我需要使用 double 而不是 int 才能使我的结果正确。为什么？ （爪哇）

Question

今天我尝试用 Java 编写一个简单的程序，它可以给我输入的数字的平均值。

问题是，如果我使用 int added（如下所示），我得到的答案与使用 double added 时的答案不同。

代码：

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);

    }

}

结果：

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

当我使用 double 时，我得到了正确的答案：

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);

    }

}

当我使用 double added 而不是 int added 时的结果：

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: 3.5

为什么会发生这种情况，我应该怎么做才能避免它？ 对我来说，add 似乎是一个 int，因为我不加小数，但我加了整数。

提前谢谢你。

Answer 1

为了使 added/amount 返回非整数，added 或 amount 必须为 float 或 double 或强制转换为其中任何一个。

当两者都是int 时，进行整数除法，除法后结果仅转换为double，以便存储在您的double average 变量中。

Answer 2

两个元素都是整数的除法结果将是整数。至少其中一个必须是浮点数或双精度数才能使除法的结果为浮点数。