java - If 语句错误地评估字符串

Question

编译此程序时，在给出正确答案时，每个 case 内的 if 语句始终计算为 false(错误)，代码如下:

import java.util.Scanner;

class GameStarts {
  public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   String ret;
   byte qnum;
   String ans;

   String correct = "Awesomely correct!";
   String wrong = "Darn it! Almost got it!";

   System.out.println("Do you think you know your stuff?");
   ret = sc.nextLine();

   if (ret.equals("yes") || ret.equals("Yes"))
   {
    System.out.println("Well, then let's test what you know! Choose a number from 1 to 5!");
    qnum = sc.nextByte();
      switch (qnum)
      {
     case 1:
    System.out.println("In what year did the French Revolution start?");
    ans = sc.nextLine();
    sc.nextLine();
      if (ans.equals("1789") || ans.equalsIgnoreCase("seventeen eighty nine"))
      {System.out.println(correct);}
      else
      {System.out.println(wrong);}

     break;

    case 2:
    System.out.println("How many protons does a sodium atom have?");
    ans = sc.nextLine();
    sc.nextLine();
      if (ans.equals("11") || ans.equalsIgnoreCase("eleven"))
      {System.out.println(correct);}
      else
      {System.out.println(wrong);}

     break;

    case 3:
    System.out.println("What is 2^6*0.5-12?");
    ans = sc.nextLine();
    sc.nextLine();
      if (ans.equals("20") || ans.equalsIgnoreCase("twenty"))
      {System.out.println(correct);}
      else
      {System.out.println(wrong);}

     break;

    case 4:
    System.out.println("Which is the lowest numbered element in the periodic table?");
    ans = sc.nextLine();
    sc.nextLine();
      if (ans.equalsIgnoreCase("hydrogen"))
      {System.out.println(correct);}
      else
      {System.out.println(wrong);}

     break;

    case 5:
    System.out.println("Which is the unit that measures Coulombs per second?");
    ans = sc.nextLine();
    sc.nextLine();
      if (ans.equalsIgnoreCase("ampere"))
      {System.out.println(correct);}
      else
      {System.out.println(wrong);}

     break;
    default:
    System.out.println("Stick to the rules! 1-5!");
     }

  }
   else
   {System.out.println("Not liking that attitude, I want to hear a big yes!");}

 }
}

我不确定它是否跳过了 ans 定义或者我是否遗漏了某些内容。另外，如果有其他建议，我将不胜感激:)

Answer 1

尝试替换

ret = sc.nextLine();

与

ret = sc.nextLine();
ret = ret.replace("\n","").replace("\t","").trim();

它会删除任何换行符(或制表符)并删除所有尾随和前导空格(这些东西经常会出现)是什么

编辑:

只需使用 sc.nextLine() 在所有行之后放置这样的行，如果我是对的，它应该解决问题

编辑:那不是问题。当你执行 sc.readByte 时，它​​读取了 2 个字节 - 字符和换行符。当您下次执行 sc.nextLine 时，它​​将获得剩余的换行符。解决办法:

Scanner sc = new Scanner(System.in);
       String ret;
       String qnum;
       String ans;

       String correct = "Awesomely correct!";
       String wrong = "Darn it! Almost got it!";

       System.out.println("Do you think you know your stuff?");
       ret = sc.nextLine();

       if (ret.equals("yes") || ret.equals("Yes"))
       {
        System.out.println("Well, then let's test what you know! Choose a number from 1 to 5!");
        qnum = sc.nextLine();
          switch (qnum)
          {
         case "1":
        System.out.println("In what year did the French Revolution start?");
        ans = sc.nextLine();
          if (ans.equals("1789") || ans.equalsIgnoreCase("seventeen eighty nine"))
          {System.out.println(correct);}
          else
          {System.out.println(wrong);}

         break;

        case "2":
        System.out.println("How many protons does a sodium atom have?");
        ans = sc.nextLine();
        sc.nextLine();
          if (ans.equals("11") || ans.equalsIgnoreCase("eleven"))
          {System.out.println(correct);}
          else
          {System.out.println(wrong);}

         break;

        case "3":
        System.out.println("What is 2^6*0.5-12?");
        ans = sc.nextLine();
        sc.nextLine();
          if (ans.equals("20") || ans.equalsIgnoreCase("twenty"))
          {System.out.println(correct);}
          else
          {System.out.println(wrong);}

         break;

        case "4":
        System.out.println("Which is the lowest numbered element in the periodic table?");
        ans = sc.nextLine();
        sc.nextLine();
          if (ans.equalsIgnoreCase("hydrogen"))
          {System.out.println(correct);}
          else
          {System.out.println(wrong);}

         break;

        case "5":
        System.out.println("Which is the unit that measures Coulombs per second?");
        ans = sc.nextLine();
        sc.nextLine();
          if (ans.equalsIgnoreCase("ampere"))
          {System.out.println(correct);}
          else
          {System.out.println(wrong);}

         break;
        default:
        System.out.println("Stick to the rules! 1-5!");
         }

      }
       else
       {System.out.println("Not liking that attitude, I want to hear a big yes!");}

我在代码中所做的更改是将 qnum 的类型更改为 String，更改了 case 语句以使用字符串，并将 readByte 更改为 readLine。另外，我删除了第二个不需要的新行。