/*
 * @(#)JRadioButtonMenuItem.java	1.42 00/04/06
 *
 * Copyright 1997-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */
package javax.swing;

import java.util.EventListener;

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;

import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;

import javax.swing.plaf.*;
import javax.accessibility.*;

/**
 * An implementation of a radio button menu item.
 * A <code>JRadioButtonMenuItem</code> is
 * a menu item that is part of a group of menu items in which only one
 * item in the group can be selected. The selected item displays its
 * selected state. Selecting it causes any other selected item to
 * switch to the unselected state.
 * To control the selected state of a group of radio button menu items,  
 * use a <code>ButtonGroup</code> object.
 * <p>
 * For further documentation and examples see
 * <a
 href="http://java.sun.com/docs/books/tutorial/uiswing/components/menu.html">How to Use Menus</a>,
 * a section in <em>The Java Tutorial.</em>
 * For the keyboard keys used by this component in the standard Look and
 * Feel (L&F) renditions, see the
 * <a href="doc-files/Key-Index.html#JRadioButtonMenuItem">JRadioButtonMenuItem</a> key assignments.
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases.  The current serialization support is appropriate
 * for short term storage or RMI between applications running the same
 * version of Swing.  A future release of Swing will provide support for
 * long term persistence.
 *
 * @beaninfo
 *   attribute: isContainer false
 * description: A component within a group of menu items which can be selected.
 *
 * @version 1.42 04/06/00
 * @author Georges Saab
 * @author David Karlton
 * @see ButtonGroup
 */
public class JRadioButtonMenuItem extends JMenuItem implements Accessible {
    /**
     * @see #getUIClassID
     * @see #readObject
     */
    private static final String uiClassID = "RadioButtonMenuItemUI";

    /**
     * Creates a <code>JRadioButtonMenuItem</code> with no set text or icon.
     */
    public JRadioButtonMenuItem() {
        this(null, null, false);
    }

    /**
     * Creates a <code>JRadioButtonMenuItem</code> with an icon.
     *
     * @param icon the <code>Icon</code> to display on the 
     *		<code>JRadioButtonMenuItem</code>
     */
    public JRadioButtonMenuItem(Icon icon) {
        this(null, icon, false);
    }

    /**
     * Creates a <code>JRadioButtonMenuItem</code> with text.
     *
     * @param text the text of the <code>JRadioButtonMenuItem</code>
     */
    public JRadioButtonMenuItem(String text) {
        this(text, null, false);
    }
    
    /**
     * Creates a radio button menu item whose properties are taken from the 
     * <code>Action</code> supplied.
     *
     * @param  a the <code>Action</code> on which to base the radio
     *		button menu item
     *
     * @since 1.3
     */
    public JRadioButtonMenuItem(Action a) {
        this();
	setAction(a);
    }

    /**
     * Creates a radio button menu item with the specified text
     * and <code>Icon</code>.
     *
     * @param text the text of the <code>JRadioButtonMenuItem</code>
     * @param icon the icon to display on the <code>JRadioButtonMenuItem</code>
     */
    public JRadioButtonMenuItem(String text, Icon icon) {
	this(text, icon, false);
    }

    /**
     * Creates a radio button menu item with the specified text 
     * and selection state.
     *
     * @param text the text of the <code>CheckBoxMenuItem</code>
     * @param selected the selected state of the <code>CheckBoxMenuItem</code>
     */
    public JRadioButtonMenuItem(String text, boolean selected) {
        this(text);
        setSelected(selected);
    }

    /**
     * Creates a radio button menu item with the specified image
     * and selection state, but no text.
     *   
     * @param icon  the image that the button should display
     * @param selected  if true, the button is initially selected;
     *                  otherwise, the button is initially unselected
     */
    public JRadioButtonMenuItem(Icon icon, boolean selected) {
        this(null, icon, selected);
    }

    /**
     * Creates a radio button menu item that has the specified 
     * text, image, and selection state.  All other constructors
     * defer to this one.
     *
     * @param text  the string displayed on the radio button 
     * @param icon  the image that the button should display
     */
    public JRadioButtonMenuItem(String text, Icon icon, boolean selected) {
	super(text, icon);
        setModel(new JToggleButton.ToggleButtonModel());
        setSelected(selected);
    }

    /**
     * Returns the name of the L&F class that renders this component.
     *
     * @return the string "RadioButtonMenuItemUI"
     * @see JComponent#getUIClassID
     * @see UIDefaults#getUI
     */
    public String getUIClassID() {
        return uiClassID;
    }


    /**
     * Overrides <code>Component.requestFocus</code> to not grab focus.
     */
    public void requestFocus() {}


    /** 
     * See <code>readObject</code> and <code>writeObject</code> in
     * <code>JComponent</code> for more 
     * information about serialization in Swing.
     */
    private void writeObject(ObjectOutputStream s) throws IOException {
        s.defaultWriteObject();
	if ((ui != null) && (getUIClassID().equals(uiClassID))) {
	    ui.installUI(this);
	}
    }


    /**
     * Returns a string representation of this
     * <code>JRadioButtonMenuItem</code>.  This method 
     * is intended to be used only for debugging purposes, and the 
     * content and format of the returned string may vary between      
     * implementations. The returned string may be empty but may not 
     * be <code>null</code>.
     * 
     * @return  a string representation of this
     *		<code>JRadioButtonMenuItem</code>
     */
    protected String paramString() {
	return super.paramString();
    }

/////////////////                                                 
// Accessibility support
////////////////

    /**
     * Gets the AccessibleContext associated with this JRadioButtonMenuItem. 
     * For JRadioButtonMenuItems, the AccessibleContext takes the form of an 
     * AccessibleJRadioButtonMenuItem. 
     * A new AccessibleJRadioButtonMenuItem instance is created if necessary.
     *
     * @return an AccessibleJRadioButtonMenuItem that serves as the 
     *         AccessibleContext of this JRadioButtonMenuItem
     */
    public AccessibleContext getAccessibleContext() {
        if (accessibleContext == null) {
            accessibleContext = new AccessibleJRadioButtonMenuItem();
        }
        return accessibleContext;
    }

    /**
     * This class implements accessibility support for the 
     * <code>JRadioButtonMenuItem</code> class.  It provides an 
     * implementation of the Java Accessibility API appropriate to 
     * <code>JRadioButtonMenuItem</code> user-interface elements.
     * <p>
     * <strong>Warning:</strong>
     * Serialized objects of this class will not be compatible with
     * future Swing releases.  The current serialization support is appropriate
     * for short term storage or RMI between applications running the same
     * version of Swing.  A future release of Swing will provide support for
     * long term persistence.
     */
    protected class AccessibleJRadioButtonMenuItem extends AccessibleJMenuItem {
        /**
         * Get the role of this object.
         *
         * @return an instance of AccessibleRole describing the role of the 
         * object
         */
        public AccessibleRole getAccessibleRole() {
            return AccessibleRole.RADIO_BUTTON;
        }
    } // inner class AccessibleJRadioButtonMenuItem
}