<?xml version="1.0" encoding="utf-8"?> <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"   xmlns:app="http://schemas.android.com/apk/res-auto"   xmlns:tools="http://schemas.android.com/tools"   android:layout_width="match_parent"   android:layout_height="match_parent"   tools:context="com.amy.processbartest.MainActivity">    <!--水平進度條 -->   <ProgressBar     android:id="@+id/progressBar1"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:max="100"     style="@android:style/Widget.ProgressBar.Horizontal" />    <!-- 圓形進度條 -->   <ProgressBar     android:id="@+id/progressBar2"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     style="?android:attr/progressBarStyleLarge"/>  </android.support.constraint.ConstraintLayout> 

package com.amy.processbartest;  import android.os.Handler; import android.os.Message; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.ProgressBar; import android.widget.Toast;  import static android.R.attr.id;  public class MainActivity extends AppCompatActivity {    //定義水平進度條   private ProgressBar horizonP;   //定義圓形進度條   private ProgressBar circleP;   //完成進度   private int mProcessStatus = 0;   //聲明一個用于處理消息的Handler類的對象   private Handler mHandler;    /**    * 在主活動onCreate方法中，首先獲得水平進度條和圓形進度條，    * 然后通過匿名內部類實例化處理消息的Handler類的對象，并重寫其handlerMessage方法，    * 實現當好吃操作沒有完成時更新進度，否則設置進度條不顯示。    * @param savedInstanceState    */   @Override   protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);     horizonP = (ProgressBar) findViewById(R.id.progressBar1);     circleP = (ProgressBar) findViewById(R.id.progressBar2);     mHandler = new Handler(){       @Override       public void handleMessage(Message msg) {         if (msg.what == 0x111) {           horizonP.setProgress(mProcessStatus);//更新進度         } else {           Toast.makeText(MainActivity.this,"耗時操作已經完成",Toast.LENGTH_SHORT).show();           horizonP.setVisibility(View.GONE);           circleP.setVisibility(View.GONE);         }       }     };      //開個線程用語模擬耗時操作     new Thread(new Runnable() {       @Override       public void run() {         while (true) {           mProcessStatus = doWork();//獲取耗時操作完成的百分比           Message msg = new Message();           if (mProcessStatus<100) {             msg.what = 0x111;             mHandler.sendMessage(msg);//發送消息           } else {             msg.what = 0x110;             mHandler.sendMessage(msg);//發送消息             break;           }         }       }       //模擬一個耗時操作       private int doWork() {         mProcessStatus += Math.random()*10;//改變完成進度         try {           Thread.sleep(200);//每隔200毫秒進度改變一次         } catch (InterruptedException e) {           e.printStackTrace();         }         return mProcessStatus;//返回新的進度       }     }).start();//開啟一個新的線程    } }