handler.java

package com.example.androidthreadtest;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;

/**
 * 作者： andli
 * 时间： 2017/11/1 18:17
 * 描述： 通过Handler改变TextView的值
 */
public class MainActivity extends Activity implements OnClickListener {


    private TextView text;

    private Button changeText;

    public static final int UPDATE_TEXT = 1;

    private Handler handler = new Handler() {

        public void handleMessage(Message msg) {
            switch (msg.what) {

                // 处理消息
                case UPDATE_TEXT:
                    text.setText("Handler异步操作");
                    break;

                default:
                    break;
            }
        }

    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        text = (TextView) findViewById(R.id.text);
        changeText = (Button) findViewById(R.id.change_text);
        changeText.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.change_text:

                // 子线程
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        Message message = new Message();
                        message.what = UPDATE_TEXT;
                        handler.sendMessage(message); // 发送消息
                    }
                }).start();

                break;
            default:
                break;
        }
    }

}