Android: new Intent() starts new instance with android:launchMode="singleTop"

Question

I have Activity A with android:launchMode="singleTop" in the manifest.

If I go to Activity B, C and D there I have menu shortcuts to return to my applications root activity (A).

The code looks like this:

Intent myIntent = new Intent(getBaseContext(), MainActivity.class);
startActivity(myIntent);

However, instead of returning to the already existing instance A of my MainActivity.class it creates a new instance -> it goes to onCreate() instead of onNewIntent().

This is not the expected behavior, right?

Answer 1

Quote from the documentation:

The "standard" and "singleTop" modes differ from each other in just one respect: Every time there's new intent for a "standard" activity, a new instance of the class is created to respond to that intent. Each instance handles a single intent. Similarly, a new instance of a "singleTop" activity may also be created to handle a new intent. However, if the target task already has an existing instance of the activity at the top of its stack, that instance will receive the new intent (in an onNewIntent() call); a new instance is not created.

I'm not 100% sure what "already has an existing instance of the activity at the top of its stack" means, but perhaps your activity isn't meeting this condition.

Would singleTask or singleInstance work for you? Or perhaps you could try setting FLAG_ACTIVITY_SINGLE_TOP on the intent you are creating to see if that makes a difference, although I don't think it will.

Answer 2

This should do the trick.

<activity ... android:launchMode="singleTop" />

When you create an intent to start the app use:

Intent intent= new Intent(context, YourActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_SINGLE_TOP);

This is that should be needed.

Answer 3

What actually worked for me in the end was this:

Intent myIntent = new Intent(getBaseContext(), MainActivity.class);
myIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(myIntent);