List(Interface) & Child classes of List Interface

List Interface 

• We can preserve Insertion order via Indexed.
• We can differentiate Duplicate order via Indexed.
• Index will play very important role in List.
• List Interface defines the following Specific Methods.

8 Methods are present in List 

• void add(int index, Object o).
• boolean addAll(int index, Collection c).
• object get(int index).
• object remove(int index)
• object set(int index, Object new)[To replace the element present at specified index with provided Object & returns Old objects]
• int indexOf (Object O)[Returns index of first occurrence of 'o']
• int lastIndexOf(Object o)
• ListIterator listIterator()

1. ArrayList

• The underlying data structure is Resizable Array & Growable Array.
• Duplicates are allowed.
• Insertion Order Preserved.
• Heterogeneous Objects are allowed[It means Different type of Objects].
• Null Insertion is Possible.

Constructor

In ArrayList 3 types of Constructor are available

  a).ArrayList l = new ArrayList();

• It means Create empty ArrayList object with default intial Capacity.
• for eg:- The capacity is 10.
• One's ArrayList reaches Max Capacity than a new ArrayList object will be created

   new Capacity = (current Capacity*3/2)+1

      b. ArrayList l = new ArrayList(int intialCapacity);

• Creates an empty ArrayList Objects with Specified Intial Capacity.

  c.ArrayList l = new ArrayList(Collection c);

• Creates an equivalent ArrayList object for the given Collection.

Note:-

• Usually we use Collection to hold underlying objects from One Location to another Location[Container]. To provide Support for this requirement every collection class by default implements Serializable and the Cloneable Interface.
• ArrayList & Vector class implements Random Access Interface so, that any Random element with the access with same speed.
• Random Access Interface present in Java.util Package. Doesn't contain any Methods. It is Marker Interface Required ability will be provided by JVM.

 When ArrayList is Worst Choice?

• If our Frequent Operation is Insertion & Deletion in a middle. 

 When ArrayList is Best Choice and Why?

• If Our Frequent Operation is Retrieval Operation.
• Because ArrayList implements Random Access Interface. 

How to get Synchronized Version of ArrayList Object?

• By default ArrayList is Non-Synchronized but we can get Synchronized version of ArrayList object.
• By using SynchronizedList Method of Collection Class.
• For eg:

     ArrayList l = new ArrayList();

     List l1 = collections.synchronizedList(l);

2.LinkedList

• The Underline data structure(Double/Doubly LinkedList).
• Insertion Order is Preserved.
• Duplicates are allowed.
• Heterogeneous Objects allowed.
• Null Insertion is Possible.
• LinkedList implements Searlizable & Cloneable Interfaces.
• Not Implements Random Access Interface.

Constructor 

     a. LinkedList l = new LinkedList();

• Creates an Empty LinkedList Object.

  b. LinkedList l = new LinkedList(collection c);

• Creates an Equivalent LinkedList object for the given Collection.

LinkedList Specific Methods

• void addFirst(object o);
• void addLast(object o);
• Object getFirst();
• Object getLat();
• Object removeFirst();
• Object removeLast();

Usually We can use LinkedList to implements Stack & Queue.

What is Difference B/w LinkedList & ArrayList?

3.Vector

• The Underlying data Structure is Resizable Array & Growable Array.
• Insertion Order Preserved.
• Duplication are allowed.
• Heterogeneous Objects are allowed.
• Null Insertion is possible.
• It Implements Serializable, cloneable & Random Access Interface.
• Every Method present in the Vector is Synchronized and Vector Object is Thread-Safe.

Constructor

a. Vector v = new Vector();

• Creates an empty vector Object with default initial Capacity 10.
• Once, Vector reaches it's Max Capacity than, New Vector Object will be created with 
•      New capacity=current capacity*2 

b. Vector v = new Vector(int initial capacity);

• Creates an empty Vector Object with Specified initial Capacity.

c.  Vector v = new Vector(int initialcapacity , int                 incrementalcapacity).

• for eg: Vector v = new v (1000, 5);

d. Vector v =new Vector(collection c);

•   Creates an equivalent vector object for the given collection these constructor meant for interconversion B/w Collection Objects. 

  

What is Difference B/w ArrayList & Vector?

Methods

• int Size();
• int Capacity();
• Enumeration element();
• addElement(Object o);
• removeElement(object o);
• object get(int index); 

Stack

• It is Child Class of Vector.
• It is Specially Designed Class Last In First Out.(LIFO).

Constructor

Stack s = new Stack();

Methods

• Object push(object o);

     To Insert an Object into Stack.

• Object pop();

     To Remove & Return Top of the Stack.

• Object peek();

     To return Top of the Stack without Removal.

• Boolean empty();

     Returns true If the Stack is Empty.

• int Search(object o);

     Return Offset if the element is available otherwise return -1.