帧动画（时间的开始和暂停）

 ![在这里插入图片描述](https://img-blog.csdn.net/20181016113842853?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzMTI3Mjk4/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70)
 在进入程序时自动获取系统当前时间，后单击开始实现秒针的跳转，单击暂停按钮时停止秒针的跳转

layout代码

<?xml version="1.0" encoding="utf-8"?>
<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"
    tools:context="net.hw.dynamictime.MainActivity">

    <TextView
        android:id="@+id/tv_time"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="70sp"
        android:textColor="#ff0000" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btn_start"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="doStart"
            android:text="@string/start" />

        <Button
            android:id="@+id/btn_stop"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="doStop"
            android:text="@string/stop" />
            </LinearLayout>

</LinearLayout>

string代码

<resources>
    <string name="app_name">动态时间</string>
    <string name="start">开始</string>
    <string name="stop">停止</string>
</resources>

Java代码

package net.hw.dynamictime;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.TextView;

import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends Activity {
    private Thread thread;
    private Handler handler;
    private TextView tvTime;
    private SimpleDateFormat sdf;
    private boolean anniu;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //利用布局资源文件设置用户界面
        setContentView(R.layout.activity_main);
        //通过资源标识获得控件实例
        tvTime = findViewById(R.id.tv_time);
        //实例化简单日期格式化对象
        sdf = new SimpleDateFormat("hh:mm:ss");
        tvTime.setText(sdf.format(new Date()));
        //创建消息处理器，送的消息进行处理，更新主界面元素（标签）的内容
        handler = new Handler(){
            public void handleMessage(Message msg){
                super.handleMessage(msg);
                if(msg.what ==0x0001){
                    tvTime.setText(sdf.format(new Date()));

                }
            }
        };
        //创建线程，定时发送消息

    }
    public  void doStart(View view){
        anniu =true;
        thread = new Thread(new Runnable() {
            @Override
            public void run() {
                while(anniu){
                    //向主线程发送消息
                    handler.sendEmptyMessage(0x001);
                    //让线程睡眠500毫秒
                    try {
                        Thread.sleep(500);
                    }catch (InterruptedException e){
                        e.printStackTrace();
                    }
                }
            }
        });

        //启动线程
        thread.start();
    }
    public void doStop(View view){
        anniu = false;
        thread =null;
    }
    protected void onDestroy(){
        super.onDestroy();
        //销毁线程
        thread = null;


    }
}