java - 捕捉到IllegalArgumentException？

我在这里有点问题。我试图弄清楚如何捕获IllegalArgumentException。对于我的程序，如果用户输入一个负整数，则程序应捕获IllegalArgumentException并询问用户是否要重试。但是，当引发异常时，它不会提供该选项。它只是终止。我尝试使用try and catch方法，但对我不起作用。如何捕获此特殊异常以继续运行而不是终止？

public static void main(String[] args) throws IllegalArgumentException
{
    String keepGoing = "y";
    Scanner scan = new Scanner(System.in);
    while(keepGoing.equals("y") || keepGoing.equals("Y"))
    {
        System.out.println("Enter an integer: ");
        int val = scan.nextInt();
        if (val < 0)
        {
            throw new IllegalArgumentException
            ("value must be non-negative");
        }
        System.out.println("Factorial (" + val + ") = "+ MathUtils.factorial(val));
        System.out.println("Another factorial? (y/n)");
        keepGoing = scan.next();
    }
}

}

和

public class MathUtils
{
    public static int factorial(int n)
    {
        int fac = 1;
        for(int i = n; i > 0; i--)
        {
            fac *= i;
        }
        return fac;
    }
}

最佳答案

您需要在循环内添加try catch块以继续循环工作。一旦遇到非法参数异常，将其捕获在catch块中，并询问用户是否要继续

import java.util.Scanner;

public class Test {
public static void main(String[] args)
{
String keepGoing = "y";
populate(keepGoing);

}

static void populate( String keepGoing){
  Scanner scan = new Scanner(System.in);
 while(keepGoing.equalsIgnoreCase("y")){
     try{
        System.out.println("Enter an integer: ");
        int val = scan.nextInt();
        if (val < 0)
        {
            throw new IllegalArgumentException
            ("value must be non-negative");
        }
        System.out.println("Factorial (" + val + ") = "+ MathUtils.factorial(val));
        System.out.println("Another factorial? (y/n)");
        keepGoing = scan.next();
    }
    catch(IllegalArgumentException i){
        System.out.println("Negative encouneterd. Want to Continue");
        keepGoing = scan.next();
        if(keepGoing.equalsIgnoreCase("Y")){
        populate(keepGoing);
        }
    }
    }
}
}

希望这可以帮助。
快乐学习：）

关于java - 捕捉到IllegalArgumentException？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/26960941/