ArrayList vs LinkedList in Java
An array is a collection of items stored at contiguous memory locations. The idea is to store multiple items of the same type together. However, the limitation of the array is that the size of the array is predefined and fixed. There are multiple ways to solve this problem. In this article, the difference between two classes that are implemented to solve this problem named ArrayList and LinkedList is discussed.
ArrayList is a part of the collection framework. It is present in the java.util package and provides us dynamic arrays in Java. Though, it may be slower than standard arrays but can be helpful in programs where lots of manipulation in the array is needed. We can dynamically add and remove items. It automatically resizes itself. The following is an example to demonstrate the implementation of the ArrayList.
[1, 2, 3, 4, 5] [1, 2, 3, 5]
LinkedList is a linear data structure where the elements are not stored in contiguous locations and every element is a separate object with a data part and address part. The elements are linked using pointers and addresses. Each element is known as a node. Due to the dynamicity and ease of insertions and deletions, they are preferred over the arrays. The following is an example to demonstrate the implementation of the LinkedList.
Note: This class implements the LinkedList Data Structure.
[A, B, C] Linked list after deletion: [C]
Now after having an adequate understanding of both of them let us do discuss the differences between ArrayList and LinkedList in Java
|1.||This class uses a dynamic array to store the elements in it. With the introduction of generics, this class supports the storage of all types of objects.||This class uses a doubly linked list to store the elements in it. Similar to the ArrayList, this class also supports the storage of all types of objects.|
|2.||Manipulating ArrayList takes more time due to the internal implementation. Whenever we remove an element, internally, the array is traversed and the memory bits are shifted.||Manipulating LinkedList takes less time compared to ArrayList because, in a doubly-linked list, there is no concept of shifting the memory bits. The list is traversed and the reference link is changed.|
|3.||Inefficient memory utilization.||Good memory utilization.|
|4.||It can be one, two or multi-dimensional.||It can either be single, double or circular LinkedList.|
|5.||Insertion operation is slow.||Insertion operation is fast.|
|6.||This class implements a List interface. Therefore, this acts as a list.||This class implements both the List interface and the Deque interface. Therefore, it can act as a list and a deque.|
|7.||This class works better when the application demands storing the data and accessing it.||This class works better when the application demands manipulation of the stored data.|
|8.||Data access and storage is very efficient as it stores the elements according to the indexes.||Data access and storage is slow in LinkedList.|
|9.||Deletion operation is not very efficient.||Deletion operation is very efficient.|
|10.||It is used to store only similar types of data.||It is used to store any types of data.|
|11.||Less memory is used.||More memory is used.|
|12.||The memory is allocated at compile-time only.||The memory is allocated at run-time.|
|13.||This is known as static memory allocation.||This is known as dynamic memory allocation.|