安卓获取当前系统栈顶的activity

最近经常要判断当前第一个activity是哪一个activity，对此做一个记录，下面贴上代码
  

private boolean isTopActivity(String className) {

    ActivityManager manager = (ActivityManager)                         
    mContext.getSystemService(Context.ACTIVITY_SERVICE);

    ComponentName cn = manager.getRunningTasks(1).get(0).topActivity;

    String topActivityName = cn.getClassName(); Log.i(TAG,"topActivityName:" + topActivityName);

    return topActivityName.equals(className);

}