Name: tb29552 Date: 06/29/98


/*
 * Here is a simple application that has a JSlider
 * and 2 JButtons. One button changes the slider
 * value. The other changes the slider model
 *
 * When the app is first started, clicking on the
 * "Value" JButton will advance the slider.
 *
 * After the "Change model" button is clicked,
 * the "Value" button continues to call setValue()
 * but the slider does not move.
 */
/*
 * The cause is the fact that the L&F class is not a
 * PropertyChangeListener of the JComponent. When
 * setModel changes the model, the references
 * held by the L&F delegate become invalid. The L&F
 * delegates do not change their modelListeners to
 * the new model.
 *
 * Changing the L&F delegate to be a listener of the
 * JComponent instead of the model will also kill
 * this bug.
 */

import com.sun.java.swing.*;
import java.awt.event.*;

public class SetModelBug extends JFrame {
  public static void main( String arg[] ) {
    SetModelBug b = new SetModelBug();
    b.setSize( 300, 50 );
    b.show();
  }

  protected SetModelBug() {
    slider = new JSlider(); // Uses default model

    // Construct the model change button
    modelChangeButton = new JButton("Change model");
    modelChangeButton.addActionListener( new ActionListener() {
      public void actionPerformed( ActionEvent event ) {
        if ( newModel == null ) {
          newModel = new CustomBoundedRangeModel();
          slider.setModel( newModel );
        }
      }
    });

    // Construct the value change button
    valueChangeButton = new JButton("Value");
    valueChangeButton.addActionListener( new ActionListener() {
      public void actionPerformed( ActionEvent event ) {
        int newValue = slider.getValue() + 10;
        if ( newValue > slider.getMaximum() )
          newValue = slider.getMinimum();
        slider.setValue( newValue );
System.out.println("In \"Value\" JButton: setValue to: " +
newValue);
      }
    });

    // Add components
    rootPane.getContentPane().add( slider, "Center" );
    rootPane.getContentPane().add( modelChangeButton, "West" );
    rootPane.getContentPane().add( valueChangeButton, "East" );
  }

  private JSlider slider;
  private JButton modelChangeButton;
  private JButton valueChangeButton;
  private CustomBoundedRangeModel newModel;
}

/**
   Custom model that fixes the extent to 0
*/
class CustomBoundedRangeModel extends DefaultBoundedRangeModel {
  public void setRangeProperties(
                                 int newValue,
                                 int newExtent,
                                 int newMin,
                                 int newMax,
                                 boolean adjusting) {
    super.setRangeProperties( newValue, 0, newMin, newMax, adjusting );
  }
}

(Review ID: 34448)
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