Programming

Interview Question: Difference between LinkedList vs ArrayList in Java?

Introduction:

LinkedList and ArrayList both implement List Interface but how they work internally is where the differences lies. Main difference between ArrayList and LinkedList is that ArrayList is implemented using re-sizable array while LinkedList is implemented using doubly LinkedList. ArrayList is more popular among Java programmer than LinkedList as there are few scenarios on which LinkedList is a suitable collection than ArrayList. In this article we will see some differences between LinkedList and ArrayList and try to find out when and where to use LinkedList over ArrayList.

difference between arraylist and linkedlist - WingedPostThe Differences:

  1. Since Array is an index based data-structure searching or getting element from Array with index is pretty fast. Array provides O(1) performance for get(index) method but remove is costly in ArrayList as you need to rearrange all elements. On the Other hand LinkedList doesn’t provide Random or index based access and you need to iterate over linked list to retrieve any element which is of order O(n).
  2. Insertions  are easy and fast in LinkedList as compared to ArrayList because there is no risk of resizing array and copying content to new array if array gets full which makes adding into ArrayList of O(n) in worst case, while adding is O(1) operation in LinkedList in Java. ArrayList also needs to update its index if you insert something anywhere except at the end of array.
  3. Removal is like insertions better in LinkedList than ArrayList.
  4. LinkedList has more memory overhead than ArrayList because in ArrayList each index only holds actual object (data) but in case of LinkedList each node holds both data and address of next  and previous node.

 

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