虽然循环和嵌套，如果语句

Question

我想写一个程序，随机生成一个数字，用户试图猜测数字。该程序会记录猜测正确数字的次数。我遇到的问题是越过while循环。当我运行该程序时，它不会超过while循环，直到我点击-1，在这种情况下，它会输出"Your number is too low"。我不确定我错在哪里。

import java.util.Scanner; 
import java.util.Random; 

public class DoGuessingGame 
{ 
public static void main(String[] args) 
{ 

    int number1, userInput; //assign vars 
    int tries = 0; 

    Random rand = new Random();  
    Scanner keyboard = new Scanner(System.in); //define Random and scanner input 


    System.out.println("Welcome to the Guessing Game!"); 
    System.out.println("-----------------------------"); 

    number1 = rand.nextInt(20) + 1; 

    do 
    { 
     System.out.println("\nI'm thinking of a number between 1 and 20. Enter -1 if you would like to quit"); 
     userInput = keyboard.nextInt(); 
     tries++; 
    } 
    while(userInput != -1); 
    { 
     if (userInput > 0 && userInput < 21) 
     { 
      if(userInput == number1) 
      { 
       System.out.println("That is the correct number"); 
       tries++; 
       System.out.println("The Number of tries: " + tries); 
       System.out.println("Game Over."); 

      } 
      else if(userInput > number1) 
      { 
       System.out.println("Your number is too high"); 
       System.out.println("Please try again"); 
       userInput = keyboard.nextInt(); 
       tries++; 
      } 
      else if(userInput < number1); 
      { 
       System.out.println("Your number is too low"); 
       System.out.println("Please try again"); 
       userInput = keyboard.nextInt(); 
       tries++; 
      } 
     } 
     else 
     { 
      System.out.println("Please enter a number between 1 and 20"); 
     } 

    } 
    System.out.println("The number of tries: " + tries); 
} 

}

Answer 1

您的嵌套和放置大括号是令人困惑的。难怪你有问题。

学习更注重风格和可读性。

我没有编译或运行你的代码。我没有深思，看看你是否正确做到了这一点。但我可能会这样做更多：

import java.util.Scanner; 
import java.util.Random; 

public class DoGuessingGame 
{ 
    public static void main(String[] args) { 

    int number1, userInput; //assign vars 
    int tries = 0; 

    Random rand = new Random();  
    Scanner keyboard = new Scanner(System.in); //define Random and scanner input 

    System.out.println("Welcome to the Guessing Game!"); 
    System.out.println("-----------------------------"); 

    number1 = rand.nextInt(20) + 1; 

    do 
    { 
     System.out.println("\nI'm thinking of a number between 1 and 20. Enter -1 if you would like to quit"); 
     userInput = keyboard.nextInt(); 
     tries++; 
     if (userInput > 0 && userInput < 21) { 
      if(userInput == number1) { 
       System.out.println("That is the correct number"); 
       System.out.println("The Number of tries: " + tries); 
       System.out.println("Game Over."); 
       userInput = -1; 
      } else if(userInput > number1) { 
       System.out.println("Your number is too high"); 
       System.out.println("Please try again"); 
      } else if(userInput < number1) { 
       System.out.println("Your number is too low"); 
       System.out.println("Please try again"); 
      } 
     } else { 
      System.out.println("Please enter a number between 1 and 20"); 
     } 
    } while(userInput != -1); 
    System.out.println("The number of tries: " + tries); 
} 

Answer 2

你的do/while循环是没有做什么你认为。您有：

do { 
    System.out.println("\nI'm thinking of a number between 1 and 20. Enter -1 if you would like to quit"); 
    userInput = keyboard.nextInt(); 
    tries++; 
} while(userInput != -1); 

代码下面这一点是do while循环后执行，因此userInput永远是-1，当你来到这里！

Answer 3

我觉得你做.... while循环应该是这样的

do 
    { 
     System.out.println("\nI'm thinking of a number between 1 and 20. Enter -1 if you would like to quit"); 
     userInput = keyboard.nextInt(); 
     tries++; 

if (userInput > 0 && userInput < 21) 
     { 
      if(userInput == number1) 
      { 
       System.out.println("That is the correct number"); 
       tries++; 
       System.out.println("The Number of tries: " + tries); 
       System.out.println("Game Over."); 

      } 
      else if(userInput > number1) 
      { 
       System.out.println("Your number is too high"); 
       System.out.println("Please try again"); 
       userInput = keyboard.nextInt(); 
       tries++; 
      } 
      else if(userInput < number1); 
      { 
       System.out.println("Your number is too low"); 
       System.out.println("Please try again"); 
       userInput = keyboard.nextInt(); 
       tries++; 
      } 
     } 
     else 
     { 
      System.out.println("Please enter a number between 1 and 20"); 
     } 
    } 
    while(userInput != -1); 

Answer 4

你有你的do-while循环后直接一个额外的一对大括号，以及直接分号if语句之后，将改变你的程序的流程。

else if(userInput < number1);