Name: el35337 Date: 06/18/98


This JavaBean used to work fine with JDK-1.1.5 and swing-1.0.1.
Now I use JDK-1.1.6 and swing-1.0.2 and I get the following message
when I try to get the TipText with the mouse:

Exception occurred during event dispatching:
java.lang.NullPointerException
        at
com.sun.java.swing.ToolTipManager$JPanelPopup.show(ToolTipManager.java:449)
        at
com.sun.java.swing.ToolTipManager.showTipWindow(ToolTipManager.java:169)
        at
com.sun.java.swing.ToolTipManager.mouseEntered(ToolTipManager.java:243)
        at
java.awt.AWTEventMulticaster.mouseEntered(AWTEventMulticaster.java:246)
        at java.awt.Component.processMouseEvent(Component.java:2293)
        at java.awt.Component.processEvent(Component.java:2129)
        at java.awt.Container.processEvent(Container.java:894)
        at java.awt.Component.dispatchEventImpl(Component.java:1764)
        at java.awt.Container.dispatchEventImpl(Container.java:939)
        at java.awt.Component.dispatchEvent(Component.java:1704)
        at
java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:1548)
        at java.awt.LightweightDispatcher.setMouseTarget(Container.java:1515)
        at
java.awt.LightweightDispatcher.processMouseEvent(Container.java:1479)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:1392)
        at java.awt.Container.dispatchEventImpl(Container.java:926)
        at java.awt.Component.dispatchEvent(Component.java:1704)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:63)

-------------
The commands:

javac Options.java
jar -cvf Options.jar Meta-inf/Manifest.mf Options.class
Options\$InnerAbstractAction.class

------------
The content of the manifest file:

Name: Options.class
Java-Bean: True

Name: Options$InnerAbstractAction.class
Java-Bean: False

------------

/**
 *
 * Options.java
 *
 */

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import java.beans.*;
//import java.awt.swing.*;
//import java.awt.swing.event.*;
import com.sun.java.swing.*;
import com.sun.java.swing.event.*;

public class Options extends JPanel {

  private Insets insets = new Insets(5,5,5,5);
  protected PropertyChangeSupport changes = new PropertyChangeSupport(this);
  protected EventListenerList changeListeners = new EventListenerList();
  private ButtonGroup rbg = new ButtonGroup();
  private String currentSelection = new String("");
  
  

  /**
   * The default constructor
   */
  public Options() {

    JRadioButton radioButton;

    // Give it a border so it stands out
    // By default, panels have no border
    setInsets(5,5,5,5);
    setBorder (BorderFactory.createEtchedBorder());
  
    // Set the layout of the panel to a BorderLayout
    //setLayout(new BorderLayout());
    setLayout(new GridLayout(4,1));

    // Create a label for the group
    JLabel label = new JLabel("Available schemes ");
    add(label);

    // Add a new radio button to the pane
    radioButton = new JRadioButton("Option 1");
    radioButton.setActionCommand("Option 1");
    radioButton.setMnemonic ('a');
    radioButton.setToolTipText("Some tip text for option 1...");
    add (radioButton);
    rbg.add (radioButton);
    radioButton.addActionListener(new InnerAbstractAction());
  
    // Set up more radio buttons
    radioButton = new JRadioButton("Option 2");
    radioButton.setActionCommand("Option 2");
    radioButton.setMnemonic ('b');
    radioButton.setToolTipText("Some tip text for option 2...");
    add (radioButton);
    rbg.add (radioButton);
    radioButton.addActionListener(new InnerAbstractAction());

    radioButton = new JRadioButton("Option 3");
    radioButton.setActionCommand("Option 3");
    radioButton.setMnemonic ('c');
    radioButton.setToolTipText("Some tip text for option 3...");
    add (radioButton);
    rbg.add (radioButton);
    radioButton.addActionListener(new InnerAbstractAction());
    // Set this radio button to be the default
    radioButton.setSelected(true);
    currentSelection = "Option 3";

