Contiguous memory locations are usually used for storing actual values in an array but not in ArrayList. Explain.

 In Java, an array is a fixed-size collection of elements of the same type. When an array is created, the Java runtime system allocates a contiguous block of memory to store the elements of the array. The elements of the array are stored in contiguous memory locations, which means that they are stored one after the other in memory with no gaps between them.

On the other hand, an ArrayList is a resizable collection of elements that is implemented using an array as the underlying data structure. However, an ArrayList is not a fixed-size data structure like an array, and it can grow or shrink dynamically as elements are added or removed.

When an ArrayList is created, it is initially backed by an array with a default size. As elements are added to the ArrayList, the array may need to be resized to accommodate the new elements. If the array needs to be resized, a new array is created with a larger capacity, and the elements of the original array are copied into the new array.

Since an ArrayList can resize dynamically, it is not necessary for the elements to be stored in contiguous memory locations. The elements of an ArrayList are stored in the underlying array, but the array may be resized as needed, which means that the elements may not always be stored in contiguous memory locations.

Overall, the main difference between an array and an ArrayList is that an array is a fixed-size data structure, while an ArrayList is a resizable data structure. This means that the elements of an array are always stored in contiguous memory locations, while the elements of an ArrayList may not be stored in contiguous memory locations.