Question

我正在构建一个带有数组数组的类，并且有方法输出它们的最小值，最大值和平均值作为数字的字符串表示形式。这是我班级的构造函数：

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，我正在获取数组超出范围的异常消息，并且此构造函数是导致它的那个。我无法理解我如何超越数组的大小。请帮忙！感谢。

编辑 - 所以只是为了澄清任何混淆我在下面发布整个课程以供参考：

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

您的方法传递的是数组的大小，但代码中不存在数组定义。

如果需要在RandomArray方法中创建数组，请执行以下操作：

public int[] RandomArray(int sizeOfArray)/*Constructor: gets array size, create and populates  array with   random numbers*/ 
   {
       int[] randomArray = new int[sizeOfArray];
       for (int i = 0;i < randomArray.length();i++)
       {
           numbers[i] = generator.nextInt(size + 1);
       }
       return randomArray;
   }

Answer 2

在初始化size变量之前，您正在初始化数组。 size变量具有默认值，该值传递给数组构造函数并将数组设置为该大小。修复问题只需在设置size变量后将数组的初始化移动到构造函数中。

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);
   }
}

此外，我还注意到了字符串输出方法的错误。每次迭代都会覆盖该数组。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;
}

Answer 3

由于您没有提供整个班级代码，因此很难看到最新情况。但是我认为你没有正确初始化数组。如果你有一个数组的私有变量，你仍然应该为它“腾出空间”，如下所示。

private int[] myIntArray; // As class member


myIntArray = new int[3]; // To allocate memory for the array

有关阵列的更多信息，请参阅以下链接。

https://docs.oracle.com/javase/tutorial/java/nutsandbolts/arrays.html

java数组索引超出范围

3 个答案: