Android——使用handler实现轮播图
16lz
2021-01-26
xml文件
<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <Button android:id="@+id/change" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" android:layout_marginTop="8dp" android:text="Button" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <TextView android:id="@+id/text" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" android:layout_marginTop="8dp" android:text="TextView" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/change" /> <ImageView android:id="@+id/imageView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" android:layout_marginTop="8dp" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/text" tools:srcCompat="@tools:sample/avatars[10]" /></android.support.constraint.ConstraintLayout>MainActivity.java
package com.example.threadtest;import android.os.Handler;import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.ImageView;import android.widget.TextView;import static java.lang.Thread.sleep;public class MainActivity extends AppCompatActivity { public static final int UPDATA = 1; private TextView textView; private Button button; private Handler hander; private ImageView imageView; private String[] strings={"1","2","3"}; private int[] imageViews={R.mipmap.a,R.mipmap.b,R.mipmap.c}; int index=0; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); textView=findViewById(R.id.text); button=findViewById(R.id.change); imageView=findViewById(R.id.imageView); hander=new Handler(){ @Override public void handleMessage(Message msg) { switch (msg.what){ case UPDATA: index=index%3; textView.setText(strings[index]); imageView.setImageResource(imageViews[index]); index++; } } }; button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { final Thread thread= new Thread(new Runnable() { @Override public void run() { while (true) { Message message = new Message(); message.what = UPDATA; hander.sendMessage(message); try { sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } } }); thread.start(); } }); }}- Message是线程之间传递的消息，携带少量信息，int类型的what，arg1,arg2和object类型的obj。
- Hander是发送以及处理消息的，发送消息使用sendMessage(),最终处理消息在handleMessage()中。
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