How to check if an activity is the last one in the activity stack for an application?

I'm going to post the comment of @H9kDroid as the best answer here for people that have a similar question.

You can use isTaskRoot() to know whether the activity is the root of a task.

I hope this helps

UPDATE (Jul 2015):

Since getRunningTasks() get deprecated, from API 21 it's better to follow raukodraug answer or Ed Burnette one (I would prefer second one).

There's possibility to check current tasks and their stack using ActivityManager.

So, to determine if an activity is the last one:

• request android.permission.GET_TASKS permissions in the manifest.

• Use the following code:
  

  ActivityManager mngr = (ActivityManager) getSystemService( ACTIVITY_SERVICE );
  
  List<ActivityManager.RunningTaskInfo> taskList = mngr.getRunningTasks(10);
  
  if(taskList.get(0).numActivities == 1 &&
     taskList.get(0).topActivity.getClassName().equals(this.getClass().getName())) {
      Log.i(TAG, "This is last activity in the stack");
  }
  

Please note, that above code will be valid only if You have single task. If there's possibility that number of tasks will exist for Your application - You'll need to check other taskList elements. Read more about tasks Tasks and Back Stack

Hope this will help new beginners, Based above answers which works for me fine, i am also sharing code snippet so it will be easy to implement.

solution : i used isTaskRoot() which return true if current activity is only activity in your stack and other than i also handle case in which if i have some activity in stack go to last activity in stack instead of opening new custom one.

In your activity

   @Override
    public void onBackPressed() {

        if(isTaskRoot()){
            startActivity(new Intent(currentActivityName.this,ActivityNameYouWantToOpen.class));
            // using finish() is optional, use it if you do not want to keep currentActivity in stack
            finish();
        }else{
            super.onBackPressed();
        }

    }