android 计数器延时问题

我的计数器刚进去是00:00:00 现在进去后过了2-3秒才变成00:00:01，这是怎么回事。

XML

 <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:id="@+id/timeout"
                android:text="00:00:00"
                android:enabled="true" />

java

  tock_on.setOnClickListener(new View.OnClickListener() {
                public void onClick(View arg0) {
                    stepTimeHandler = new Handler();
                    startTime = System.currentTimeMillis();//获取时间
                    mTicker = new Runnable() {
                        public void run() {
                            String content = showTimeCount(System.currentTimeMillis() - startTime);
                            timeout.setText(content);
                            long now = SystemClock.uptimeMillis();
                            long next = now + (1000 - now % 1000);
                            stepTimeHandler.postAtTime(mTicker, next);
                        }
                    };
                    //启动计时线程，定时更新
                    mTicker.run();
                }
            });
public String showTimeCount(long time) {
                 if(time >= 360000000){
                         return "00:00:00";
                     }
                 String timeCount = "";
                long hourc = time/3600000;
                 String hour = "0" + hourc;
                 hour = hour.substring(hour.length()-2, hour.length());

                 long minuec = (time-hourc*3600000)/(60000);
                 String minue = "0" + minuec;
                 minue = minue.substring(minue.length()-2, minue.length());

                 long secc = (time-hourc*3600000-minuec*60000)/1000;
                 String sec = "0" + secc;
                 sec = sec.substring(sec.length()-2, sec.length());
                 timeCount = hour + ":" + minue + ":" + sec;
                 return timeCount;
    }

调用系统时间不对，重新换一种设计方法

你可以把你的代码贴出来一起看看