哪里可以抛出异常的Java猜测游戏

Question

嗨我目前无法在我的猜测游戏代码上抛出异常。我想为字符串输入（而不是int）输入一个异常，并且输入超出限制（50）的数字也是一个例外。谢谢。

public static void main (String[] args) 

{ 
    Random ran = new Random(); 
    int numberToGuess = ran.nextInt(50)+1; 
    int numberOfTries = 0; 
    Scanner input = new Scanner (System.in); 
    int guess; 
    boolean win = false; 

    while (win == false) 
    { 
     System.out.println("Guess a number from 1 to 50!"); 
     guess = input.nextInt(); 
     numberOfTries++; 

     if (guess == numberToGuess) 
     { 
      win = true; 
     } 
     else if (guess < numberToGuess) 
     { 
      System.out.println("Too low. Try again."); 
     } 
     else if (guess > numberToGuess) 
     { 
      System.out.println("Too high. Try again."); 
     } 
    } 

    System.out.println("You got it in " + numberOfTries + " attempt(s)!"); 

} 

Answer 1

我真的不认为你需要抛出异常。您可以使用 Scanner#hasNextInt()验证输入是整数。然后将其分配给猜测变量，并检查它是否大于50。

如果您真的要抛出异常。使用 throw new RuntimeException(message)如果输入不是整数，或者大于50

编辑： 我不会用它这样的，但我相信你只是想了解的例外。

System.out.println("Guess a number from 1 to 50!"); 
numberOfTries++; 
if (!input.hasNextInt()) 
    throw new IllegalArgumentException("Input must be a number"); 

guess = input.nextInt(); 
if (guess < 1 || guess > 50) 
    throw new IllegalArgumentException("Input must be a number from 1 to 50"); 

Answer 2

这是一个潜在的解决方案：

import org.apache.commons.lang3.StringUtils; 

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

public class StackOverflow45419907 { 
    private final Scanner input; 
    final int numberToGuess; 

    public StackOverflow45419907() { 
    this.input = new Scanner(System.in); 
    numberToGuess = new Random().nextInt(50) + 1; 
    } 

    public static void main(String[] args) { 
    new StackOverflow45419907().playGame(); 
    } 

    private void playGame() { 
    int numberOfTries = 0; 
    int guess = -1; 

    while (guess != numberToGuess) { 
     guess = collectGuess(); 
     numberOfTries++; 

     printClue(guess); 
    } 
    System.out.println("You got it in " + numberOfTries + " attempt(s)!"); 
    } 

    private void printClue(int guess) { 
    if (guess < numberToGuess) { 
     System.out.println("Too low. Try again."); 
    } else if (guess > numberToGuess) { 
     System.out.println("Too high. Try again."); 
    } 
    } 

    private int collectGuess() { 
    System.out.println("Guess a number from 1 to 50!"); 
    final String potentialGuess = input.nextLine(); 
    return validateAndParse(potentialGuess); 
    } 

    private int validateAndParse(String potentialGuess) { 
    if (!StringUtils.isNumeric(potentialGuess)) { 
     throw new IllegalArgumentException("not numeric: " + potentialGuess); 
    } 
    final int asInt = Integer.parseInt(potentialGuess); 
    if (asInt > 50 || asInt < 1) { 
     throw new IllegalArgumentException("value out of valid range: " + asInt); 
    } 
    return asInt; 
    } 
}