Java - 在赋值时抛出 IllegalArgumentException

Question

我正在做一项 Java 作业，其中给了我一套指导方针，并要求我正确编写一个程序，根据性别、体重、高度和年龄，计算每周 1 - 3 天进行轻度运动/锻炼的人的每日卡路里需求。

作业的要点之一是学习异常的使用。我已经编写了代码，并且它可以正确编译。然而，当运行时，我总是抛出异常，即使在性别变量设置为 F、f、M 或 m 时也是如此。任何提示都是好的提示，但我想知道如何让这个程序启动。

澄清一下，所有的评论都来自老师，而所有的代码都来 self 。我使用这些注释作为我的代码的框架。另外，您会通过老师的评论注意到，我应该对calculateCalories() 中的其他参数抛出另一个IllegalArugmentException。我还没有这样做，因为我仍在努力使性别部分正确。

import java.util.*;

//add class javadoc comment here
public class CalorieCalculator {

public static final double LIGHT_ACTIVITY_FACTOR = 1.375;
public static final int MALE_BMR_CONSTANT = 66;
public static final int FEMALE_BMR_CONSTANT = 655;
public static final double MALE_WEIGHT_COEFFICIENT = 6.23;
public static final double FEMALE_WEIGHT_COEFFICIENT = 4.35;
public static final double MALE_HEIGHT_COEFFICIENT = 12.7;
public static final double FEMALE_HEIGHT_COEFFICIENT = 4.7;
public static final double MALE_AGE_COEFFICIENT = 6.8;
public static final double FEMALE_AGE_COEFFICIENT = 4.7;

//Prompt the user for gender (m,f,M,F), weight(lbs, double),
//height(inches, integer), and age(yrs, integer).
//You can assume the user will type in a number for weight
//and an integer for height and age - it is okay if the
//program crashes if they don't.
//Pass the user supplied values to the
//calculateCalories() method and output the returned daily calorie
//requirement (with descriptive text).

public static void main(String[] args) {
    Scanner console = new Scanner(System.in);

    System.out.print("Please enter your gender: ");
    String gender1 = console.next();
    System.out.print("Please enter your weight in pounds: ");
    double weight1 = console.nextDouble();
    System.out.print("Please enter your height in inches: ");
    int height1 = console.nextInt();
    System.out.print("Please enter your age in years: ");
    int age1 = console.nextInt();

    calculateCalories(gender1, weight1, height1, age1);


    System.out.println("Women:");
    System.out.println("Daily Calorie Requirement for Light Activity = " + (calculateCalories(gender1, weight1, height1, age1)));

}


//Throw an IllegalArgumentException if gender is not
//"f", "F", "m", or "M" or if any of the other parameters
//are not greater than 0. The exception message should
//explain the error.
//Use the formulas given below to calculate and return 
//the daily calorie requirement.

public static double calculateCalories(String gender, double weight, int height, int age) {
    if (gender.toLowerCase() != "m" || gender.toLowerCase() != "f") {
        throw new IllegalArgumentException("Please enter either M, F, m, or f");
    } else {

        if (gender == "f" || gender == "F") {
            double bmrFemale = (FEMALE_BMR_CONSTANT + (FEMALE_WEIGHT_COEFFICIENT * weight) + (FEMALE_HEIGHT_COEFFICIENT * height) - (FEMALE_AGE_COEFFICIENT * age));
            return LIGHT_ACTIVITY_FACTOR * bmrFemale; 
        } else {
            double bmrMale = (MALE_BMR_CONSTANT + (MALE_WEIGHT_COEFFICIENT * weight) + (MALE_HEIGHT_COEFFICIENT * height) - (MALE_AGE_COEFFICIENT * age));
            return LIGHT_ACTIVITY_FACTOR * bmrMale;
        }
    }

}

Answer 1

首先您需要在条件中使用 .equal 而不是 == ，第二个第一个条件应该是 && 而不是 ||

所以它看起来像这样

if (!gender.toLowerCase().equal("m") && !gender.toLowerCase().equal("f") {
        throw new IllegalArgumentException("Please enter either M, F, m, or f");