fix(searches): handle null array safely and eliminate raw type warnings in FibonacciSearch

src/main/java/com/thealgorithms/searches/FibonacciSearch.java

@@ -15,20 +15,22 @@
  * Note: This algorithm requires that the input array be sorted.
  * </p>
  */
-@SuppressWarnings({"rawtypes", "unchecked"})
-public class FibonacciSearch implements SearchAlgorithm {
+public final class FibonacciSearch implements SearchAlgorithm {
 
     /**
      * Finds the index of the specified key in a sorted array using Fibonacci search.
      *
      * @param array The sorted array to search.
      * @param key The element to search for.
      * @param <T> The type of the elements in the array, which must be comparable.
-     * @throws IllegalArgumentException if the input array is not sorted or empty, or if the key is null.
+     * @throws IllegalArgumentException if the input array is null, not sorted or empty, or if the key is null.
      * @return The index of the key if found, otherwise -1.
      */
     @Override
     public <T extends Comparable<T>> int find(T[] array, T key) {
+        if (array == null) {
+            throw new IllegalArgumentException("Input array must not be null.");
+        }
         if (array.length == 0) {
             throw new IllegalArgumentException("Input array must not be empty.");
         }
@@ -76,7 +78,7 @@ public <T extends Comparable<T>> int find(T[] array, T key) {
         return -1;
     }
 
-    private boolean isSorted(Comparable[] array) {
+    private <T extends Comparable<T>> boolean isSorted(T[] array) {
         for (int i = 1; i < array.length; i++) {
             if (array[i - 1].compareTo(array[i]) > 0) {
                 return false;

src/test/java/com/thealgorithms/searches/FibonacciSearchTest.java

@@ -94,6 +94,15 @@ void testFibonacciSearchEmptyArray() {
         assertThrows(IllegalArgumentException.class, () -> fibonacciSearch.find(array, key), "An empty array should throw an IllegalArgumentException.");
     }
 
+    /**
+     * Test for Fibonacci search with a null array.
+     */
+    @Test
+    void testFibonacciSearchNullArray() {
+        FibonacciSearch fibonacciSearch = new FibonacciSearch();
+        assertThrows(IllegalArgumentException.class, () -> fibonacciSearch.find(null, 5), "A null array should throw an IllegalArgumentException.");
+    }
+
     @Test
     void testFibonacciSearchUnsortedArray() {
         FibonacciSearch fibonacciSearch = new FibonacciSearch();