android 如何判断程序是否在前台运行

protected static boolean isTopActivity(Activity activity){


        String packageName = "xxxxx";


        ActivityManager activityManager = (ActivityManager) activity.getSystemService(Context.ACTIVITY_SERVICE);


        List<RunningTaskInfo>  tasksInfo = activityManager.getRunningTasks(1);  


        if(tasksInfo.size() > 0){  


            System.out.println("---------------包名-----------"+tasksInfo.get(0).topActivity.getPackageName());


            //应用程序位于堆栈的顶层  


            if(packageName.equals(tasksInfo.get(0).topActivity.getPackageName())){  


                return true;  


            }  


        }  


        return false;


    }