The Difference between ArrayList and LinkedList in Java
Java is an important programming language utilized by software developers to build web, desktop, and mobile applications. Among the various advanced data structures that Java offers, ArrayList and LinkedList are two of the most commonly used ones. While both data structures are used to store a collection of objects, they differ from each other in their implementation, performance, and usage.
ArrayList
ArrayList is a dynamically resizable array data structure in Java, which means it can grow and shrink as necessary according to the requirements of the programmer. It stores elements in a contiguous block of memory and uses an index-based system to access and modify the elements in the list. The elements can be inserted or removed from the middle of the list, but it can be a slow operation because it requires shifting all the elements on the right side of the insertion or removal point.
ArrayList is especially useful when you need to perform a large number of random access or retrieval operations, such as searching for an element in the list by its index. However, it is less efficient when it comes to adding or removing elements from the list.
LinkedList
LinkedList is another frequently used data structure in Java, but it differs from ArrayList in its implementation. Rather than storing the elements in a contiguous block of memory, LinkedList stores the elements in a series of nodes, where each node contains a reference to its preceding and succeeding nodes. This allows for efficient and fast insertion and removal of elements from the list, especially when they are added or removed from the beginning or end of the list.
LinkedList is ideal for scenarios where the number of elements in the list frequently changes, and operations such as adding, deleting, or re-ordering elements are important. It is also useful when the elements in the list need to be accessed sequentially, such as traversing the list from the beginning to end.
Conclusion
The choice between using an ArrayList or a LinkedList in Java depends on the requirements of your program. If you need to perform a large number of random access or retrieval operations, choose ArrayList. However, if your program frequently adds or removes elements from the list and the order of the elements is not that important, use LinkedList. In short, ArrayList provides better performance for access operations (get and set) while LinkedList is more efficient for add and remove operations.
Table difference between arraylist and linked list
| ArrayList | LinkedList |
|---|---|
| Implements List interface and extends AbstractList class. | Implements List and Deque interfaces and extends AbstractSequentialList class. |
| Stores elements sequentially in the memory. | Stores elements in nodes and each node has a reference to the next node. |
| Accessing elements by index is faster as it directly retrieves the element from memory. | Accessing elements by index is slower as it has to traverse from the beginning of the list to the required index. |
| Addition and removal of elements at the end of the list is faster. | Addition and removal of elements at any position in the list is faster. |
| It is not suitable for frequent additions and removals at random positions in the list. | It is suitable for frequent additions and removals at random positions in the list. |
| It uses less memory as it does not require pointers to the next node. | It uses more memory as each node requires a pointer to the next node. |