check android application is in foreground or not? [duplicate]

Answer 1

None of the solutions base on getRunningTasks() works in recent Android versions, getRunningTasks() was deprecated in API level 21. Even if it is still used it does not return enough information to determine if the app is in the foreground.

Instead extend the Application class and use Application.ActivityLifecycleCallbacks to track application visibility state.

public class MyApplication extends Application {
    static final String APP_STATE_FOREGROUND = "com.xxx.appstate.FOREGROUND";
    static final String APP_STATE_BACKGROUND = "com.xxx.appstate.BACKGROUND";
    private static int m_foreground = -1;
    private Handler m_handler = new Handler();
    private Runnable m_guard;

    public static boolean isForeground() {
        return m_foreground == 1;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        registerActivityLifecycleCallbacks(new Application.ActivityLifecycleCallbacks() {

            @Override
            public void onActivityCreated(Activity activity, Bundle bundle) {
            }

            @Override
            public void onActivityStarted(Activity activity) {
            }

            @Override
            public void onActivityResumed(Activity activity) {
                if(m_guard != null) {
                    m_handler.removeCallbacks(m_guard);
                    m_guard = null;
                }
                if(m_foreground == 1)
                    return;
                m_foreground = 1;
                sendBroadcast(new Intent(APP_STATE_FOREGROUND));
            }

            @Override
            public void onActivityPaused(Activity activity) {
                if(m_foreground == 0)
                    return;
                /*
                 * Use a 400ms guard to protect against jitter
                 * when switching between two activities
                 * in the same app
                 */
                m_guard = new Runnable() {
                    @Override
                    public void run() {
                        if(m_foreground == 1) {
                            m_foreground = 0;
                            sendBroadcast(new Intent(APP_STATE_BACKGROUND));
                        }
                    }
                };
                m_handler.postDelayed(m_guard, 400);
            }

            @Override
            public void onActivityStopped(Activity activity) {
            }

            @Override
            public void onActivitySaveInstanceState(Activity activity, Bundle bundle) {
            }

            @Override
            public void onActivityDestroyed(Activity activity) {
            }
        });
    }
}

Using the 400ms guard timer eliminates false detection of background state when switching between activities in the same app. The background/foreground state can be queried at anytime using:

MyApplication.isForeground();

A class can also listen for the broadcast events if it is interested in the state transitions:

private static IntentFilter m_appStateFilter;

static {
    m_appStateFilter = new IntentFilter();
    m_appStateFilter.addAction(MyApplication.APP_STATE_FOREGROUND);
    m_appStateFilter.addAction(MyApplication.APP_STATE_BACKGROUND);
}

private BroadcastReceiver m_appStateReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if (action.equals(MyApplication.APP_STATE_FOREGROUND)) {
            /* application entered foreground */
        } else if (action.equals(MyApplication.APP_STATE_BACKGROUND)) {
            /* application entered background */
        }
    }
};
registerReceiver(m_appStateReceiver, m_appStateFilter);