java中如何在代码中判断时间是否过了10秒

            long previous = 0L;
            ...
            {
                Calendar c = Calendar.getInstance();
                long now = c.getTimeInMillis();     //获取当前时间
                Log.d(TAG, "now-->" + now + ",,previous-->"+previous + ",,now - previous -->" + (now - previous));
                if(now - previous>= 5000){
                    // 两次点击时间差大于5秒
                    // do something
                    previous = now ;      //更新 previous
                    }
    //            previous = now ;
                }
              return true;