java数组索引越界

Question

我正在构建一个类，它接受数字数组，并具有将其最小值、最大值和平均值输出为数字的字符串表示形式的方法。这是我的类的构造函数:

public RandomArray(int sizeOfArray)/*Constructor: gets array size and populates array with
   random numbers*/ 
   {
       Random generator = new Random();

       size = sizeOfArray;

       for (int i = 0;i < size;i++)
       {
           numbers[i] = generator.nextInt(size + 1);
       }
   }

当我使用驱动程序测试此类时，我收到数组越界异常消息，并且此构造函数是导致该消息的原因。我无法理解我如何超出这里的数组大小。请帮忙!谢谢。

编辑 - 为了消除任何困惑，我将整个类(class)发布在下面以供引用:

public class RandomArray
{
/*A class that contains an array of random numbers and methods that output
   the numbers' minimum, maximum and average values. Also includes a method
   that outputs a string representation of the numbers.*/
   int size, min, max;
   String array;
   int[] numbers = new int[size];

   public RandomArray(int sizeOfArray)/*Constructor: gets array size and populates array with
   random numbers*/ 
   {
       Random generator = new Random();

       size = sizeOfArray;

       for (int i = 0;i < size;i++)
       {
           numbers[i] = generator.nextInt(size + 1);
       }
   }

   public int min_value()
   {
       for (int i = 0;i < size - 1;i++)
       {
           min = numbers[i];
           for (int k = 1;k < size; k++)
           {
               if (numbers[k] < min)
               {
                   min = numbers[k];
               }
               else
               {
                   min = numbers[i];
               }
           }
       }

       return min;
   }

   public int max_value()
   {
       for (int i = 0;i < size - 1;i++)
       {
           max = numbers[i];
           for (int k = 1;k < size; k++)
           {
               if (numbers[k] > max)
               {
                   max = numbers[k];
               }
               else
               {
                   max = numbers[i];
               }
           }
       }

       return max;
   }

   public double average()
   {
       double avg;
       int sum = 0;

       for (int i = 0;i < size;i++)
       {
           sum = sum + numbers[i];
       }

       avg = sum/size;

       return avg;
   }

   public String toStringArray()//Outputs a string representation of all the numbers in the array
   {
       for (int i = 0; i < size;i++)
       {
           array = Integer.toString(numbers[i]) + " ";
       }

       return array;
   }

}

Answer 1

您将在初始化大小变量之前初始化数组。 size 变量有一个默认值，该值被传递到数组构造函数中并将数组设置为该大小。要解决此问题，只需在设置大小变量后将数组的初始化移至构造函数中即可。

public class RandomArray
{
    /*A class that contains an array of random numbers and methods that output
   the numbers' minimum, maximum and average values. Also includes a method
   that outputs a string representation of the numbers.*/
   int size, min, max;
   String array;
   int[] numbers;

   public RandomArray(int sizeOfArray) {
   Random generator = new Random();

   size = sizeOfArray;

   numbers = new int[size];

   for (int i = 0;i < size;i++)
   {
       numbers[i] = generator.nextInt(size + 1);
   }
}

我还注意到字符串输出方法的一个错误。该数组将在每次迭代时被覆盖。要解决此问题，您必须将数组添加到自身。

public String toStringArray()//Outputs a string representation of all the numbers in the array
{
   for (int i = 0; i < size;i++)
   {
       array = array + Integer.toString(numbers[i]) + " ";
   }

   return array;
}