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Do not show mainactivity again until app fully restarts

I have an application which has a main activity. When it switches to a second activity I do it like this :
startActivity(intent);
finish();
I was hoping this would fully prevent the application from going back to the main activity. When I press the android back button in the secnond activity it goes back to the home screen (which is what I want). But when I open the app again from multitasking it goes back to the first activity! Has anyone run into this issue before?

I was running into this problem, where my first screen would be a login activity that's only meant to show if the user is not logged in. Otherwise, it show the home screen. I tried out SharedPreferences for login persistence, but it turns out the authentication service I'm using, Google Firebase, has built-in login persistence.
Without more information, however, I can only suggest that you research SharedPreferences and have a boolean check a condition upon start-up. If the condition is met, start the home activity; otherwise, show the main activity. Something like:
boolean isLogin;
SharedPreferences settings;
SharedPreferences.Editor editor;
settings = getApplicationContext().getSharedPreferences("MyPrefs", MODE_PRIVATE);
isLogin = settings.getBoolean("islogin", false);
if(isLogin) {
finish();
goToDash();
}
Public Interface Shared Preferences, Android Developers
Obtaining Shared Preferences
Working with Android Shared Preferences

Figured it out! My application uses a twitter api, and relaunching the application would cause an error as it retried to get credentials it didn't have before. I also made sure to completely clear the stack when switching certain applications by doing:
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK|Intent.FLAG_ACTIVITY_NEW_TASK);

onTaskRemoved not being called in service above android 6.please can some one give better alternative

I've been using onTaskRemoved() method in a Service to detect when an app was removed from the device's RECENT list by swiping it away. I preform some logging and some other operations that need to take place when this happens. It works perfectly. For android below 6... But background service is being killed after swiping off in android 6.
#Override
public void onTaskRemoved(Intent rootIntent) {
Log.e("ClearFromRecentSsss", "sttttts");
Intent intent = new Intent("in.com.example");
sendBroadcast(intent);
}

Some manufactures like xiaomi, Oppo have their own background strategy which is autostart. You need to redirect user to auto start activity and tell user to switch on:
Go like this and allow your app to autostart:
Settings > permissions > Autostart
Autostart setting varies by manufactures like in Xiaomi you can find it in their SecurityCenter app.
Autostart is blocking your service to restart, So turn it on manually and the check again . I'm afraid there is no inbuilt API to do so . So you need to redirect users to specified screen as per manufactures to turn auto start On. Have a look at Links below:
link1
link2

Check whether an activity is active or not from a different activity

I have a flow in my application like this:
For new users:
Splash Screen --> Login Activity --> Home Activity
For already registered users:
Splash Screen --> Home Activity
Basically the Splash Screen has an if else to decide which activity to go to. Once a first time user logs in, his status is saved in a preference variable for the splash screen to decide next time not to open the login activity.
Now the situation is that. If a new user logs in and goes to the home activity, and then logs out. He is redirected to the Login screen which is pretty much what should happen. But, in case an existing user opens the app, he is shown the Splash screen and directly moved to the Home Activity. Now if the user logs out, he gets out of the app. This happens because the Login Activity does not have any instance created and thus finishing the Home Activity finishes the whole app. Logout actually finishes the Home Activity, naturally the last active activity should open up. Which is not happening.
What I want to do is that, I want to implement a logic which will check that the Login Activity is available or not. If its available then finish() will be called else the Login Activity will be called via intent.
Please tell me how to achieve this.
P.S: My app uses a custom theme with a customized action bar. If I call finish and Intent together or I use flags to clear existing activities then there is a weird transition effect which shows the black standard action bar for a split second thus creating a bad user experience.

Now if the user logs out, he gets out of the app. This happens because
the Login Activity does not have any instance created and thus
finishing the Home Activity finishes the whole app.
If i understood your question, why dont you just call the Login Activity manually after user click a logout button?
Its what i always did with apps that have flow like yours

when user login finish login activity and start home activity.
when user logout finish home activity and start login activity

You always can call Login Activity via intent. If the activity is available, android will show this activity. Else android will create new activity automatically.
Actually that's why we use intents to show activity instead of creating activityes manually. System catches this intents and does all dirty work.

