v4/java/android/support/v4/app/ActivityCompat.java

/*
 * 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.support.v4.app;

import android.app.Activity;
import android.content.Intent;
import android.os.Build;

/**
 * Helper for accessing features in {@link android.app.Activity}
 * introduced after API level 4 in a backwards compatible fashion.
 */
public class ActivityCompat {
    /**
     * Invalidate the activity's options menu, if able.
     *
     * <p>Before API level 11 (Android 3.0/Honeycomb) the lifecycle of the
     * options menu was controlled primarily by the user's operation of
     * the hardware menu key. When the user presses down on the menu key
     * for the first time the menu was created and prepared by calls
     * to {@link Activity#onCreateOptionsMenu(android.view.Menu)} and
     * {@link Activity#onPrepareOptionsMenu(android.view.Menu)} respectively.
     * Subsequent presses of the menu key kept the existing instance of the
     * Menu itself and called {@link Activity#onPrepareOptionsMenu(android.view.Menu)}
     * to give the activity an opportunity to contextually alter the menu
     * before the menu panel was shown.</p>
     *
     * <p>In Android 3.0+ the Action Bar forces the options menu to be built early
     * so that items chosen to show as actions may be displayed when the activity
     * first becomes visible. The Activity method invalidateOptionsMenu forces
     * the entire menu to be destroyed and recreated from
     * {@link Activity#onCreateOptionsMenu(android.view.Menu)}, offering a similar
     * though heavier-weight opportunity to change the menu's contents. Normally
     * this functionality is used to support a changing configuration of Fragments.</p>
     *
     * <p>Applications may use this support helper to signal a significant change in
     * activity state that should cause the options menu to be rebuilt. If the app
     * is running on an older platform version that does not support menu invalidation
     * the app will still receive {@link Activity#onPrepareOptionsMenu(android.view.Menu)}
     * the next time the user presses the menu key and this method will return false.
     * If this method returns true the options menu was successfully invalidated.</p>
     *
     * @param activity Invalidate the options menu of this activity
     * @return true if this operation was supported and it completed; false if it was not available.
     */
    public static boolean invalidateOptionsMenu(Activity activity) {
        if (Build.VERSION.SDK_INT >= 11) {
            ActivityCompatHoneycomb.invalidateOptionsMenu(activity);
            return true;
        }
        return false;
    }

    /**
     * Start a set of activities as a synthesized task stack, if able.
     *
     * <p>In API level 11 (Android 3.0/Honeycomb) the recommended conventions for
     * app navigation using the back key changed. The back key's behavior is local
     * to the current task and does not capture navigation across different tasks.
     * Navigating across tasks and easily reaching the previous task is accomplished
     * through the "recents" UI, accessible through the software-provided Recents key
     * on the navigation or system bar. On devices with the older hardware button configuration
     * the recents UI can be accessed with a long press on the Home key.</p>
     *
     * <p>When crossing from one task stack to another post-Android 3.0,
     * the application should synthesize a back stack/history for the new task so that
     * the user may navigate out of the new task and back to the Launcher by repeated
     * presses of the back key. Back key presses should not navigate across task stacks.</p>
     *
     * <p>startActivities provides a mechanism for constructing a synthetic task stack of
     * multiple activities. If the underlying API is not available on the system this method
     * will return false.</p>
     *
     * @param activity Start activities using this activity as the starting context
     * @param intents Array of intents defining the activities that will be started. The element
     *                length-1 will correspond to the top activity on the resulting task stack.
     * @return true if the underlying API was available and the call was successful, false otherwise
     */
    public static boolean startActivities(Activity activity, Intent[] intents) {
        if (Build.VERSION.SDK_INT >= 11) {
            ActivityCompatHoneycomb.startActivities(activity, intents);
            return true;
        }
        return false;
    }
}