Android入门之Handler的使用教程详解

<?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:id="@+id/RelativeLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    tools:context="org.mk.android.demohandlerwithanim.MainActivity" >
 
    <ImageView
        android:id="@+id/imgAnimation"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        />
 
</RelativeLayout>

package org.mk.android.demohandlerwithanim;
 
import androidx.appcompat.app.AppCompatActivity;
 
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.ImageView;
 
import java.util.Timer;
import java.util.TimerTask;
 
public class MainActivity extends AppCompatActivity {
    int imgids[] = new int[]{R.drawable.a_1, R.drawable.a_2, R.drawable.a_3, R.drawable.a_4, R.drawable.a_5, R.drawable.a_6, R.drawable.a_7, R.drawable.a_8};
    int imgstart = 0;
    ImageView imgAnimation;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        imgAnimation = findViewById(R.id.imgAnimation);
        Handler imgAnimationHandler = new ImgAnimatonHandler();
        new Timer().schedule(new TimerTask() {
            @Override
            public void run() {
                imgAnimationHandler.sendEmptyMessage(101);
            }
        }, 0, 100);
    }
 
    class ImgAnimatonHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            if (msg.what == 101) {
                imgAnimation.setImageResource(imgids[imgstart++ % 8]);
            }
        }
    }
}