TextView display system time of clock function with a second hand change

We start a thread that sends a message every second, and the time we update TextView in the message is ok.

First we put an TextView in the layout file to display the time, as shown below:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@android:color/white">
  <TextView
      android:id="@+id/mytime"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:gravity="center"
      android:textColor="@android:color/black"
      android:textSize="36sp"/>
</LinearLayout>

After that, we write a thread with an infinite loop and send a message every 1 second. Handler processes the displayed result:

public class TimeThread extends Thread {
        @Override
        public void run () {
            do {
                try {
                    Thread.sleep(1000);
                    Message msg = new Message();
                    msg.what = msgKey1;
                    mHandler.sendMessage(msg);
                }
                catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } while(true);
        }
    }

private Handler mHandler = new Handler() {
@Override
public void handleMessage (Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case msgKey1:
long sysTime = System.currentTimeMillis();
CharSequence sysTimeStr = DateFormat.format("hh:mm:ss", sysTime);
mTime.setText(sysTimeStr);
break;

default:
break;
}
}
};

Then we can start the thread in Activity's onCreate method, and we can see a digital clock:

public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.time);
         mTime = (TextView) findViewById(R.id.mytime);
         new TimeThread().start();
     }

The code of the entire Activity:

package com.fermax.test;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.text.format.DateFormat;
import android.widget.TextView;
public class TestActivity extends Activity {

    private static final int msgKey1 = 1;
    private TextView mTime;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.time);
        mTime = (TextView) findViewById(R.id.mytime);
        new TimeThread().start();
    }

    public class TimeThread extends Thread {
        @Override
        public void run () {
            do {
                try {
                    Thread.sleep(1000);
                    Message msg = new Message();
                    msg.what = msgKey1;
                    mHandler.sendMessage(msg);
                }
                catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } while(true);
        }
    }

    private Handler mHandler = new Handler() {
        @Override
        public void handleMessage (Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
                case msgKey1:
                    long sysTime = System.currentTimeMillis();
                    CharSequence sysTimeStr = DateFormat.format("hh:mm:ss", sysTime);
                    mTime.setText(sysTimeStr);
                    break;

                default:
                    break;
            }
        }
    };
}