Determining the current foreground application from a background task or service

Question

I wish to have one application that runs in the background, which knows when any of the built-in applications (messaging, contacts, etc) is running.

So my questions

Answer 1

In lollipop and up:

Add to mainfest:

And do something like this:

if( mTaskId < 0 )
{
    List tasks = mActivityManager.getAppTasks(); 
    if( tasks.size() > 0 )
        mTaskId = tasks.get( 0 ).getTaskInfo().id;
}