실행중인 Task별 Activity 보기..

1. AndroidManifest.xml에 Permission 처리
    -  <uses-permission android:name="android.permission.GET_TASKS"/>

2. 다음과 같이 코딩을 하세요..
  
    // ActivityManager를 얻고..
   ActivityManager actMgr = (ActivityManager)AppPinScreenLockActivity.this.getSystemService(Activity.ACTIVITY_SERVICE);
   
   
    List<RunningTaskInfo> info = actMgr.getRunningTasks(7);
   
    for (Iterator<RunningTaskInfo> iterator = info.iterator(); iterator.hasNext();)  {
         RunningTaskInfo runningTaskInfo = (RunningTaskInfo) iterator.next();
         Log.d(TAG, "" + runningTaskInfo.topActivity.getClassName());
    }