libjava/java/awt/Checkbox.java

/* Copyright (C) 2000  Free Software Foundation

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

package java.awt;
import java.awt.event.*;
import java.awt.peer.CheckboxPeer;

/** This class implements a component which has an on/off state.  Two
 * or more Checkboxes can be grouped by a CheckboxGroup.
 * @author Tom Tromey <tromey@redhat.com>
 * @date December 25, 2000
 */
public class Checkbox extends Component implements ItemSelectable
{
  /** Create a new checkbox.
   * @param label The checkbox label.  A null value is the same as "";
   *              this is the default.
   * @param state The initial check state; defaults to false.
   * @param group The CheckboxGroup.  Defaults to null.
   */
  public Checkbox ()
  {
    this (null, null, false);
  }

  public Checkbox (String label)
  {
    this (label, null, false);
  }

  public Checkbox (String label, boolean state)
  {
    this (label, null, state);
  }

  public Checkbox (String label, boolean state, CheckboxGroup group)
  {
    this (label, group, state);
  }

  public Checkbox (String label, CheckboxGroup group, boolean state)
  {
    this.label = label;
    this.group = group;
    this.state = state;
  }

  /** Add a listener for item events.
   * @param listener The listener to add.
   */
  public synchronized void addItemListener (ItemListener listener)
  {
    listeners = AWTEventMulticaster.add (listeners, listener);
  }

  /** This creates the component's peer.  */
  public void addNotify ()
  {
    if (peer == null)
      peer = getToolkit ().createCheckbox (this);
  }

  /** Returns the current CheckboxGroup associated with this
   * Checkbox.  */
  public CheckboxGroup getCheckboxGroup ()
  {
    return group;
  }

  /** Returns the current label; might be null.  */
  public String getLabel ()
  {
    return label;
  }

  /** Returns this checkbox's label if this checkbox is selected.  */
  public Object[] getSelectedObjects ()
  {
    Object[] r;
    if (state)
      {
	r = new Object[1];
	r[0] = label;
      }
    else
      r = new Object[0];
    return r;
  }

  /** Returns the current state of this checkbox.  */
  public boolean getState ()
  {
    return state;
  }

  /** Generates a String representation of this Checkbox's state.  */
  protected String paramString ()
  {
    return ("Checkbox["
	    + "state=" + state + ","
	    + "label=" + label + ","
	    + "group=" + group + "]");
  }

  /** Process an event for this Checkbox.
   * @param event The event the process.
   */
  protected void processEvent (AWTEvent event) 
  {
    if (event instanceof ItemEvent)
      processItemEvent ((ItemEvent) event);
    else
      super.processEvent (event);
  }

  /** Process an item event for this Checkbox.
   * @param event The ItemEvent to process
   */
  protected void processItemEvent (ItemEvent event)
  {
    if (listeners != null)
      listeners.itemStateChanged (event);
  }

  /** Remove an item listener.
   * @param listener Item listener to remove.
   */
  public synchronized void removeItemListener (ItemListener listener)
  {
    listeners = AWTEventMulticaster.remove (listeners, listener);
  }

  /** Set this checkbox's group.
   * @param group The new group.  null means remove the Checkbox from
   *              its group.
   */
  public void setCheckboxGroup (CheckboxGroup group)
  {
    this.group = group;
    if (peer != null)
      {
	CheckboxPeer cp = (CheckboxPeer) peer;
	cp.setCheckboxGroup (group);
      }
  }

  /** Set the checkbox's label.
   * @param label The new label
   */
  public synchronized void setLabel (String label)
  {
    this.label = label;
    if (peer != null)
      {
	CheckboxPeer cp = (CheckboxPeer) peer;
	// FIXME: unclear what to do here; we err on the side of
	// caution.
	cp.setLabel (label == null ? "" : label);
      }
  }

  /** Set the checkbox's state.
   * @param state The new state.
   */
  public void setState (boolean state)
  {
    this.state = state;
    if (peer != null)
      {
	CheckboxPeer cp = (CheckboxPeer) peer;
	cp.setState (state);
      }
  }

  private ItemListener listeners;

  String label;
  CheckboxGroup group;
  boolean state;
}