Java 使用get方法时获取NaN

我正在做一个体重指数计算器，为我的一个课程做一个节食计划。最初，我将两个变量作为公共静态变量，以从另一个类获取变量。我的体重指数计算器就是这样工作的

然后我发现我可以使用get方法获得更多分数。因此，我将前面的变量改为private，并使用get方法。但是当我运行这个程序时，当程序打印出保存BMI的变量时，我得到了NaN，这以前从未发生过

有人能帮忙吗

import java.util.Scanner;

public class Weight {
private Scanner input;
private String readInput;
private String userWeightIsPounds;
private String userWeightIsStones;

private Scanner input2;
public static double userWeight;

public Weight(){
    userWeightIsPounds = ("Pounds");
    userWeightIsStones = ("Stones");        
}

public void findOutUserWeightMessage(){
    System.out.println("Firstly Do you weigh yourself in pounds or stones?");
}

public void findOutUserWeight(){
    input = new Scanner (System.in);
    readInput = input.nextLine();
    if(readInput.equals(userWeightIsPounds)){
        System.out.println("Ok then, enter your weight in pounds please.");
    }
    if(readInput.equals(userWeightIsStones)){
        System.out.println("Ok enter your weight in stones please.");
    }   

    input2 = new Scanner (System.in);
    userWeight = input2.nextFloat();
    if (userWeight > 20){
        System.out.println("You've enetered your weight as " + userWeight + " lbs. I'll save that information for later.");
    }else{
        userWeight = userWeight * 14;
        System.out.println("I've converted your weight into pounds for you. You weigh " + userWeight + " lbs. I'll save that information for later.");  
    }
}

public double static getUserWeight(){
    return userWeight;
}

}

还有一个计算类的代码。忽略一些println，我试图找出我的变量发生了什么

public class BMI {

private double userHeightSqaured;
private double bmiMutiplier;
private double weightDivideHeight;
private double userBmi;
private double userWeightBmi;
private double userHeightBmi;



BMI(){
    bmiMutiplier = 703;
    userWeightBmi = Weight.getUserWeight();
    userHeightBmi = Height.getUserHeight();
}

public void startUpBmiMessage(){
    System.out.print("Lets start with your BMI then shall we? ");
}

public void calculateUserBmi(){
    System.out.println("userWeightBmi is " + userWeightBmi);
    System.out.println("userWeightBmi is " + userHeightSqaured);

    userHeightSqaured = userHeightBmi * userHeightBmi;
    System.out.println("userHeightSqaured is " + userHeightSqaured);
    weightDivideHeight = userWeightBmi/userHeightSqaured;
    System.out.println("weightDivideHeight is " + weightDivideHeight);

    userBmi = weightDivideHeight * bmiMutiplier;
    System.out.println("weightDivideHeight is " + weightDivideHeight);
    System.out.println("bmiMutiplier is " + bmiMutiplier);


}   

public void calculateUserBmiMessage(){

    System.out.println("Your bmi is " + userBmi);

}

---

}

听起来好像你在试图编写一个Java程序来执行一些计算，而计算的结果是NaN——你可以参考这个问题来了解有关NaN的一些信息

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至于在没有看到任何代码的情况下解决您的问题，并且假设您的计算在以前使用相同的输入时运行良好，听起来您使用getter从公共静态变量切换到私有变量可能会使一些变量未初始化，因此，它们的值默认为0-除以0是NaN的常见原因。

NaN的原因是以下语句：

    weightDivideHeight = userWeightBmi/userHeightSqaured;

零除以零。换句话说，userWeightBmi和userHeightSqaured在那个点上都是零

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根本的问题似乎是你没有意识到静态变量和实例变量之间的区别。当您应该/不应该使用这两种变量时。

请只看一个提示-关键字static不应该出现在代码中的任何地方，除了courseThanks removed static的主方法。但是eclipse一直告诉我要将修饰符更改为static@乔纳桑坎宁-你明白静态是什么意思吗？？？什么是静态变量？静态方法是什么？为什么不能从静态方法访问实例变量？回到你的课堂讲稿/课本/任何东西上，仔细阅读这些主题。