Java Collections Framework:
- Definition: The Java Collections Framework is a set of interfaces, classes, and algorithms provided by Java to handle and manipulate groups of objects, known as collections. It provides a unified architecture for storing, retrieving, and manipulating data in various data structures.
Purpose: The purpose of the Java Collections Framework is to provide a standardized way of working with collections of objects, making it easier to manage data and perform common operations efficiently. It promotes code reuse, modularity, and simplifies the development process by providing ready-to-use collection classes and algorithms.
a. Interfaces: The framework includes several core interfaces such as List, Set, Map, Queue, etc., which define common behaviors and operations for different types of collections.
b. Implementations: The framework offers various concrete classes that implement the interfaces, providing different data structures and algorithms optimized for different scenarios.
c. Algorithms and Utilities: The framework provides algorithms and utility methods for performing common operations on collections, such as sorting, searching, filtering, and more.
d. Iterators: Iterators are used to traverse the elements of a collection in a consistent and efficient manner. e. Generics: The framework extensively uses generics to ensure type safety and enable type-specific collections.
Collection Types:
List: A list is an ordered collection that allows duplicate elements. Elements in a list can be accessed by their index.
- Set: A set is a collection that does not allow duplicate elements. It ensures the uniqueness of elements based on their equality.
Map: A map is a collection that stores key-value pairs. Each key in a map is unique, and it allows efficient retrieval of values based on their associated keys.
Queue: A queue is a collection that follows the FIFO (First-In-First-Out) principle. Elements are added to the end and removed from the front of the queue.
Stack: A stack is a collection that follows the LIFO (Last-In-First-Out) principle. Elements are added and removed from the top of the stack.
Common Operations and Methods:
Adding and Removing Elements: Collections provide methods to add and remove elements, such as add, remove, addAll, removeAll, etc.
- Searching and Retrieving Elements: Methods like contains, get, indexOf, etc., allow searching for elements and retrieving their values.
Sorting and Ordering: Collections provide methods to sort elements using natural ordering or custom comparators, such as sort, compareTo, etc.
Iterating over Elements: Iterators or enhanced for loops can be used to iterate over the elements of a collection.
- Size and Empty Checks: Methods like size, isEmpty, etc., provide information about the size and emptiness of a collection.