https://source.android.com/ 
/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.view;

import android.view.MenuItem.OnActionExpandListener;


When a View implements this interface it will receive callbacks when expanded or collapsed as an action view alongside the optional, app-specified callbacks to OnActionExpandListener. 
See MenuItem for more information about action views. See ActionBar for more information about the action bar. 
/**
 * When a {@link View} implements this interface it will receive callbacks
 * when expanded or collapsed as an action view alongside the optional,
 * app-specified callbacks to {@link OnActionExpandListener}.
 *
 * <p>See {@link MenuItem} for more information about action views.
 * See {@link android.app.ActionBar} for more information about the action bar.
 */
public interface CollapsibleActionView {
    
Called when this view is expanded as an action view. See MenuItem.expandActionView(). 
/**
     * Called when this view is expanded as an action view.
     * See {@link MenuItem#expandActionView()}.
     */
    public void onActionViewExpanded();

    
Called when this view is collapsed as an action view. See MenuItem.collapseActionView(). 
/**
     * Called when this view is collapsed as an action view.
     * See {@link MenuItem#collapseActionView()}.
     */
    public void onActionViewCollapsed();
}