java - 为什么我的程序没有显示正确的输出？

Question

这个问题已经有答案了:

How do I compare strings in Java? (23 个回答)

已关闭 9 年前。

首先，我对编程还是个新手。我的任务是制作一个没有数组的石头剪刀布程序。根据我们之前的选择，程序会选择相应的武器。在程序结束时，如果用户不想继续，我们会显示他们的总体分数。所有这些都应该在我们在 main 内部调用的另一个方法中。

正如我之前所说，我对编程非常陌生，因此除了数组之外，if else 语句是我知道如何执行此操作的唯一方法(还有很多方法)。

import java.util.Scanner;

public class ASSIGNMENT
{
  public static void main (String [] args)
  { 
     game();

  }//end main

  public static void game ()
  {
     Scanner kb = new Scanner(System.in);

     //assigning variables
     int rock = 1; 
     int scissors = 2; 
     int paper = 3; 
     int weaponAI = 0;
     int weaponP = 0;
     int wins = 0;
     int losses = 0;
     int ties = 0;
     int rockNum = 0;
     int scissorsNum = 0;
     int paperNum = 0;
     String yorn;

     do
     {
        //generate random numbe to decide weapon
        double weaponNum = (Math.random() * 3)+ 1;
        System.out.println(weaponNum);
        if (weaponNum >= 1 && weaponNum < 2)
        {  
           if (rockNum > scissorsNum && rockNum > paperNum)
              weaponAI = paper;
           else if (paperNum > scissorsNum && paperNum > rockNum)
              weaponAI = scissors;
           else
              weaponAI = rock;
        }
        else if (weaponNum >= 2 && weaponNum < 3)
        {
           if (scissorsNum > rockNum && scissorsNum > paperNum)
              weaponAI = rock;
           else if (paperNum > scissorsNum && paperNum > rockNum)
              weaponAI = scissors;
           else
              weaponAI = paper;
        }
        else if (weaponNum >= 3)
        {
           if (scissorsNum > rockNum && scissorsNum > paperNum)
              weaponAI = rock;
           else if (rockNum > scissorsNum && rockNum > paperNum)
              weaponAI = paper;
           else
              weaponAI = scissors;
        }
        //prompting for guess and assigning
        System.out.println("BATTLE START!");
        System.out.println("Choose your weapon: ");
        String weaponStr = kb.nextLine();
        if (weaponStr == "Rock" || weaponStr == "rock")
        {
           weaponP = rock;
           ++rockNum;
        }
        else if (weaponStr == "Scissors" || weaponStr == "scissors")
        {
           weaponP = scissors;
           ++scissorsNum;
        }
        else if (weaponStr == "Paper" || weaponStr == "paper")   
        {
           weaponP = paper;
           ++paperNum;
        }
        else if (weaponStr =="quit" || weaponStr == "Quit")
           System.exit(-1);

        //comparing AI and Players weapon
        //tied
        if (weaponAI == rock && weaponP == rock)
        {
           System.out.println("You both chose rock");
           ++ties;
        }
        else if (weaponAI == paper && weaponP == paper)
        {
           System.out.println("You both chose paper");
           ++ties;
        }   
        else if (weaponAI == scissors && weaponP == scissors)
        {
           ++ties;
           System.out.println("You both chose scissors");
        }
        //AI wins
        else if (weaponAI == rock && weaponP == scissors)
        {
           ++losses;
           System.out.println("AI wins");
        }
        else if (weaponAI == paper && weaponP == rock)
        {
           ++losses;
           System.out.println("AI wins");
        }
        else if (weaponAI == scissors && weaponP == paper)
        {
           ++losses;
           System.out.println("AI wins");
        }
        //Player wins
        else if (weaponAI == scissors && weaponP == rock)
        {
           ++wins;
           System.out.println("You win!");
        }
        else if (weaponAI == rock && weaponP == paper)
        {
           ++wins;
           System.out.println("You win!");
        }
        else if (weaponAI == paper && weaponP == scissors)
        {
           ++wins;
           System.out.println("You win!");
        }
        //prompting user to play again
        System.out.println("Would you like to play again? Y or N?");
        yorn = kb.nextLine();

     }//end do
     while (yorn == "y" || yorn == "Y" || yorn == "Yes" || yorn == "yes");

     //Displaying scores
     System.out.println("Game over.");
     System.out.println("You had " + wins + " wins.");
     System.out.println("You had " + losses + " losses.");
     System.out.println("You had " + ties + " ties.");
     System.out.println("You chose rock " + rockNum + " times.");
     System.out.println("You chose paper " + paperNum + " times.");
     System.out.println("You chose scissors " + scissorsNum + " times.");

  }//end game
}//end class

我不确定为什么当我输入“rock”和“y”时我的输出如下

1.5102368482522261

BATTLE START!

Choose your weapon:

rock

Would you like to play again? Y or N?

y

Game over.

You had 0 wins.

You had 0 losses.

You had 0 ties.

You chose rock 0 times.

You chose paper 0 times.

You chose scissors 0 times.

这几乎就像程序忽略了我所有的 if else 语句。我确信这是一些我不明白的简单事情......

Answer 1

为了比较 String 内容，您必须将 == 替换为 equalsIgnoreCase()。

您不能使用 == 运算符比较两个字符串内容。 java中的==运算符比较字符串引用(如果一个对象与另一个对象相同)

为了让你的代码正常工作，你需要这样的东西:

if (weaponStr.equalsIgnoreCase("Rock")){
  ...
}

要了解 Java 中如何进行字符串比较，您还可以查看:

• How do I compare strings in Java?
• Java String.equals versus ==