Android之Handler 最简单的代码实现Handler-蒲公英云

Android之Handler 最简单的代码实现Handler

快来打我* 2022-02-14 05:40 385阅读 0赞

首先先写一个简单的布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity">
    <Button
        android:id="@+id/btn_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="Button"/>
    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="Hello World!" />
</LinearLayout>

之后就是编写主代码了

package com.example.handlepro;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        final TextView textView;
        super.onCreate (savedInstanceState);
        setContentView (R.layout.activity_main);
        textView = findViewById (R.id.textView);
         final Handler handler = new Handler (){   //创建Handler
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage (msg);
                Log.d (TAG, "handleMessage: "+msg.what);
                if(msg.what == 1001){
                    textView.setText ("Fuck");
                }
            }
        };
         findViewById (R.id.btn_1).setOnClickListener (new View.OnClickListener () {
             @Override
             public void onClick(View v) {
                new Thread (new Runnable () {       //子线程
                    @Override
                    public void run() {
                        handler.sendEmptyMessage (1001);
                    }
                }).start ();   //启动线程
             }
         });
    }
}

主线程接收到子线程的消息，然后去处理，就可以实现文本的改变了

其实最简单简洁的代码是这样的

package com.example.handlepro;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        final TextView textView;
        super.onCreate (savedInstanceState);
        setContentView (R.layout.activity_main);
         Handler handler = new Handler (){
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage (msg);
                Log.d (TAG, "handleMessage: "+msg.what);
            }
        };
         textView = findViewById (R.id.textView);
         findViewById (R.id.btn_1).setOnClickListener (new View.OnClickListener () {
             @Override
             public void onClick(View v) {
                new Thread (new Runnable () {
                    @Override
                    public void run() {
                        textView.setText ("Fuck");
                    }
                }).start ();
             }
         });
    }
}