android:定时器

android定时器

package com.smartdot.handlerapi;

import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

import java.util.Timer;
import java.util.TimerTask;

public class MainActivity extends AppCompatActivity {
    Timer timer;
    TimerTask task ;
    TextView tv_text;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv_text = (TextView) findViewById(R.id.tv_text);
        //定时器初始化
        timer = new Timer();
        //定时任务，不可重复使用
        task = new TimerTask() {
            @Override
            public void run() {
                //不管在哪个位置runOnUiThread方法都运行在主线程中
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        tv_text.setText(Math.random() + "");
                    }
                });
            }
        };
        //timer.schedule(task,5000);//五秒后执行方法
        timer.schedule(task,3000,1000);//三秒后没隔1秒执行一次
        Handler handler = new Handler();
        //定时器，两秒钟之后执行run方法
        handler.postAtTime(new Runnable() {
            @Override
            public void run() {
                System.out.println("我是五秒钟之后执行的。");

            }
        },5000);





    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        task.cancel();
        timer.cancel();
    }
}