我需要使用double而不是int，因爲我的結果是正確的。爲什麼？ （Java）

Question

今天我試着用Java編寫一個簡單的程序，它給了我輸入的數字的平均值。

問題是，如果我使用int添加（如下圖所示），我沒有得到相同的答案，因爲當我使用雙添加。

代碼：

public class Main { 

    public static void main(String[] args) { 

     int amount; 
     int number; 
     int added = 0; 
     double average; 

     Scanner input = new Scanner(System.in); 

     System.out.println("This program calculates the average of the numbers entered by you."); 
     System.out.println("How many numbers do you want to enter?"); 
     amount = input.nextInt(); 

     for(int i=1; i<=amount; i++){ 
      System.out.println("Enter a number:"); 
      number = input.nextInt(); 
      added = added + number; 
     } 

     average = added/amount; 
     System.out.println("The average of the numbers entered is: " + average); 

    } 

} 

結果：

This program calculates the average of the numbers entered by you. 
How many numbers do you want to enter? 
6 
Enter a number: 
3 
Enter a number: 
2 
Enter a number: 
4 
Enter a number: 
1 
Enter a number: 
6 
Enter a number: 
5 
The average of the numbers entered is: 3.0 

當我使用雙，我得到正確的答案：

public class Main { 

    public static void main(String[] args) { 

     int amount; 
     int number; 
     double added = 0; 
     double average; 

     Scanner input = new Scanner(System.in); 

     System.out.println("This program calculates the average of the numbers entered by you."); 
     System.out.println("How many numbers do you want to enter?"); 
     amount = input.nextInt(); 

     for(int i=1; i<=amount; i++){ 
      System.out.println("Enter a number:"); 
      number = input.nextInt(); 
      added = added + number; 
     } 

     average = added/amount; 
     System.out.println("The average of the numbers entered is: " + average); 

    } 

} 

結果，當我使用雙增加，而不是INT加入：

This program calculates the average of the numbers entered by you. 
How many numbers do you want to enter? 
6 
Enter a number: 
3 
Enter a number: 
2 
Enter a number: 
4 
Enter a number: 
1 
Enter a number: 
6 
Enter a number: 
5 
The average of the numbers entered is: 3.5 

爲什麼會發生這種情況，我應該怎麼做才能避免它？ 對我來說，似乎添加可能是一個整數，因爲我不加小數，但我加起來整數。

預先感謝您。

Answer 1

爲了added/amount返回一個非整數，在added或amount必須float或double或轉換爲其中一方。

當二者都int，一個整數除法發生並且因此僅轉換爲double分割之後，以被存儲在你的doubleaverage變量。

Answer 2

其中均爲元素爲整數的除法結果將爲整數。至少其中一個需要浮點或浮點數的結果爲浮點數。