java collections concept
TRANSCRIPT
Need of collection framework?
Due to limitation of arrays Arrays store homogenous data types only and fixed size Collections allowed to store heterogeneous data types with
growable size Collection Framework is set of several classes and interfaces
that helps to achieve this target
9 key interfaces of collection framework
Collection List Set SortedSet NavigableSet Queue Map SortedMap NavigbleMap
1- Collection
Whenever we would like to represent a group of objects as a single entity, we use Collection for the same
It is also known as root interface of collections framework but not completely
There is no concrete class that implements collection interface directly
It defines most common methods which are applicable on any collection object -
2- List
List is child interface of Collection Representing a group of object as a single entity with the
condition that - Duplicates are allowed Insertion order is preserved
Duplicates identified by index Preserving insertion order by index Index has very important role
3- Set
It is child interface of Collection Representing a group of object as a single entity with the
condition that - Duplicates are not allowed Insertion order is not preserved
4- SortedSet
It is child interface of Set Representing a group of object as a single entity with the
condition that - Duplicates are not allowed Insertion order is not preserved Objects should be stored in some sorted order
5- NavigableSet
It is child interface of SoretdSet It defines several methods for navigation purpose TreeSet is the implementation class
6- Queue
It is the child interface of Collection If we want to represent a group of objects prior to processing
then we should go for Queue For e.g. suppose we have to send email to 100 email id’s so we have
to store it somewhere and the emails will be delivered in the same order they were saved
Wait a min before next…
All discussed 6 interfaces Collection, List, Set, SoretdSet, NavigableSet, Queue meant for representing a group of individual object as a single entity
If we want a represent group of objects as key-value pairs then we should go for Map interface
7- Map
Map interface is not the child of Collection interface If we want to represent a group of objects as key-value pairs then
should go for Map Both key and value are objects Duplicate key is not allowed, value can be duplicate
8- SortedMap
It is the child interface of Map If we want to represent a group of key value pairs as per some
sorting order then SortedMap is used
9- NavigableMap
It is the child interface of SoretdMap It defines several utility methods for navigation purpose TrreeMap is the implementation class
References
Durgasoft java tutorial http://durgasoft.com/ Oracle
https://docs.oracle.com/javase/7/docs/api/java/util/Collections.html
Thank you!