TextView显示系统时间(时钟功能带秒针变化

我们开启一个线程，线程每隔一秒发送一次消息，我们在消息中更新textview上显示的时间就ok了。

首先我们在布局文件中放一个textview用来显示时间，如下所示：

<?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>

之后我们写一个线程，线程里面无限循环，每隔一秒发送一个消息,其中由handler来处理显示的结果：

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;
            }
        }
    };

之后我们可以在activity的oncreate方法中开启这个线程，这时我们可以看到一个数字时钟了：

public void oncreate(bundle savedinstancestate) {
         super.oncreate(savedinstancestate);
         setcontentview(r.layout.time);
         mtime = (textview) findviewbyid(r.id.mytime);
         new timethread().start();
     }

整个activity的代码：

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;
            }
        }
    };
}