<&#63;xml version="1.0" encoding="utf-8"&#63;>
<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:orientation="vertical">

 <LinearLayout
 android:layout_width="match_parent"
 android:layout_height="110dp"
 android:layout_marginHorizontal="20dp"
 android:orientation="horizontal">

 <TextView
  android:layout_width="150dp"
  android:layout_height="80dp"
  android:layout_marginTop="15dp"
  android:background="@drawable/shape"
  android:gravity="center_horizontal"
  android:text="鬧鐘"
  android:textAlignment="center"
  android:textSize="50sp"></TextView>

 <EditText
  android:autofillHints="true"
  android:hint="10:10:10"
  android:id="@+id/num"
  android:layout_width="match_parent"
  android:layout_height="80dp"
  android:layout_marginLeft="15dp"
  android:layout_marginTop="5dp"
  android:background="@drawable/shape"
  android:gravity="center"
  android:inputType="time"
  android:textSize="35sp"></EditText>
 </LinearLayout>

 <Button
 android:id="@+id/btnStart"
 android:layout_width="match_parent"
 android:layout_height="80dp"
 android:layout_marginHorizontal="20dp"
 android:layout_marginTop="15dp"
 android:background="@drawable/shape"
 android:text="開始"
 android:textSize="50sp"></Button>

 <TextView
 android:id="@+id/text1"
 android:layout_width="match_parent"
 android:layout_height="300dp"
 android:layout_margin="20dp"
 android:background="@drawable/shape"
 android:gravity="center"
 android:text="倒計時"
 android:textSize="100sp"></TextView>
</LinearLayout>

package com.example.clock;
import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.util.Log;
import android.widget.EditText;
public class MyService extends Service {
 public MyService() {
 }
 @Override
 public IBinder onBind(Intent intent) {
 return new MyBinder(); //必須實現的方法，用于活動與服務之間的綁定
 }
 public class MyBinder extends Binder {
 MyHandler handler;
 public MyService getMyService() {
  return MyService.this;
 }
 public MyHandler getHandler() {
  handler=new MyHandler();//初始化一個消息對象
  return handler; //返回該消息對象
 }
 }
 public class MyHandler extends Handler {
 public String[] nums;
 public String str;
 public String str1;
 public void handleMessage(Message msg) {
  str1= String.valueOf(msg.obj); //獲取MainActivity中傳遞的消息
  Log.d("渣", str1);
  new Thread(new Runnable() {
  @Override
  public void run() { //開啟一個線程
   nums=str1.split(":"); //將獲取到的字符串拆分成數組
   //將字符串中的時間轉換成秒
   int time1=Integer.parseInt(nums[2])+60*60*Integer.parseInt(nums[1])+60*Integer.parseInt(nums[1]);
   for(int time = time1;time>=0;time--){ //通過for循環對對時間進行循環
   if(time==0){ //如果時間倒計時到0，則顯示（時間到）字樣
    MainActivity.textView.setText("時間到!");
   }
   try { //將time秒重新轉換成時間字符串
    int hour = 0;
    int minutes = 0;
    int sencond = 0;
    int temp = time % 3600;
    if (time > 3600) {
    hour = time / 3600;
    if (temp != 0) {
     if (temp > 60) {
     minutes = temp / 60;
     if (temp % 60 != 0) {
      sencond = temp % 60;
     }
     } else {
     sencond = temp;
     }
    }
    } else {
    minutes = time / 60;
    if (time % 60 != 0) {
     sencond = time % 60;
    }
    }
    str=(hour<10&#63;("0"+hour):hour) + ":" + (minutes<10&#63;("0"+minutes):minutes)
     + ":" + (sencond<10&#63;("0"+sencond):sencond);
    MainActivity.num.setText(str); //及時更新EditText的值
    Thread.sleep(1000); //線程休眠1秒
   } catch (Exception e) {
    e.printStackTrace();
   }
   }
  }
  }).start();
 }
 }

 @Override
 public void onDestroy() {
 super.onDestroy();
 }
}

package com.example.clock;

import androidx.appcompat.app.AppCompatActivity;

import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Binder;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
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 {
 MyService.MyBinder myBinder;
 public static EditText num;
 int flag = 0;
 String str;
 Intent intent;
 public static TextView textView;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 textView=findViewById(R.id.text1);
 final Button btnStart = (Button) findViewById(R.id.btnStart);
 num = (EditText) findViewById(R.id.num);
 btnStart.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  if (flag == 0) {
   if (num.getText().length() < 1) { //如果未輸入數值，則獲取默認填充值（Hint）
   str = String.valueOf(num.getHint());
   }else {
   str=num.getText().toString(); //獲取輸入的值
   }
   flag = 1; //用于判斷按鈕狀態
   btnStart.setText("暫停");
   num.setEnabled(false); //將EditText設置為不可編輯
   intent = new Intent(MainActivity.this, MyService.class); //創建啟動Service的Intent對象
   bindService(intent, conn, BIND_AUTO_CREATE); //綁定指定Service
   Log.d("time", String.valueOf(str));
  } else {
   flag = 0;
   btnStart.setText("開始");
   myBinder.getMyService().onDestroy();
  }
  }
 });
 }
 ServiceConnection conn = new ServiceConnection() {
 @Override
 public void onServiceConnected(ComponentName name, IBinder service) {//設置與服務進行通信
  myBinder = (MyService.MyBinder) service; //獲取服務中的MyBinder對象
  Message message = new Message(); //創建消息對象
  message.obj = str; //傳遞參數，str是獲取到的值
  MyService.MyHandler handler = myBinder.getHandler(); //獲取MyService中的Handler對象
  handler.sendMessage(message); //通過Handler對象發送消息
 }

 @Override
 public void onServiceDisconnected(ComponentName name) {

 }
 };
}