  
    // Adjust to preferred size
    sizeToFit();
  }
  

  /*
   * Apply preferred size
   */
  private void sizeToFit() {
    Dimension d = new Dimension(getPreferredSize());
    setSize(d);
    doLayout();
    Component p = getParent();
      if (p != null) {
        p.invalidate();
        p.doLayout();
      }
  }

  /**
   * Get the insets
   */
  public synchronized Insets getInsets()
  { return insets; }
  
  /**
   * Set the insets
   */
  public synchronized void setInsets(int n1, int n2, int n3, int n4) {
    this.insets = new Insets(n1,n2,n3,n4);
  }

  /**
   * Get the current selection
   */
  public String getSelection() {
    String checkboxLabel = rbg.getSelection().getActionCommand();
    return checkboxLabel;
  }

  /**
   * Set the current selection
   */
  public void setSelection(String ac) {

    String oldSelection = currentSelection;
    currentSelection = ac;
    changes.firePropertyChange("selection", new String(oldSelection), new
String(currentSelection));
    updateSelection(ac);
    fireChange();
  }

  /*
   * Update the selection from an action command string
   */
  private void updateSelection(String ac) {

    Enumeration e = rbg.getElements();
    AbstractButton ab;
    while(e.hasMoreElements())
      {
      ab = (AbstractButton)e.nextElement();
      if(ab.getActionCommand().equals(ac))
        {
        String oldSelection = currentSelection;
        currentSelection = ac;
        ab.setSelected(true);
        }
      else
        {
        ab.setSelected(false);
        }
      }
  }

  /**
   * This is used in the context of the MVC
   * design pattern
   *
   * Listener notification support
   */
  public void addChangeListener(ChangeListener x) {
    changeListeners.add (ChangeListener.class, x);

    // bring it up to date with current state
    x.stateChanged(new ChangeEvent(this));
  }

  public void removeChangeListener(ChangeListener x) {
    changeListeners.remove (ChangeListener.class, x);
  }

  protected void fireChange() {
    // Create the event:
    ChangeEvent c = new ChangeEvent(this);
    // Get the listener list
    Object[] listeners = changeListeners.getListenerList();
    // Process the listeners last to first
    // List is in pairs, Class and instance
    for (int i = listeners.length-2; i >= 0; i -= 2) {
      if (listeners[i] == ChangeListener.class) {
        ChangeListener cl = (ChangeListener)listeners[i+1];
        cl.stateChanged(c);
      }
    }
  }

  /**
   * The specified PropertyChangeListeners <b>propertyChange</b> method will
   * be called each time the value of any bound property is changed.
   * The PropertyListener object is addded to a list of
PropertyChangeListeners
   * managed by this button, it can be removed with
removePropertyChangeListener.
   * Note: the JavaBeans specification does not require
PropertyChangeListeners
   * to run in any particular order.
   *
   * @see #removePropertyChangeListener
   * @param l the PropertyChangeListener
   */
    public void addPropertyChangeListener(PropertyChangeListener l) {
 changes.addPropertyChangeListener(l);
    }

  /**
   * Remove this PropertyChangeListener from the buttons internal list.
   * If the PropertyChangeListener isn't on the list, silently do nothing.
   *
   * @see #addPropertyChangeListener
   * @param l the PropertyChangeListener
   */
    public void removePropertyChangeListener(PropertyChangeListener l) {
 changes.removePropertyChangeListener(l);
    }
  

  /**
   * Inner class to support Abstract Actions for every schemes
   */
  public class InnerAbstractAction implements ActionListener {
    public InnerAbstractAction()
      {}
    public boolean isEnabled() { return true; }
    public void actionPerformed(ActionEvent e)
      {
      setSelection(rbg.getSelection().getActionCommand());
      }
  }
  

}
(Review ID: 32699)
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