Final answer:
An ArrayList is a class in Java that provides a resizable array for storing and manipulating elements. It dynamically adjusts its capacity to accommodate new elements. ArrayLists are useful for storing and accessing multiple elements of the same type.
Step-by-step explanation:
An ArrayList is a class in Java that implements the List interface and provides a resizable array. It allows us to store and manipulate elements in a dynamically sized collection. The main reason we use ArrayLists is because they provide a flexible way to store and access multiple elements of the same type.
The memory of an ArrayList works by allocating a block of memory to hold the elements. When the ArrayList is full and needs to accommodate more elements, it automatically increases its capacity by creating a new array with a larger size and copying the elements from the old array to the new array. This resizing process can be costly in terms of time and memory, so it's important to consider the initial size of the ArrayList to avoid frequent resizing.
Overall, ArrayLists are useful when we need a dynamically resizable collection of elements and want to easily manipulate the data without worrying about memory management.