Find back stack activities in an android application?

The code below can be used to extract all the tasks and the top activity within each task in the back stack


ActivityManager m = (ActivityManager) ctx.getSystemService( ctx.ACTIVITY_SERVICE );
List<RunningTaskInfo> runningTaskInfoList =  m.getRunningTasks(10);
Iterator<RunningTaskInfo> itr = runningTaskInfoList.iterator();
while(itr.hasNext()){
    RunningTaskInfo runningTaskInfo = (RunningTaskInfo)itr.next();
    int id = runningTaskInfo.id;
    CharSequence desc= runningTaskInfo.description;
    int numOfActivities = runningTaskInfo.numActivities;
    String topActivity = runningTaskInfo.topActivity.getShortClassName();
}