progressDialog和子线程模拟显示拷贝进度

package com.example.wang.myapplication;

import android.app.ProgressDialog;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class ZuoyeActivity4 extends AppCompatActivity {

    Button bt_1;
    Button bt_2;

    TextView tv_1;

    Handler h=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);

            if (msg.what==1)
            {
                tv_1.setText("拷贝完成");
            }
            else if(msg.what==2)
            {
                tv_1.setText("");
            }
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_zuoye4);

        bt_1=(Button)findViewById(R.id.bt_1);
        bt_1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                final ProgressDialog progressDialog=new ProgressDialog(ZuoyeActivity4.this);

                progressDialog.setTitle("拷贝进度");
                progressDialog.setMessage("拷贝中...");
                progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
                progressDialog.show();

                new Thread(){
                    @Override
                    public void run() {

                        for (int i=0;i<=100;i++)
                        {
                            progressDialog.setProgress(i);

                            try {

                                Thread.sleep(100);
                            }
                            catch (Exception e)
                            {
                                e.printStackTrace();
                            }
                        }
                        progressDialog.dismiss();

                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(ZuoyeActivity4.this, "拷贝完成", Toast.LENGTH_SHORT).show();
                            }
                        });
                    }
                }.start();
            }
        });

        tv_1=(TextView)findViewById(R.id.tv_1);
        bt_2=(Button)findViewById(R.id.bt_2);

        bt_2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //常规方法跨线程访问组件
//                runOnUiThread(new Runnable() {
//                    @Override
//                    public void run() {
//                        tv_1.setText("");
//                    }
//                });

                h.sendEmptyMessage(2);
                final ProgressDialog  progressdialog=new ProgressDialog(ZuoyeActivity4.this);

                progressdialog.setTitle("拷贝进度");

                progressdialog.setMessage("请稍后....");

                progressdialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);

                progressdialog.show();

                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        for (int i=0;i<100;i++)
                        {
                            progressdialog.setProgress(i);

                            try{
                                Thread.sleep(100);}
                            catch (Exception e)
                            {
                                e.printStackTrace();
                            }
                        }

                        progressdialog.dismiss();

                        h.sendEmptyMessage(1);
                    }
                }).start();

            }
        });

    }
}

<?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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.wang.myapplication.ZuoyeActivity4"
    android:orientation="vertical">

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="开始拷贝文件--普通方式"
        android:id="@+id/bt_1"/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="开始拷贝文件--消息机制"
        android:id="@+id/bt_2"/>

    <TextView
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:background="#ccc"
        android:gravity="center"
        android:textSize="16sp"
        android:id="@+id/tv_1"/>

</LinearLayout>

1.普通方式显示结果

2-消息机制结果