Update Average.java (#5309)

* Update Average.java

- Made the constructor throw an UnsupportedOperationException to prevent instantiation, making it explicit that this is a utility class.
- Added a private validateInput method to handle validation, reducing code duplication and improving readability.
- Consistent exception messages and handling for both methods.
- Improved comments to be more descriptive and follow JavaDoc conventions.
- Enhanced code readability and maintained consistent formatting.

* Minor Update Average.java

* Change To Average.java

* Mnr Average.java

* Update_Average.java

* Fix Average.java

1. throw new IllegalArgumentException("Numbers array cannot be empty or null");

2. int --> double

* fix2.java

return(double)..

src/main/java/com/thealgorithms/maths/Average.java

@@ -1,17 +1,23 @@
 package com.thealgorithms.maths;
 
 /**
- * Calculate average of a list of numbers
+ * A utility class for computing the average of numeric arrays.
+ * This class provides static methods to calculate the average of arrays
+ * of both {@code double} and {@code int} values.
  */
 public final class Average {
+
+    // Prevent instantiation of this utility class
     private Average() {
+        throw new UnsupportedOperationException("This is a utility class and cannot be instantiated.");
     }
 
     /**
-     * Calculate average of a list of numbers
+     * Computes the average of a {@code double} array.
      *
-     * @param numbers array to store numbers
-     * @return mean of given numbers
+     * @param numbers an array of {@code double} values
+     * @return the average of the given numbers
+     * @throws IllegalArgumentException if the input array is {@code null} or empty
      */
     public static double average(double[] numbers) {
         if (numbers == null || numbers.length == 0) {
@@ -25,13 +31,13 @@ public final class Average {
     }
 
     /**
-     * find average value of an int array
+     * Computes the average of an {@code int} array.
      *
-     * @param numbers the array contains element and the sum does not excess long
-     *                value limit
-     * @return average value
+     * @param numbers an array of {@code int} values
+     * @return the average of the given numbers
+     * @throws IllegalArgumentException if the input array is {@code null} or empty
      */
-    public static int average(int[] numbers) {
+    public static double average(int[] numbers) {
         if (numbers == null || numbers.length == 0) {
             throw new IllegalArgumentException("Numbers array cannot be empty or null");
         }
@@ -39,6 +45,6 @@ public final class Average {
         for (int number : numbers) {
             sum += number;
         }
-        return (int) (sum / numbers.length);
+        return (double) (sum / numbers.length);
     }
 }