<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:gravity="center"
  android:orientation="vertical" >

  <TextView 
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="離結束時間為："/>

  <LinearLayout 
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:layout_marginTop="10dp"
    android:orientation="horizontal">

  <TextView
    android:id="@+id/tvtime1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:gravity="center"
    android:background="#3B3B3B"
    android:text="12"
    android:textColor="#FFFFFF"
    android:textSize="30sp" />

  <TextView
    android:id="@+id/tvtime2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:layout_marginLeft="10dp"
    android:gravity="center"
    android:text="12"
    android:textColor="#FFFFFF"
    android:background="#3B3B3B"
    android:textSize="30sp" />

  <TextView
    android:id="@+id/tvtime3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
     android:layout_marginLeft="10dp"
    android:gravity="center"
    android:background="#3B3B3B"
    android:textColor="#FFFFFF"
    android:text="13"
    android:textSize="30sp" />

  </LinearLayout>

</LinearLayout>

public class MainActivity extends Activity {
 private TextView tvtime1,tvtime2,tvtime3;
 private long time=400;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  tvtime1=(TextView)findViewById(R.id.tvtime1);
  tvtime2=(TextView) findViewById(R.id.tvtime2);
  tvtime3=(TextView) findViewById(R.id.tvtime3);
  handler.postDelayed(runnable, 1000); 
 }


 Handler handler = new Handler(); 
 Runnable runnable = new Runnable() { 
  @Override 
  public void run() { 
   time--; 
   String formatLongToTimeStr = formatLongToTimeStr(time);
   String[] split = formatLongToTimeStr.split("：");
   for (int i = 0; i < split.length; i++) {
    if(i==0){
     tvtime1.setText(split[0]+"小時");
    }
    if(i==1){
     tvtime2.setText(split[1]+"分鐘");
    }
    if(i==2){
     tvtime3.setText(split[2]+"秒");
    }

   }
   if(time>0){
    handler.postDelayed(this, 1000); 
   }
  } 
 }; 

 public String formatLongToTimeStr(Long l) {  
   int hour = 0;  
   int minute = 0;  
   int second = 0;  
   second = l.intValue() ;  
   if (second > 60) {   
   minute = second / 60;   //取整 
   second = second % 60;   //取余
   }  

   if (minute > 60) {   
   hour = minute / 60;   
   minute = minute % 60;  
   }  
   String strtime = hour+"："+minute+"："+second;
   return strtime; 

 }

}