderPanel.setLayout(new FlowLayout(FlowLayout.LEFT));
    //listens for slider
    listener = new ChangeListener()
    {
public void stateChanged(ChangeEvent event)
{
   //update text field when the slider value changes
   JSlider source = (JSlider)event.getSource();
   if (source.getValueIsAdjusting())
   {
      int fps = (int)source.getValue();
   }
   integerlbl.setText("" + source.getValue());
}
     };

     textfield.addPropertyChangeListener(this);

     //add a filled slider
     slider.setPaintTicks(true);
     slider.setMajorTickSpacing(20);
     slider.setMinorTickSpacing(5);
     slider.putClientProperty("JSlider.isFilled", Boolean.TRUE);
     addSlider(slider, "Filled");
     //add the text field that displays the slider value
     integerlbl = new JLabel();
     Container contentPane = getContentPane();
     contentPane.add(sliderPanel, BorderLayout.CENTER);
     contentPane.add(integerlbl, BorderLayout.SOUTH);
  }//close constructor
  public void propertyChange(PropertyChangeEvent e)
  {
    if (textfield.equals(e.getPropertyName()))
    {
Number value = (Number)e.getNewValue();
if (slider != null && value != null)
{
  slider.setValue(value.intValue());
}
     }
  }

  public void addSlider(JSlider s, String description)
  {
     s.addChangeListener(listener);
     JPanel panel = new JPanel();
     panel.add(s);
     panel.add(new JLabel(description));
     sliderPanel.add(panel);
  }
}//close SliderBeanFrame

 

[kyle amburn]

Hi-
I have a couple of observations.
1.) Since you are adding this as a PropertyChangeListener, I assume that you have implemented PropertyChangeListener for the class.
2.)In your propertyChangedEvent method you are testing the equality of a JTextField and a String (PropertyChangeEvent.getPropertyName() returns a String). These two will never equal.
3.)You would be better suited using a DocumentListener to listen for changes to the JTextField to update the JSlider. You do this using JTextField.getDocument().addDocumentListener(listener).
Kyle

[Candy Bortniker]

I haven't used that statement before and what I have tried doesn't seem to work as I get numerous compile errors. Here's how I have it now:

 
public void propertyChange(PropertyChangeEvent e)
{
//if (textField.equals(e.getPropertyName()))
//{
   //Number value = (Number)e.getNewValue();
//if (slider != null && value != null)
//{
Number value = JTextField.getDocument().addDocumentListener(listener);
slider.setValue(value.intValue());
//}
//}
}
 

Does JTextField.getDocument().addDocumentListener(listener);
give me the value of textfield?

[kyle amburn]

Hi-
getDocument().addDocumentListener(DocumentListener) return void so you cannot caset it to a Number object. What you need to do is instead of implementing PropertyChangeListener and using the propertyChange(PropertyChangeEvent), you chould implement DocumentListener and use its three methods:
1. changedUpdate(Document Event)//just use a null implementation of this
2. insertUpdate(DocumentEvent)
3. removeUpdate(DocumentEvent)
Each time the value in the JTextField is changed then the insertUpdate and/or removeUpdate method will be called.

 
public void changeUpdate(DocumentEvent e){}
public void insertUpdate(DocumentEvent e){
    updateSlider();
}
public void removeUpdate(DocumentEvent e{
    updateSlider();
}
private void updateSlider(){
      int val = 0;
      try{
          val = Integer.parseInt(textField.getText());
      }catch (numberFormatException e) {
          //fix if you wish
      }
      slider.setValue(val);
}

[Candy Bortniker]

How would I then activate this code? I would think that I need textField.<something> but I have tried everything I can find and nothing has worked so far.

[kyle amburn]

You use

textField.getDocument().addDocumentListener(this);

This will then force the JTextField to "notify" your Class each time the value in the JTextField is changed.
Kyle
[ October 23, 2003: Message edited by: kyle amburn ]

[Candy Bortniker]

Here is the compile error that I get on that statement:
addDocumentListener(javax.swing.event.DocumentListener) in javax.swing.text.Document cannot be applied to (BlueSliderBeanFrame)
textField.getDocument().addDocumentListener(this);
^

[kyle amburn]

Hi-
Did you implement DocumentListener for the
BlueSliderBeanFrame? The error you got is saying that the object you added (this) is not an instance of a DocumentListener. Your class declaration needs to say the following:

  
class BuleSliderBeanFrame extends JFrame implements DocumentListener{
//...
} 

Kyle

[Candy Bortniker]

Thank you so much!! My bean is working!!