package com.example.handle_01;import android.os.Handler;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.widget.ImageView;import android.widget.TextView;public class MainActivity extends AppCompatActivity {  private TextView textView;  private Handler handler = new Handler();  private ImageView imageView;  private int[]images = {      R.mipmap.image1,R.mipmap.image2  };  private int index;  private MyRunnable myRunnable = new MyRunnable();  class MyRunnable implements Runnable{    @Override    public void run() {      index++;      index = index%2;      imageView.setImageResource(images[index]);      handler.postDelayed(myRunnable,1000);    }  }  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    textView = (TextView) findViewById(R.id.textView);    imageView = (ImageView) findViewById(R.id.imageView);    handler.post(myRunnable);    /*    new Thread(){      public void run(){        try {          Thread.sleep(1000);          //post方法xiugai UI          handler.post(new Runnable() {            @Override            public void run() {              //在UI線程中執行              textView.setText("update thread");            }          });          // textView.setText("update thread");        } catch (InterruptedException e) {          e.printStackTrace();        }      }    }.start();    */  }}

<?xml version="1.0" encoding="utf-8"?><RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"  android:paddingLeft="@dimen/activity_horizontal_margin"  android:paddingRight="@dimen/activity_horizontal_margin"  android:paddingTop="@dimen/activity_vertical_margin"  tools:context="com.example.handle_01.MainActivity">  <TextView    android:id="@+id/textView"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="Hello World!" />  <ImageView    android:src="@mipmap/ic_launcher"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:id="@+id/imageView"    android:layout_centerInParent="true" /></RelativeLayout>