Thursday, May 19, 2011

List Implementations in java

Being a Collection subtype all methods in the Collection interface are also available in the List interface.

Since List is an interface you need to instantiate a concrete implementation of the interface in order to use it. You can choose between the following List implementations in the Java Collections API:

  • java.util.Vector
    Vectors(Java 1.1) (Click on link to see tutorial on it)

    --uses array to implement list
  • java.util.ArrayList
    ArrayList (Click on link to see tutorial on it)
    --uses array to implement List
    – not thread-safe, otherwise same as Vector
  • java.util.LinkedList
    LinkedList  (Click on link to see tutorial on it)

    --List interface implemented as a doubly-linked list
    – access to elements is not constant time
    – better performance for frequent add/remove operations in middle of List
  • java.util.Stack
There are also List implementations in the java.util.concurrent package, which we will see later.

Here are a few examples of how to create a List instance:

List listA = new ArrayList();
List listB = new LinkedList();
List listC = new Vector();
List listD = new Stack();

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