如何使用 Java 中 if 语句中存在的用户输入？

Question

所以我想做的是要求用户输入他们的体重和考试 1 和 2 的分数，如果他们输入分数，则使用这些变量来计算当前分数。

但是，由于分数是由用户通过 if 语句内部的扫描器声明的，因此它不允许我从 if 语句外部使用这些变量。当我想计算 csEx1 和 csEx2 时，如何使用变量“examOneScore”和“examTwoScore”。

当我尝试使用它们时，它显示“局部变量 examOneScore 可能尚未初始化。”

import java.util.Scanner;

public class CurrentScore

{

    public static void main(String[] args) 

    {

       Scanner keyboard = new Scanner(System.in);

       System.out.printf("Weight of Exam 1: ");

       double weightExamOne = keyboard.nextDouble();

       System.out.printf("Weight of Exam 2: ");

       double weightExamTwo = keyboard.nextDouble();

       System.out.printf("Do you know your score of first exam? ");   

       String examOne = keyboard.nextLine();

       if(examOne.equalsIgnoreCase("yes") || examOne.equalsIgnoreCase("y"))  

       {

           System.out.printf("Your score? ");

           double examOneScore = keyboard.nextDouble();

       }

       System.out.printf("Do you know your score of secondexam? "); 

       String examTwo = keyboard.nextLine();

       if(answerTwo.equalsIgnoreCase("yes") || answerTwo.equalsIgnoreCase("y"))  

       {

           System.out.printf("Your score? ");

           double examTwoScore = keyboard.nextDouble();

       }

       double csEx1 = (weightExamOne * examOneScore);

       double csEx2 = (weightExamTwo * examTwoScore );

     }

}

Answer 1

您必须在 if 语句之外定义稍后要使用的变量：public static void main(String[] args){    Scanner keyboard = new Scanner(System.in);    System.out.printf("Weight of Exam 1: ");    double weightExamOne = keyboard.nextDouble();    System.out.printf("Weight of Exam 2: ");    double weightExamTwo = keyboard.nextDouble();    System.out.printf("Do you know your score of first exam? ");    String examOne = keyboard.nextLine();    double examOneScore = 1;    if(examOne.equalsIgnoreCase("yes") || examOne.equalsIgnoreCase("y"))    {        System.out.printf("Your score? ");        examOneScore = keyboard.nextDouble();    }    System.out.printf("Do you know your score of second exam? ");    String examTwo = keyboard.nextLine();    double examTwoScore = 1;    if(examTwo.equalsIgnoreCase("yes") || examTwo.equalsIgnoreCase("y"))    {        System.out.printf("Your score? ");        examTwoScore = keyboard.nextDouble();    }    double csEx1 = (weightExamOne * examOneScore);    double csEx2 = (weightExamTwo * examTwoScore );}我使用值 1 来定义它们，你必须自己寻找你想要在那里使用的