EDIT:
Hmm, but wouldn't you have the transition problem anyways? (If you were already logged in, and then log out - using intent/finish() you will have the same black action bar issue no?)
Maybe consider following ( I actually did this in my app):
Merge Splash screen and Login into one activity and depending whether you are logged in - display the login fields or proceed to home screen. Then you have a out of box consistent stack of activities regardless of use cases and no mambo-jumbo with do I already have this or not.
I can't comment because of I lack 4 rep, so I'll post as answer here:
I think #Blaze Tama is right. You can also use FLAG_ACTIVITY_CLEAR_TOP on intent to avoid stack flow problems:
From docs:
If set, and the activity being launched is already running in the current task, then instead of launching a new instance of that activity, all of the other activities on top of it will be closed and this Intent will be delivered to the (now on top) old activity as a new Intent.

Always start Login activity and start Home activity right away if the user already logged in.
In the Splash Screen activity
Intent intent = new Intent(this, Login.class);
If (user already logged in)
{
intent.putextra("Logged in", true);
}
startActivity(intent);
In the Login activity
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
Intent intent = getIntent();
if (intent != null)
{
if (intent.getBooleanExtra("Logged in", false))
{
startActivityForResult(new Intent(this, Home.class), requestCode);
}
}
else
{
// The existing code here
}
}
In Home activity send back a code to indicate if the user logged out or just BackPress. If BackPress finish this Login activity.

Android 4.2.2 back button issue

I have developed a custom launcher for android. The launcher is working fine except for a 'bug' that it has.
I have given the user certain shortcuts on the main screen for accessibility.
Now suppose the user starts the Youtube activity. When the user presses the back button it goes back to the launcher, which is fine.
I am invoking the activity like this
PackageManager manager = context.getPackageManager();
context.startActivity(manager.getLaunchIntentForPackage(youtubeactivitystring));
I have also provided a shortcut to a browser activity for help on the main screen which is invoked as follows:
Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://url/content/help"));
context.startActivity(browserIntent);
When the user clicks on HELP he is unable to get out of the browser (it's stuck there for some reason). When the user clicks the HOME button, the user lands on the launcher. When the user goes back to start another activity (say youtube again) and then get out the activity by clicking the BACK button, somehow the browser activity opens. I am unable to understand why is this happening.
Please help

Android, Opening app only if it is closed through intent action

I am working on a phonegap application, with some native pieces.
So far I have notifications running natively, to make sure javascript and phonegap is not required at all. The problem I am having however, is when the notification is clicked I'd like to open the app, or otherwise just bring the app to the front.
How do I do this? I tried setting the main activity in the intent, but it restarts my application every time.
Intent notificationIntent = new Intent(context, main.app.class);
notificationIntent.putExtra(NOTIF_RESPOND, runThis);
notificationIntent.setAction(Intent.ACTION_VIEW);
notificationIntent = notificationIntent.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);

Actually in Android there is almost no such thing as "restarting application". Basically the Application - is a bundle of all your services/activities/providers etc. It's either running or not.
If user starts a new Activity - system will check, if application is running - it will create this activity inside the application. If no - will create new Application instance.
So I think you mean that if you set intent for your Main activity - another instance of Activity is launching, am I right?
If so - take a look at the following flag for activity, you should try to set in in the Manifest(or whatever in PhoneGap, sorry). http://developer.android.com/guide/topics/manifest/activity-element.html#lmode
<activity android:name=".YourActivity"
android:launchMode="singleTask"
...
This flag will tell the system not to create a new Activity each type it will be needed, but to reuse already-existing one. Be careful, you should properly implement onNewIntent method in this case to handle this "relaunches", and I'm not 100% sure that it's implemented in PhoneGap.
Good luck