android studio的Handler简单实例

实现：EditText输入消息，通过按钮选择发送给主线程或者子线程；

以下有效果图、MainActivity.java代码和activity_main.xml代码

效果图：

MainActivity.java代码

package huan.san.handleroneapp;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    public static final String TAG = "MainActivity";
    private TextView mTextView1;
    private TextView mTextView2;
    private Button mButton1;
    private Button mButton2;
    private Handler1 mSubThreadHandler;
    private Handler2 mMainThreadHandler;
    private EditText mEditText;
    String sMessage;
    private int counter = 0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        init();
    }
    public void init() {
        mTextView1 = (TextView)findViewById(R.id.textView1);
        mTextView2 = (TextView)findViewById(R.id.textView2);
        mButton1 = (Button) findViewById(R.id.button1);
        mButton2 = (Button) findViewById(R.id.button2);
        mEditText = (EditText)findViewById(R.id.editTextTextPersonName) ;

        mButton1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                sMessage=mEditText.getText().toString();
                //主线程发送消息到子线程
                mSubThreadHandler = new Handler1(getMainLooper());
                Message message = new Message();
                message.obj = sMessage;
                mSubThreadHandler.sendMessage(message);
            }
        });
        mButton2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                sMessage=mEditText.getText().toString();
                //子线程发送消息到主线程
                mMainThreadHandler = new Handler2(getMainLooper());
                Message message = new Message();
                message.obj = sMessage;
                mMainThreadHandler.sendMessage(message);
            }
        });

        new Thread(){
            public void run(){
                Looper.prepare();
                //Looper.myLooper()获取当前线程的looper
                mSubThreadHandler = new Handler1(Looper.myLooper());
                Message message = new Message();
                message.obj = sMessage;
            };
        }.start();
    }
    
    public class Handler1 extends Handler{
        private Handler1(Looper looper){
            super(looper);
        }

        @Override
        public void handleMessage(@NonNull Message msg) {
            super.handleMessage(msg);
            //子线程消息显示
            mTextView2.setText("子线程收到：" + msg.obj);
        }
    }

    public class Handler2 extends Handler{
        private Handler2(Looper looper){
            super(looper);
        }

        @Override
        public void handleMessage(@NonNull Message msg) {
            super.handleMessage(msg);
            //主线程消息显示
            mTextView1.setText("主线程收到：" + msg.obj);

        }
    }
}

activity_main.xml代码