Question

我一直坚持用Java来解决餐饮哲学家的问题。

我得到的错误是

＆＃34;线程中的异常＆＃34; main＆＃34; java.lang.ArrayIndexOutOfBoundsException：2       在Main.main（Main.java:43）＆＃34;

第43行是：

rFork = forks[forI + 1];

并且位于
下面的for循环中

for (int i = 0; i < phiNum; i++)
        {
            list[i] = new Philosopher(forks[i], forks[(i + 1) % phiNum], 
                    i, in.nextFloat());
            for (int forI = 0; forI < (phiNum); forI++)
            {
                lFork = forks[forI];
                rFork = forks[forI + 1];
            }
        }

以下是Main.java类的其余代码：

import java.util.*;
public class Main
{
   static Scanner in = new Scanner(System.in);
   public static void main(String[] args)
   {
      int phiNum = 0, maxForks = 2;
      float time = 0;

      System.out.print("Enter the number of Philosophers: ");
      phiNum = in.nextInt();

      //float timeSpentThinking = in.nextFloat();
      Philosopher[] list = new Philosopher[phiNum];
      Fork[] forks = new Fork [phiNum];
      Fork lFork = new Fork();
      Fork rFork = new Fork();

      if (phiNum == 0)
         System.out.println("There are no philosophers eating or 
            thinking.");
      else if (phiNum == 1)
         System.out.println("There are not enough forks for the 
            philosopher" + " to eat.");
      else
      {
         for (int index = 0; index < (phiNum); index++)
            forks[index] = new Fork();
         for (int i = 0; i < phiNum; i++)
         {
            list[i] = new Philosopher(forks[i], forks[(i + 1) % phiNum], 
                    i, in.nextFloat());
            for (int forI = 0; forI < (phiNum); forI++)
            {
               lFork = forks[forI];
               rFork = forks[forI + 1];
            }
         }
      }
      for (int i = 1; i < list.length; i++)
         list[i].run();
   }
}

Answer 1

您声明此变量：

forNum = 0;

并使用它来声明数组：

Fork[] forks = new Fork [forNum];

所以数组是空的，所以试图访问它会给你带来错误。您必须为变量forNum提供非零值，或者要求用户输入分叉数：

System.out.print("Enter the number of forks: ");
forNum = in.nextInt();

学习使用调试器可以帮助您看到数组的大小为零。

需要用餐哲学家的解决方案

1 个答案: