主线程才能操作UI界面

实现子线程处理主线程UI

MainActivity.java

package com.example.myhandler;import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;import android.annotation.SuppressLint;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.os.health.TimerStat;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;import java.util.Timer;
import java.util.TimerTask;/*** Handler 简单应用* 主线程才能处理界面UI* */
public class MainActivity extends AppCompatActivity {// 日志标记public  static final String TAG = MainActivity.class.getSimpleName();private TextView textView;private Button button,btnB;int data = 0;private Handler handler = new Handler(){@Overridepublic void handleMessage(@NonNull Message msg) {// 这里是主线 所以可以操作uiLog.e(TAG,"-----------handleMessage------------");Log.e(TAG,"当前线程--ThreadID---"+Thread.currentThread().getId()+"--ThreadName---"+Thread.currentThread().getName());Log.e(TAG,"主线程----ThreadID-"+getMainLooper().getThread().getId()+"----ThreadName"+getMainLooper().getThread().getName());switch (msg.what){case 0x11:data ++;textView.setText(String.valueOf(data));break;}}};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);Log.e(TAG, "-----------onCreate------------");Log.e(TAG, "当前线程--ThreadID---" + Thread.currentThread().getId() + "--ThreadName---" + Thread.currentThread().getName());Log.e(TAG, "主线程----ThreadID-" + getMainLooper().getThread().getId() + "----ThreadName" + getMainLooper().getThread().getName());textView = findViewById(R.id.tv_test);button = findViewById(R.id.btn_start);btnB = findViewById(R.id.btn_startB);//发消息button.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {Log.e(TAG, "当前线程onClick--ThreadID---" + Thread.currentThread().getId() + "--ThreadName---" + Thread.currentThread().getName());//每隔一秒发个消息Timer timer = new Timer();timer.schedule(new TimerTask() {@Overridepublic void run() {// 这里面是子线程 不可操作ui  会报错
//                        textView.setText("error");Log.e(TAG, "-----------run------------");Log.e(TAG, "当前线程--ThreadID---" + Thread.currentThread().getId() + "--ThreadName---" + Thread.currentThread().getName());Log.e(TAG, "主线程----ThreadID-" + getMainLooper().getThread().getId() + "----ThreadName" + getMainLooper().getThread().getName());//                        handler.sendEmptyMessage(0x11);handler.sendEmptyMessage(0x222);}}, 0, 1000);}});//子线程处理主线的UIbtnB.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {new Thread(){@Overridepublic void run() {Log.e(TAG, "-----------Thread--run------------");Log.e(TAG, "当前线程--ThreadID---" + Thread.currentThread().getId() + "--ThreadName---" + Thread.currentThread().getName());Looper.prepare();//子线程中的 handlehandler = new Handler(){@Overridepublic void handleMessage(@NonNull Message msg) {Log.e(TAG, "-----------Thread----handleMessage----------");Log.e(TAG, "当前线程--ThreadID---" + Thread.currentThread().getId() + "--ThreadName---" + Thread.currentThread().getName());if(msg.what == 0x222){data++;// 修改主线程中的UIMainActivity.this.runOnUiThread(new Runnable() {@Overridepublic void run() {Log.e(TAG, "-----------Thread----runOnUiThread----------");Log.e(TAG, "当前线程--ThreadID---" + Thread.currentThread().getId() + "--ThreadName---" + Thread.currentThread().getName());//主线程textView.setText(data+"");}});}}};Looper.loop();}}.start();}});}
}

 activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"android:orientation="vertical"tools:context=".MainActivity"><TextViewandroid:id="@+id/tv_test"android:textSize="24sp"android:layout_width="match_parent"android:layout_height="wrap_content"/><Buttonandroid:id="@+id/btn_start"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="开始执行"/><Buttonandroid:id="@+id/btn_startB"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="子线程处理主线"/>
</LinearLayout>