Starting app only if its not currently running

Question

I am sending push notification to users which when clicking on it opens the app.

My problem is that when the app is already open, clicking on the notification start

Answer 1

first of all set a default Task android:taskAffinity="com.example.testp.yourPreferredName" in your Application element in the Manifest file. Maintain your android:launchMode="singleTask" on your SplashActivity. Now since your SplashActivity is your main entry add this code to both onResume(), onNewIntent() and onCreate() (on a second thought onResume() is not recomended) -follow the comments in the code

//Note these following lines of code will work like magic only if its UPVOTED.
//so upvote before you try it.-or it will crash with SecurityException
ActivityManager am = (ActivityManager) this.getSystemService(ACTIVITY_SERVICE);

List< ActivityManager.RunningTaskInfo > taskInfo = am.getRunningTasks(1000);    
    for(int i =0; i< taskInfo.size(); i++){
        String PackageName = taskInfo.get(i).baseActivity.getPackageName();
        if(PackageName.equals("packagename.appname")){// suppose stackoverflow.answerer.Elltz
            //if the current runing actiivity is not the splash activity. it will be 1
            //only if this is the first time your  is be called as a task
            if(taskInfo.get(i).numActivities >1){
                //other activities are running, so kill this splash dead!! reload!!                 
                finish();
                // i am dying in onCreate..(the user didnt see nothing, that's the good part)
                //about this code. its a silent assassin
            }
            //Operation kill the Splash is done so retreat to base.
            break;
        }
    }

This code will not work on api 21+; to make it work you need to use AppTask, this will save you extra lines of code as you will not be in a Loop to find your Task.

Hope it helps