Android利用Timer实现倒计时效果小demo

今天闲来无聊，就写个倒计时吧！
1. 布局，两个button

id="@+id/bt_get"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="开始"/>
id="@+id/bt_post"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="结束"/>

实现代码

 public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private Button bt_get,bt_post;
    private String TAG="MainActivity";
    // 拿到okHttpClient对象
    private OkHttpClient okHttpClient=new OkHttpClient();
    private Timer timer5;
    private int num=11;
    private boolean flag=false;
    private Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what){
                case 0:
                    if(num<=0) {
                        flag=false;
                    }
                    else {
                        num--;
                        Log.i(TAG, "handleMessage: "+num);
                    }
                    break;
            }
            super.handleMessage(msg);
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        rollMethod();
    }
    public void initView(){
        bt_post= (Button) findViewById(R.id.bt_post);
        bt_get= (Button) findViewById(R.id.bt_get);
        bt_post.setOnClickListener(this);
        bt_get.setOnClickListener(this);
    }
    @Override
    public void onClick(View v) {

        switch (v.getId()){
            case R.id.bt_get:
                //getRequest();
                Log.i(TAG, "onClick: 开始");
                flag=true;
                num=11;
                break;
            case R.id.bt_post:
                //postRequest();
                Log.i(TAG, "onClick: 结束");
                flag=false;
                break;
        }
    }
    public void rollMethod(){
        if(null==timer5){
            timer5=new Timer();
        }
        timer5.schedule(new TimerTask() {
            @Override
            public void run() {
                if(flag){
                    handler.sendEmptyMessage(0);
                }
            }
        },3000,3000);
    }
}