Zeek_88 & 89_Collections Framework and Hierarchy (Starting Advanced Java)

                          STARTING ADVANCED JAVA

                                                  

COLLECTIONS FRAMEWORK 

--> The Collection in Java is a framework that provides an architecture to store and manipulate the           group of objects.

 --> Java Collections can achieve all the operations that you perform on a data such as                                        searching, sorting, insertion, manipulation, and deletion.

--> Java Collection means a single unit of objects. 

--> Java Collection framework provides many interfaces (Set, List, Queue, Deque) and                             classes (ArrayList, Vector, LinkedList, PriorityQueue, HashSet, LinkedHashSet, TreeSet).

Why do we need collections ?

We need collections for efficient storage and better manipulation of data in java

For ex: we use arrays to store integers but what if we want to

• Resize this array? 
• Insert an element in between? 
• Delete an elements in Array?
• Apply certain operations to change this array?

Our code becomes time consuming and inefficient if we do not use concept of collections for above 

mentioned situations.

How are collections available?

Collections in java are available as class and interfaces Folling are few commonly used collections in java :

• ArrayList ->  For variables size collections 
• ............................................................................................
• Set ->             For distinct collection
• ...........................................................................................
• Stack->          A LIFO data structure 
• ............................................................................................
• HashMap ->  For strong key - value pairs

Collections class is available in java util package collection class also provides static methods for sorting , searching etc.

Hierarchy of Collection Framework

Let us see the hierarchy of Collection framework. The java.util package contains all the classes and interfaces for the Collection framework

HIERARCHY OF COLLECTION FRAMEWORK