Difference between linked list and array data structure in Java Programming

Array and linked list are two fundamental data structure in programming
world. Almost all programs use Array in some form or other, which makes it
increasingly important to learn array and linked list. Difference between
linked list and array data structure is also a popular data structure question,
frequently asked in various programming job interview. This makes it even more
important to learn and understand difference between an array and a linked list.
Well there are lot of difference between these two starting from how they store
data, to how you retrieve data from them. Main difference comes from the fact
that array elements are stored in contiguous memory location, which makes it
easy to retrieve them in quick time, while linked list elements are scattered
through out memory, where one element knows address of other, it makes it hard
to retrieve element from linked list in quick time. Some of the differences
which we saw in ArrayList vs LinkedList also
applicable at data structure level, because ArrayList is backed
by array and LinkedList is internally backed by double
linked list in Java. In this tutorial, we will learn differences between these
two fundamental data structure in more details. Once you know the difference,
you can make a concise choice of which data structure suits your need better.
Since both of them offers distinctive advantage over others, in terms of speed
and flexibility, You can make an informed choice based upon your need.

Array vs linked list in Java

Here is my list of differences between array and linked list. Though data
structure concept are independent of any programming language and more or less
applicable in all programming language including C and C++, I have explained
differences in Java's context.

1. First and major difference between linked list and array data structure
is that former doesn't support random access, while later support random
access. linked list is sequential, in order to retrieve an element, you need to
traverse till that, while if you know index, you can retrieve an element from
array very quickly, because it doesn't involved traversal.

2. Second major difference between array and linked-list data structure
is that, array needs contiguous memory allocation, which may result in java.lang.OutOfMemoryError: Java Heap
Space if there is not enough contiguous ( a big chunk) of memory in
Java Heap. On the other hand, linked list is distributed data structure, it's
element are scattered over heap and doesn't need a contiguous memory
allocation. This makes linked list ideal, if you have scattered memory.

3. Third major difference is fixed length, array is a fixed length data
structure, you provide length or size of array at the time of creation, later you
can not modify that size. On the other hand, linked list is dynamic data
structure, it can grow and doesn't required size to be specified at the time of
creation, because each node keep tracks of other.

4. It's easy to insert and delete elements from linked list than array,
especially inserting element at beginning of linked list, and deleting element
from end of linked list is O(1) operation. On the other hand array is fixed
length data structure, so memory is allocated during initialization, and doesn't
really change due to addition and removal of elements.  Though you can set a particular index null,
to cut the reference count of that object.

5. Array is ideal for implementing fast caches e.g. HashMap or Hashtable, which
requires constant time retrieval e.g. Map data structure provides O(1)
performance for get(Key key) operation, while linked list
based structure provides liner performance i.e. O(n) for retrieval operation,
where n is the number of elements in linked list.

6. Array can be one or multi-dimensional, while linked list can be
singly, doubly or circular linked list. Two dimensional array are most common
in multi-dimensional and used to represent matrix in Java. You can use two
dimensional array to represent a plain of x,y coordinates, frequently used in
Game programming. Java programming language provides support for creating array
at syntax level, it supports both single and multidimensional array. Java API
also provides a class called java.util.LinkedList, which is
an implementation of doubly linked list data structure.

That's all on my list of differences
between array and linked list data structure. I strongly suggest to get a
good hold of these data structure, especially linked list, which is very
popular among data structure interview questions. Questions like appending
elements into linked list, deleting elements, reversing linked list are quite
common in various programming jobs. At very least, knowledge of fundamental
data structure is essential to do well in programming jobs.

Couple of books in data structure which is worth
reading

1. Data Structure and Algorithm Analysis in Java

2. Data Structures: Abstraction and Design Using Java By Elliot B. Koffman, Paul A.
T. Wolfgang

Source:http://javarevisited.blogspot.com/2013/07/difference-between-array-and-linked-list-java.html