feat: Code refactor for AbsoluteValue improvements

I'm refactoring some classes from the `maths` package to have a cleaner,
more concise, easier to maintain and better documented code.

I've also updated the code to use features from newer versions of Java
and I've created some unit tests because it was missing unit tests for
AbsoluteValue (I'm using now unit tests instead of main method to test the
feature).

Resolves: #3017

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

@@ -1,26 +1,14 @@
 package com.thealgorithms.maths;
 
-import java.util.Random;
-
 public class AbsoluteValue {
 
-    public static void main(String[] args) {
-        Random random = new Random();
-
-        /* test 1000 random numbers */
-        for (int i = 1; i <= 1000; ++i) {
-            int randomNumber = random.nextInt();
-            assert absVal(randomNumber) == Math.abs(randomNumber);
-        }
-    }
-
     /**
-     * If value is less than zero, make value positive.
+     * Returns the absolute value of a number.
      *
-     * @param value a number
-     * @return the absolute value of a number
+     * @param number The number to be transformed
+     * @return The absolute value of the {@code number}
      */
-    public static int absVal(int value) {
-        return value < 0 ? -value : value;
+    public static int getAbsValue(int number) {
+        return number < 0 ? -number : number;
     }
 }

src/test/java/com/thealgorithms/maths/AbsoluteValueTest.java

@@ -0,0 +1,18 @@
+package com.thealgorithms.maths;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class AbsoluteValueTest {
+
+    @Test
+    void testGetAbsValue() {
+        Stream.generate(() -> ThreadLocalRandom.current().nextInt())
+                .limit(1000)
+                .forEach(number -> assertEquals(Math.abs(number), AbsoluteValue.getAbsValue(number)));
+    }
+}