BMI计算器NaN输出

Question

我最近刚刚开始按照我的教授的要求使用记事本使用Java进行编码，并且需要创建一个BMI计算器（我以前在C ++中已经做过）。但是，尽管我的类和驱动程序都进行了编译-并且我没有看到任何错误-，但程序输出在应返回浮点数时返回了“ NaN”。谁能让我知道我哪里出了问题？该类的代码：

import java.util.Scanner;
public class BMICalculator
{
    Scanner input = new Scanner(System.in);
    float weight;
    float height;
    float bmi;
    public float calculateBMI()
    {
        bmi = (weight / (height * height)) * 703;
    }
    public void setWeight(float aWeight)
    {
        weight = aWeight;
    }
    public void setHeight(float aHeight)
    {
        height = aHeight;
    }
    public float getWeight()
    {
        return weight;
    }
    public float getHeight()
    {
        return height;
    }
    public float getBMI()
    {
        return bmi;
    }
    public void ask()
    {
        System.out.print("Enter a weight in pounds: ");
        weight = input.nextFloat();
        System.out.print("Enter a height in inches: ");
        height = input.nextFloat();
        calculateBMI();
    }
    public void show()
    {
        System.out.println();
        System.out.println("Body Mass Index: " + bmi);
        if (bmi <= 0)
        {
            System.out.println("Something went wrong...");
        }
        else if (bmi >= 1.0 && bmi < 18.5)
        {
            System.out.println("Underweight.");
        }
        else if (bmi >= 18.5 && bmi < 25.0)
        {
            System.out.println("Normal weight.");
        }
        else if (bmi >= 25.0 && bmi < 30.0)
        {
            System.out.println("Overweight.");
        }
        else if (bmi >= 30.0)
        {
            System.out.println("Obese.");
        }
    }
}

驱动程序主代码：

public class BMICalculatorDriver
{
    public static void main(String [] args)
    {
        BMICalculator userBMI = new BMICalculator();
        userBMI.ask();
        userBMI.show();
    }
}