Java 从三个侧面计算的角度仅显示90度或180度

这就是问题所在：编写一个程序，提示输入三角形边的长度，并报告三个角度

我为此编写了以下代码：

public static void main(String[] args) {
    
    Scanner console = new Scanner(System.in);
    
    System.out.print("Please input length of side A: ");
    int sideA = console.nextInt();
    System.out.print("Please input length of side B: ");
    int sideB = console.nextInt();
    System.out.print("Please input length of side C: ");
    int sideC = console.nextInt();
    System.out.println();
    System.out.println("The angle between A and B is: " + calculateAngle(sideA, sideB, sideC));
    System.out.println("The angle between B and C is: " + calculateAngle(sideB, sideC, sideA));
    System.out.println("The angle between C and A is: " + calculateAngle(sideC, sideA, sideB));     
}
    
    public static double calculateAngle(int a, int b, int c) {
        return Math.toDegrees(Math.acos((a * a + b * b - c * c) / (2 * a * b)));
    }

下面是我上面代码的示例输出：

Please input length of side A: 55
Please input length of side B: 22
Please input length of side C: 76

The angle between A and B is: 90.0
The angle between B and C is: 90.0
The angle between C and A is: 90.0

---

无论我为边输入什么值，我得到的唯一角度都是90度或180度，而不是可以根据余弦规则计算的实际正确角度。我的代码有什么问题？

只需将

Math.acos

中的计算转换为

double

：

return Math.toDegrees(Math.acos((double)(a * a + b * b - c * c) / (2 * a * b)));

正如您在注释中所看到的，当在多个

int

类型之间进行计算时，将使用

integer

算法，然后将其转换为

double

另外值得注意的是，

int

总是向下取整，意思是：

int i = 0.9999999;  // i = 0

---

根据文件，他们希望

acos

方法的参数为双值

所以像这样重新安排代码

  public static void main(String[] args) {

        Scanner console = new Scanner(System.in);

        System.out.print("Please input length of side A: ");
        double sideA = console.nextDouble();
                System.out.print("Please input length of side B: ");
        double sideB = console.nextDouble();
        System.out.print("Please input length of side C: ");
        double sideC = console.nextDouble();
        System.out.println();
        System.out.println("The angle between A and B is: " + calculateAngle(sideA, sideB, sideC));
        System.out.println("The angle between B and C is: " + calculateAngle(sideB, sideC, sideA));
        System.out.println("The angle between C and A is: " + calculateAngle(sideC, sideA, sideB));
    }

    public static double calculateAngle(double a, double b, double c) {
        return Math.toDegrees(Math.acos((a * a + b * b - c * c) / (2 * a * b)));
    }

---

为了澄清@Aplet123注释-整数除法意味着计算中的

acos

始终为零，即90度。将变量更改为

float

或

double

，或在计算中强制转换结果。谢谢！成功了！不客气。