AbstractAction.java

/* AbstractAction.java --
   Copyright (C) 2002, 2004, 2005, 2006  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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permission to link this library with independent modules to produce an
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package javax.swing;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.Serializable;
import java.util.HashMap;

import javax.swing.event.SwingPropertyChangeSupport;

/**
 * A base class for implementing the {@link Action} interface.
 *
 * @author Andrew Selkirk
 */
public abstract class AbstractAction
  implements Action, Cloneable, Serializable
{
  private static final long serialVersionUID = -6803159439231523484L;

  /**
   * A flag that indicates whether or not the action is enabled.
   */
  protected boolean enabled = true;

  /**
   * Provides support for property change event notification.
   */
  protected SwingPropertyChangeSupport changeSupport =
    new SwingPropertyChangeSupport(this);

  /**
   * store
   */
  private transient HashMap store = new HashMap();

  /**
   * Creates a new action with no properties set.
   */
  public AbstractAction()
  {
    // Nothing to do.
  }

  /**
   * Creates a new action with the specified name.  The name is stored as a
   * property with the key {@link Action#NAME}, and no other properties are
   * initialised.
   *
   * @param name  the name (<code>null</code> permitted).
   */
  public AbstractAction(String name)
  {
    putValue(NAME, name);
  }

  /**
   * Creates a new action with the specified name and icon.  The name is stored
   * as a property with the key {@link Action#NAME}, the icon is stored as a
   * property with the key {@link Action#SMALL_ICON}, and no other properties
   * are initialised.
   *
   * @param name  the name (<code>null</code> permitted).
   * @param icon  the icon (<code>null</code> permitted).
   */
  public AbstractAction(String name, Icon icon)
  {
    putValue(NAME, name);
    putValue(SMALL_ICON, icon);
  }

  /**
   * Returns a clone of the action.
   *
   * @return A clone of the action.
   *
   * @exception CloneNotSupportedException if there is a problem cloning the
   *            action.
   */
  protected Object clone() throws CloneNotSupportedException
  {
    AbstractAction copy = (AbstractAction) super.clone();
    copy.store = (HashMap) store.clone();
    return copy;
  }

  /**
   * Returns the value associated with the specified key.
   *
   * @param key  the key (not <code>null</code>).
   *
   * @return The value associated with the specified key, or
   *         <code>null</code> if the key is not found.
   *
   * @see #putValue(String, Object)
   */
  public Object getValue(String key)
  {
    return store.get(key);
  }

  /**
   * Sets the value associated with the specified key and sends a
   * {@link java.beans.PropertyChangeEvent} to all registered listeners.
   * The standard keys are:
   * <ul>
   * <li>{@link #NAME}</li>
   * <li>{@link #SHORT_DESCRIPTION}</li>
   * <li>{@link #LONG_DESCRIPTION}</li>
   * <li>{@link #SMALL_ICON}</li>
   * <li>{@link #ACTION_COMMAND_KEY}</li>
   * <li>{@link #ACCELERATOR_KEY}</li>
   * <li>{@link #MNEMONIC_KEY}</li>
   * </ul>
   * Any existing value associated with the key will be overwritten.
   *
   * @param key  the key (not <code>null</code>).
   * @param value  the value (<code>null</code> permitted).
   */
  public void putValue(String key, Object value)
  {
    Object old = getValue(key);
    if ((old == null && value != null) || (old != null && !old.equals(value)))
    {
      store.put(key, value);
      firePropertyChange(key, old, value);
    }
  }

  /**
   * Returns the flag that indicates whether or not the action is enabled.
   *
   * @return The flag.
   *
   * @see #setEnabled(boolean)
   */
  public boolean isEnabled()
  {
    return enabled;
  }

  /**
   * Sets the flag that indicates whether or not the action is enabled and, if
   * the value of the flag changed from the previous setting, sends a
   * {@link java.beans.PropertyChangeEvent} to all registered listeners (using
   * the property name 'enabled').
   *
   * @param enabled  the new flag value.
   *
   * @see #isEnabled()
   */
  public void setEnabled(boolean enabled)
  {
    if (enabled != this.enabled)
    {
      this.enabled = enabled;
      firePropertyChange("enabled", !this.enabled, this.enabled);
    }
  }

  /**
   * Returns an array of the keys for the property values that have been
   * defined via the {@link #putValue(String, Object)} method (or the class
   * constructor).
   *
   * @return An array of keys.
   */
  public Object[] getKeys()
  {
    return store.keySet().toArray();
  }

  /**
   * Sends a {@link PropertyChangeEvent} for the named property to all
   * registered listeners.
   *
   * @param propertyName  the property name.
   * @param oldValue  the old value of the property.
   * @param newValue  the new value of the property.
   */
  protected void firePropertyChange(String propertyName, Object oldValue,
                                    Object newValue)
  {
    changeSupport.firePropertyChange(propertyName, oldValue, newValue);
  }

  /**
   * Sends a {@link PropertyChangeEvent} for the named property to all
   * registered listeners.  This private method is called by the
   * {@link #setEnabled(boolean)} method.
   *
   * @param propertyName  the property name.
   * @param oldValue  the old value of the property.
   * @param newValue  the new value of the property.
   */
  private void firePropertyChange(String propertyName, boolean oldValue,
                                  boolean newValue)
  {
    changeSupport.firePropertyChange(propertyName, oldValue, newValue);
  }

  /**
   * Registers a listener to receive {@link PropertyChangeEvent} notifications
   * from this action.
   *
   * @param listener the listener.
   *
   * @see #removePropertyChangeListener(PropertyChangeListener)
   */
  public void addPropertyChangeListener(PropertyChangeListener listener)
  {
    changeSupport.addPropertyChangeListener(listener);
  }

  /**
   * Deregisters a listener so that it no longer receives
   * {@link PropertyChangeEvent} notifications from this action.
   *
   * @param listener the listener.
   *
   * @see #addPropertyChangeListener(PropertyChangeListener)
   */
  public void removePropertyChangeListener(PropertyChangeListener listener)
  {
    changeSupport.removePropertyChangeListener(listener);
  }

  /**
   * Returns all registered listeners.
   *
   * @return An array of listeners.
   *
   * @since 1.4
   */
  public PropertyChangeListener[] getPropertyChangeListeners()
  {
    return changeSupport.getPropertyChangeListeners();
  }
}