用户输入失败 if 语句，我不知道为什么[关闭]

Question

我的程序正在根据用户的年龄、身高、体重和性别计算并打印用户的 BMR 值。

但是，在根据输入检查性别并直接跳转到 else 语句时，我的程序无法正常工作。 这是我目前的代码，我该如何解决？

import java.util.Scanner;
public class MaintainingWeight
{
    public static void main(String[] args) 
    {
        //Instance Variables
        int age, weight, inches; //weight in pounds, height inches
        double BMR;
        String gender;

        //Program Introduction Welcoming the user
        Scanner keyboard = new Scanner(System.in);
        System.out.println("Hello fellow user, this program will help determine \nyour BMR value and tell the amount of chocalate bars you will need");
        System.out.println("in order to maintain your body weight.");

        //Ask the User to input their age, weight and height
        System.out.println("Please enter your age.");
        age = keyboard.nextInt();

        System.out.println("Next enter your weight in pounds");
        weight = keyboard.nextInt();

        System.out.println("Now enter your height by inches\n (Reminder: to find your height in inches mutiply your height by feet to 12.000. (feet * 12.000))");
        inches = keyboard.nextInt();

        //Tell the user their gender then print their BMR Value
        System.out.println("Please enter your gender. Enter M as Men or W as women");
        gender = keyboard.nextLine();

        if (gender.equalsIgnoreCase("M"))
        {
            System.out.println("Your BMR value is: ");
        }
        else if (gender.equalsIgnoreCase("W"))
        {
            System.out.println("Your BMR Value is: ");
        }
        else
        {
            System.out.println();
        }

    }

    //Print to the user the amount of chocolate bars they need to consume to maintain their weight

}

Answer 1

好吧，我从来没有真正使用过java，如果我犯了任何编码错误，请原谅我......

if (gender.equalsIgnoreCase("M"))
{
    System.out.print("Your BMR value is: "); //Prints without a newline I assume
    System.out.print((66 + (13.8 * (weight * 0.454)) + (5 * (height * 2.54)) - (6.8 * age));
}
else if (gender.equalsIgnoreCase("W"))
{
    System.out.print("Your BMR value is: "); //Prints without a newline I assume
    System.out.print((655 + (9.6 * (weight * 0.454)) + (1.8 * (height * 2.54)) - (4.7 * age));
}
else
{
    System.out.println();
}

好的，问题是keyboard.nextLine() 在末尾添加了一个\n。两种修复方法：

if (gender.equalsIgnoreCase("M\n"))
{
}
else if (gender.equalsIgnoreCase("W\n"))
{
}

或

if (gender.contains("m") || gender.contains("M"))
{
}
else if (gender.contains("w") || gender.contains("W"))
{
}