260 lines
9.0 KiB
Java
Executable File
260 lines
9.0 KiB
Java
Executable File
// Copyright 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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package org.chromium.base;
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import android.app.Activity;
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import android.app.Application;
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import android.app.Application.ActivityLifecycleCallbacks;
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import android.os.Bundle;
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import java.util.HashMap;
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import java.util.Map;
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/**
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* Provides information about the current activity's status, and a way
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* to register / unregister listeners for state changes.
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*/
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@JNINamespace("base::android")
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public class ActivityStatus {
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// Constants matching activity states reported to StateListener.onStateChange
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// As an implementation detail, these are now defined in the auto-generated
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// ActivityState interface, to be shared with C++.
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public static final int CREATED = ActivityState.CREATED;
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public static final int STARTED = ActivityState.STARTED;
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public static final int RESUMED = ActivityState.RESUMED;
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public static final int PAUSED = ActivityState.PAUSED;
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public static final int STOPPED = ActivityState.STOPPED;
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public static final int DESTROYED = ActivityState.DESTROYED;
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// Last activity that was shown (or null if none or it was destroyed).
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private static Activity sActivity;
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private static final Map<Activity, Integer> sActivityStates =
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new HashMap<Activity, Integer>();
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private static final ObserverList<StateListener> sStateListeners =
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new ObserverList<StateListener>();
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/**
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* Interface to be implemented by listeners.
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*/
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public interface StateListener {
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/**
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* Called when the activity's state changes.
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* @param newState New activity state.
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*/
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public void onActivityStateChange(int newState);
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}
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private ActivityStatus() {}
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/**
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* Initializes the activity status for a specified application.
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*
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* @param application The application whose status you wish to monitor.
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*/
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public static void initialize(Application application) {
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application.registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() {
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@Override
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public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
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onStateChange(activity, CREATED);
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}
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@Override
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public void onActivityDestroyed(Activity activity) {
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onStateChange(activity, DESTROYED);
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}
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@Override
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public void onActivityPaused(Activity activity) {
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onStateChange(activity, PAUSED);
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}
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@Override
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public void onActivityResumed(Activity activity) {
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onStateChange(activity, RESUMED);
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}
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@Override
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public void onActivitySaveInstanceState(Activity activity, Bundle outState) {}
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@Override
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public void onActivityStarted(Activity activity) {
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onStateChange(activity, STARTED);
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}
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@Override
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public void onActivityStopped(Activity activity) {
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onStateChange(activity, STOPPED);
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}
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});
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}
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/**
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* Must be called by the main activity when it changes state.
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*
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* @param activity Current activity.
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* @param newState New state value.
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*/
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private static void onStateChange(Activity activity, int newState) {
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if (activity == null) throw new IllegalArgumentException("null activity is not supported");
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if (sActivity != activity) {
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// ActivityStatus is notified with the CREATED event very late during the main activity
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// creation to avoid making startup performance worse than it is by notifying observers
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// that could do some expensive work. This can lead to non-CREATED events being fired
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// before the CREATED event which is problematic.
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// TODO(pliard): fix http://crbug.com/176837.
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if (sActivity == null
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|| newState == CREATED || newState == RESUMED || newState == STARTED) {
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sActivity = activity;
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}
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}
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if (newState != DESTROYED) {
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sActivityStates.put(activity, newState);
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} else {
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sActivityStates.remove(activity);
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}
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if (sActivity == activity) {
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for (StateListener listener : sStateListeners) {
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listener.onActivityStateChange(newState);
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}
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if (newState == DESTROYED) {
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sActivity = null;
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}
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}
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}
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/**
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* Testing method to update the state of the specified activity.
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*/
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public static void onStateChangeForTesting(Activity activity, int newState) {
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onStateChange(activity, newState);
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}
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/**
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* @return The current activity.
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*/
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public static Activity getActivity() {
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return sActivity;
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}
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/**
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* @return The current activity's state (if no activity is registered, then DESTROYED will
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* be returned).
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*/
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public static int getState() {
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return getStateForActivity(sActivity);
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}
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/**
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* Query the state for a given activity. If the activity is not being tracked, this will
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* return {@link #DESTROYED}.
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*
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* <p>
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* When relying on this method, be familiar with the expected life cycle state
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* transitions:
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* <a href="http://developer.android.com/guide/components/activities.html#Lifecycle">
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* Activity Lifecycle
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* </a>
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*
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* <p>
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* During activity transitions (activity B launching in front of activity A), A will completely
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* paused before the creation of activity B begins.
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*
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* <p>
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* A basic flow for activity A starting, followed by activity B being opened and then closed:
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* <ul>
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* <li> -- Starting Activity A --
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* <li> Activity A - CREATED
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* <li> Activity A - STARTED
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* <li> Activity A - RESUMED
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* <li> -- Starting Activity B --
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* <li> Activity A - PAUSED
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* <li> Activity B - CREATED
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* <li> Activity B - STARTED
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* <li> Activity B - RESUMED
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* <li> Activity A - STOPPED
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* <li> -- Closing Activity B, Activity A regaining focus --
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* <li> Activity B - PAUSED
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* <li> Activity A - STARTED
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* <li> Activity A - RESUMED
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* <li> Activity B - STOPPED
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* <li> Activity B - DESTROYED
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* </ul>
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*
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* @param activity The activity whose state is to be returned.
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* @return The state of the specified activity.
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*/
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public static int getStateForActivity(Activity activity) {
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Integer currentStatus = sActivityStates.get(activity);
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return currentStatus != null ? currentStatus.intValue() : DESTROYED;
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}
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/**
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* Registers the given listener to receive activity state changes.
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* @param listener Listener to receive state changes.
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*/
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public static void registerStateListener(StateListener listener) {
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sStateListeners.addObserver(listener);
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}
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/**
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* Unregisters the given listener from receiving activity state changes.
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* @param listener Listener that doesn't want to receive state changes.
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*/
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public static void unregisterStateListener(StateListener listener) {
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sStateListeners.removeObserver(listener);
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}
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/**
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* Registers the single thread-safe native activity status listener.
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* This handles the case where the caller is not on the main thread.
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* Note that this is used by a leaky singleton object from the native
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* side, hence lifecycle management is greatly simplified.
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*/
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@CalledByNative
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private static void registerThreadSafeNativeStateListener() {
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ThreadUtils.runOnUiThread(new Runnable () {
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@Override
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public void run() {
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// Register a new listener that calls nativeOnActivityStateChange.
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sStateListeners.addObserver(new StateListener() {
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@Override
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public void onActivityStateChange(int newState) {
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nativeOnActivityStateChange(newState);
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}
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});
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}
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});
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}
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// Called to notify the native side of state changes.
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// IMPORTANT: This is always called on the main thread!
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private static native void nativeOnActivityStateChange(int newState);
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/**
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* Checks whether or not the Application's current Activity is visible to the user. Note that
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* this includes the PAUSED state, which can happen when the Activity is temporarily covered
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* by another Activity's Fragment (e.g.).
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* @return True if the Activity is visible, false otherwise.
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*/
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public static boolean isApplicationVisible() {
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int state = getState();
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return state != STOPPED && state != DESTROYED;
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}
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/**
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* Checks to see if there are any active Activity instances being watched by ActivityStatus.
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* @return True if all Activities have been destroyed.
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*/
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public static boolean isEveryActivityDestroyed() {
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return sActivityStates.isEmpty();
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}
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}
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