package com.example.demo1;import android.annotation.SuppressLint;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.Menu;import android.view.MenuItem;import android.widget.TextView;public class MainActivity extends Activity {private TextView tv1;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);tv1 = (TextView) findViewById(R.id.textView1);handler.post(waitSendsRunnable);}//啟用一個HandlerHandler handler = new Handler() {@SuppressLint("HandlerLeak")public void handleMessage(Message msg) {super.handleMessage(msg);switch (msg.what) {case 0:Intent intent = new Intent(MainActivity.this, MainActivity2.class);startActivity(intent);break;case 1:tv1.setText("倒計時：" + index + "s");break;default:break;}}};// 倒計時五秒int index = 5;Runnable waitSendsRunnable = new Runnable() {public void run() {if (index > 0) {index--;try {Thread.sleep(1000);handler.sendEmptyMessage(1);} catch (InterruptedException e) {e.printStackTrace();}handler.post(waitSendsRunnable);} else {try {Thread.sleep(1000);handler.sendEmptyMessage(0);} catch (InterruptedException e) {e.printStackTrace();}}}};}