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

String appPackageName = "";

private void isApplicationInForeground() throws Exception {
    ActivityManager am = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        final List processInfos = am
                .getRunningAppProcesses();
        ActivityManager.RunningAppProcessInfo processInfo = processInfos
                .get(0);
        // for (ActivityManager.RunningAppProcessInfo processInfo : processInfos) {
        if (processInfo.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
            // getting process at 0th index means our application is on top on all apps or currently open 
            appPackageName = (Arrays.asList(processInfo.pkgList).get(0));
        }
        // }
    }
    else {
        List taskInfo = am.getRunningTasks(1);
        ComponentName componentInfo = null;
        componentInfo = taskInfo.get(0).topActivity;
        appPackageName = componentInfo.getPackageName();
    }
}

private void notifyMessage(String text) {
    if (appPackageName.contains("com.example.test")) {
        // do not notify
    }
    else {          
        // create notification and notify user  
    }
}