collections framework in java

the java collection framework is a set of interface and classes. that provides ready-made architecture used to store and manage multiple objects dynamically.

why use collections
array have some limitations:

• fixed size
• difficult insertion and deletion
• Limited built-in operations

collections solve those problems by providing dynamic data structure and useful methods.

main interfaces in collections framework

1. Collection interface
Collection interface is super(parent) interface.

List

list is a sub interface(child) of collection interface.
list extends collection.

List interface supports

1. maintain insertion order
2. Allow duplicate elements
3. Supports index-based access

Example

• ArrayList
• LinkedList

Set

set also sub interface(child) of a collection interface.
set extends collection

Set interface supports

• set dose not allow duplicate
• no index based-access

Example

• HashSet
• LinkedHashSet
• TreeSet

Map

map is a interface, That stores data in key value pairs.

map implemented classes

• HashMap
• LinkedHashMap
• TreeMap
• Hashtable

*Advantage of Collections *

• Dynamic size
• Easy insertion and deletion
• built-in sorting and searching
• better code reusability