Service to continuously check foreground application and do tasks accordingly

Question

I'm trying to create a service that will continuously check the foreground application, and when the certain app comes in to the foreground, do a task. When it exits the foreground, do another task. This should occur repeatedly until the user stops the service (I have service handling done already).

I don't know how to go about this. Here is how I'm checking for the current foreground application:

    /* Get all Tasks available (with limit set). */
    ActivityManager mgr = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
    List<ActivityManager.RunningTaskInfo> allTasks = mgr.getRunningTasks(showLimit);
    /* Loop through all tasks returned. */
    for (ActivityManager.RunningTaskInfo aTask : allTasks) 
    {                  
        Log.i("MyApp", "Task: " + aTask.baseActivity.getClassName()); 

        if (aTask.baseActivity.getClassName().equals("package")) 
            running=true;
    }

Then, I have a simple if/else that checks the status of running and preforms the tasks as required:

if(running =! true) {
    MainActivity defaults = new MainActivity();
    defaults.RunAsRoot(commandsdefault);
}

else {
    MainActivity defaults = new MainActivity();
    defaults.RunAsRoot(commands);
}

Now, that doesn't run continuously, it just does it once and stops. So, I put the entirety of my onCreate() inside a while():

boolean justrun = true;

while(doit = true) {
    //everything here: foreground checker, along with if/else
}

That didn't work either: Everything was just super slow and it ended up force closing, I'm assuming because it ate up all the resources it could.

How do I go about doing this? Main main goal seems to be pretty straightforward... I just want to get the foreground application package name, and just do commands as it changes.

EDIT: I added the following method to MyService:

public int serviceservice() {

    boolean running = true;
    int showLimit = 20;
    boolean doit = true;

    /* Get all Tasks available (with limit set). */
    ActivityManager mgr = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
    List<ActivityManager.RunningTaskInfo> allTasks = mgr.getRunningTasks(showLimit);
    /* Loop through all tasks returned. */
    for (ActivityManager.RunningTaskInfo aTask : allTasks) 
    {                  
        Log.i("MyApp", "Task: " + aTask.baseActivity.getClassName()); 

        if (aTask.baseActivity.getClassName().equals("package")) 
            running=true;
    }

    if(running =! true) {
        MainActivity defaults = new MainActivity();
        defaults.RunAsRoot(commandsdefault);


     }


    return START_STICKY;

}

And I called serviceservice(); in my OnCreate() and onStart(). It still only runs once. :/