android – Bring application to front after user clicks on home button-ThrowExceptions

Exception or error:

My application is in running mode[foreground] and user clicks on home button, which puts application to background[and still running]. I have alarm functionality in my application which fires up. I want is when my alarm goes off i want to bring my background running application in foreground and from last state in which it was.

    <application
            android:name="com.abc.android.state.management.MainEPGApp"
            android:icon="@drawable/icon"
            android:label="@string/app_name"
            android:largeHeap="true"
            android:logo="@drawable/app_logo" >
            <activity
                android:name=".SplashScreen"
                android:label="@string/app_name"
                android:launchMode="singleTop"
                android:screenOrientation="nosensor"
                android:theme="@style/Theme.Sherlock" >
                <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
            </activity>
        <activity
                    android:name=".Starter"
                    android:configChanges="orientation|screenSize"
                    android:screenOrientation="behind"
                    android:launchMode="singleTop"
                    android:uiOptions="none"
                    android:windowSoftInputMode="adjustPan" />
</application>
How to solve:
Intent intent = new Intent(context, MyRootActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK|Intent.FLAG_ACTIVITY_SINGLE_TOP);
startActivity(intent);

You should use your starting or root activity for MyRootActivity.

This will bring an existing task to the foreground without actually creating a new Activity. If your application is not running, it will create an instance of MyRootActivity and start it.

EDIT

I added Intent.FLAG_ACTIVITY_SINGLE_TOP to Intent to make it really work!

Second EDIT

There is another way to do this. You can simulate the “launching” of the app the same way that Android launches the app when the user selects it from the list of available apps. If the user starts an application that is already running, Android just brings the existing task to the foreground (which is what you want). Do it like this:

Intent intent = new Intent(context, SplashScreen.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); // You need this if starting
                                                //  the activity from a service
intent.setAction(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_LAUNCHER);
startActivity(intent);

###

You can use the below code to bring the application to front:

private void bringApplicationToFront()
    {

        Log.d(TAG, "====Bringging Application to Front====");

        Intent notificationIntent = new Intent(this, MainActivity.class);
        notificationIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);
        try 
        {
            pendingIntent.send();
        }
        catch (CanceledException e) 
        {
            e.printStackTrace();
        }
    }

###

A combination that works for me is to use:

Intent bringToForegroundIntent = new Intent(context, RootActivity.class);
bringToForegroundIntent.setFlags(Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED | Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(bringToForegroundIntent);

If you check the logs on the device whenever you start an activity from a launcher icon this is the intent that gets passed to launch the app or move it back to foreground if e.g. user clicked the Home button.

###

I find a new way to bring app to foreground,
It imitate click Icon to launch application.

    PackageManager packageManager = context.getPackageManager();
    Intent intent = packageManager.getLaunchIntentForPackage(pkName);
    if (intent != null)
    {
            //模拟点击桌面图标的启动参数
            intent.setPackage(null);
         // intent.setSourceBounds(new Rect(804,378, 1068, 657));
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK|Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED);
           context.startActivity(intent);

    }

it work for me, But who can tell me why package must be null

###

From my test, to mimic the Launcher behavior, the key is to:

intent.setPackage(null);

after

Intent intent = packageManager.getLaunchIntentForPackage(pkName);

Other methods in this thread doesn’t work in my case.

Thanks to jiaqing’s answer, I post this answer as I don’t have the right to comment. I don’t know the logic behind this either, I guess it’s related with the task owner. Anyone knows, would be glad to know.

###

For an alarm, you want to take a look at starting an Android Service

This service will be more resilient than your application which may be killed while in the background and can fire off an intent to bring your application to the front (or restart it if it was killed) when it is time for the alarm to go off.

###

Using the ActivityManager class you can bring a running task to front

void bringToFront(){

 ActivityManager activtyManager = (ActivityManager)getSystemService(Context.ACTIVITY_SERVICE);
 List<ActivityManager.RunningTaskInfo> runningTaskInfos = activtyManager.getRunningTasks(3);
 for (ActivityManager.RunningTaskInfo runningTaskInfo : runningTaskInfos)
            {
              if (this.getPackageName().equals(runningTaskInfo.topActivity.getPackageName()))
                {
                     activtyManager.moveTaskToFront(runningTaskInfo.id, ActivityManager.MOVE_TASK_WITH_HOME);
                     return;
                 }
             }
}

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