package com.firstapp.foo.firstapp;import android.os.Handler;import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log;import android.widget.Button;import android.widget.ProgressBar;import android.widget.TextView;import java.util.Date;public class ThreadDemoActivity extends AppCompatActivity {    private static final String TAG = "foo";    private ProgressBar bar;    private Button btnStartThread;    private TextView tvMsg;    private Handler handler;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        handler = new MyHandler();        setContentView(R.layout.activity_thread_demo);        bar = (ProgressBar)findViewById(R.id.progressBar);        btnStartThread = (Button)findViewById(R.id.btnStartThread);        tvMsg = (TextView)findViewById(R.id.tvMsg);        btnStartThread.setOnClickListener(v -> {            new Thread(()->{                for (int i=0; i< 100; i++){                    bar.setProgress(i);                    try {                        Thread.sleep(30);                    } catch (InterruptedException e) {                        e.printStackTrace();                    }                    Log.i(TAG, "Thread Info:" + i);                }                Bundle bundle = new Bundle();                bundle.putString("msg","你好");                // other ...                Message message = handler.obtainMessage();                message.what = 2;                message.setData(bundle);                handler.sendMessage(message);                /* 若消息除消息码外,无附加参数，则下面一句更简便 */                //handler.sendEmptyMessage(2);            }).start();        });    }    class MyHandler extends  Handler {        @Override        public void handleMessage(Message msg) {            switch (msg.what){                case 2:                    Bundle data = msg.getData();                    String txt = data.getString("msg");                    tvMsg.setText(txt + ", 线程完成:" + new Date().toString() );                    break;            }        }    }}