Collection Framework in Java

Collection Framework in Java

Java Collection Framework 

Collection Framework in Java includes collections of various interfaces and collections, which helps to process and store the data efficiently. Similarly, in simple words, we can say that the Collection Framework in Java is generally like a container that stores & groups multiple units of data in a single unit. For example, we can say that:- a jar of candies, a list of various names & a bunch of grapes etc.

Java Collection Framework provides various interfaces like – Queue, List, Deque, set etc. Similarly, these framework has several classes which help in processing & storing the data efficiently. Therefore, this framework has many useful classes which have tons of important functions & make the working of a programmer super easy.

Java Collection Framework

Similarly, Here is the example of Java Collection Framework with comment and explanation:


import java.util.ArrayList;

public class ArrayListExample {
     public static void main(String[] args) {

         ArrayList<Integer> numbers = new ArrayList<>();


         System.out.println("Element at index 0: " + numbers.get(0));
         System.out.println("Size of the ArrayList: " + numbers.size());

         System.out.println("Size after removing an element: " + numbers.size());

Explanation: In this example, we create an ArrayList to store integers. We add elements, access elements by their index, and remove an element. ArrayList is a dynamic array that automatically resizes itself when elements are added or removed.

Advantages of Java Collection Framework

Advantages of Java Collection Framework
  1. Reduces Programming efforts:- With this a programmer doesn’t worry about the design of the program rather he can fully focus on its best use in the program. Therefore, the programmer can easily focus on the logic of business rather than designing our collection APIs. 
  2. Increases speed & quality of the program:- Increases the speed & quality of the program by the implementation of useful algorithms & data structures because, in this case, the programmer need not think about the best implementation of the specific data structure. Similarly, he can use the best implementation to boost the performance of this program. 
  3. Better Quality:- Using the core collection classes which are very well tested & increases the quality of the program rather than using any home-developed data structures. 
  4. Facilitates code reusability:– This provides common interfaces & classes that will be used in various types of collections.

What you should learn in Java Collections?

List Interface 

The list interface in Java helps to store the ordered collection. Similarly, this is an ordered collection of objects in which the developer can store the duplicate values. Therefore, the implementation classes of List Interfaces are – Linkedlist, ArrayList, Vector and Stack. Similarly, out of them all ArrayList & LinkedList are the most widely used in Java.

For example:- 

import java.util.ArrayList;
import java.util.List;

public class ListExample {
    public static void main(String[] args) {

        List<String> names = new ArrayList<>();


        System.out.println("Names in the list:");
        for (String name : names) {

        System.out.println("\nAccessing element at index 2: " + names.get(2));

        if (names.contains("Alice")) {
            System.out.println("\nThe list contains 'Alice'.");

        System.out.println("\n'Bob' is removed from the list.");

        System.out.println("Updated list:");
        for (String name : names) {

        System.out.println("\nSize of the list: " + names.size());

        System.out.println("List cleared. Is the list empty? " + names.isEmpty());

This example demonstrates the basic usage of the List interface with an ArrayList. Similarly, it includes adding elements, accessing elements by index, checking for the existence of an element, removing elements, getting the size, and clearing the list.

Queue Interface

Queue Interface holds the rule of FIFO (First In First Out). Similarly, a queue is a list of objects that represent limited use of the elements inserted at the end of the list and elements removed from the beginning of the list.

For Example

import java.util.LinkedList;
import java.util.Queue;

public class QueueExample {
    public static void main(String[] args) {

        Queue<String> waitingQueue = new LinkedList<>();

        waitingQueue.offer("Customer 1");
        waitingQueue.offer("Customer 2");
        waitingQueue.offer("Customer 3");
        waitingQueue.offer("Customer 4");

        System.out.println("Customers in the waiting queue:");
        for (String customer : waitingQueue) {

        System.out.println("\nProcessing the waiting queue:");
        while (!waitingQueue.isEmpty()) {
            String customer = waitingQueue.poll();
            System.out.println("Processing: " + customer);

        System.out.println("\nIs the queue empty? " + waitingQueue.isEmpty());

This example showcases the basic usage of the Queue interface using a LinkedList as an implementation. Therefore, it demonstrates adding elements to the queue using offer(), iterating over the elements, removing elements from the front of the queue using poll(), and checking whether the queue is empty using isEmpty().

Set in Java Interface

 The Set in Java interface contains the implementation of the mathematical set. Similarly, we can say that this is an unordered collection of elements in which duplicate values can’t be stored. 

For example –

import java.util.HashSet;
import java.util.Set;

public class SetExample {
    public static void main(String[] args) {

        Set<String> uniqueNames = new HashSet<>();


        System.out.println("Unique names in the set:");
        for (String name : uniqueNames) {

        if (uniqueNames.contains("Bob")) {
            System.out.println("\nThe set contains 'Bob'.");

        System.out.println("\n'Alice' is removed from the set.");

        System.out.println("Updated set:");
        for (String name : uniqueNames) {

        System.out.println("\nSize of the set: " + uniqueNames.size());

        System.out.println("Set cleared. Is the set empty? " + uniqueNames.isEmpty());

This example demonstrates the basic usage of the Set interface with a HashSet. Similarly, it includes adding elements (where duplicates are not allowed), iterating over the set, checking for the existence of an element, removing elements, getting the size, and clearing the set.

Map Interface in Java 

The Map interface in Java is a part of the Java Collections Framework and is used to represent a collection of key-value pairs. Therefore, each key is associated with a corresponding value, and you can use the key to retrieve the associated value. Similarly, the Map interface is generic, meaning you can specify the types for both the keys and values when you declare a Map instance.

For Example        

import java.util.HashMap;
import java.util.Map;

public class MapExample {
    public static void main(String[] args) {

        Map<Integer, String> studentMap = new HashMap<>();

        studentMap.put(1, "Alice");
        studentMap.put(2, "Bob");
        studentMap.put(3, "Charlie");
        studentMap.put(4, "Alice"); 

        System.out.println("Students in the map:");
        for (Map.Entry<Integer, String> entry : studentMap.entrySet()) {
            System.out.println("Student ID: " + entry.getKey() + ", Name: " + entry.getValue());

        if (studentMap.containsKey(2)) {
            System.out.println("\nThe map contains the student with ID 2.");

        if (studentMap.containsValue("Bob")) {
            System.out.println("The map contains a student named 'Bob'.");

        System.out.println("\nStudent with ID 1 is removed from the map.");

        System.out.println("Updated map:");
        for (Map.Entry<Integer, String> entry : studentMap.entrySet()) {
            System.out.println("Student ID: " + entry.getKey() + ", Name: " + entry.getValue());

        System.out.println("\nSize of the map: " + studentMap.size());

        System.out.println("Map cleared. Is the map empty? " + studentMap.isEmpty());

This example demonstrates the basic usage of the Map interface with a HashMap. Therefore, it includes adding key-value pairs, iterating over the map, checking for the existence of keys/values, removing elements by key, getting the size, and clearing the map.

What is a Framework?

A framework is a set of programming tools that provide ready-made structures to build reliable systems & software. Coding will be tough for sometimes even, for the IT professionals also. Similarly, the development process will go from various debugging frustrations, various tough tasks & errors. Therefore, various development teams prefer to use frameworks to save their time & effort.

What is Framework?

Types of Programming Framework?

  1. Web Framework – Web Frameworks generally relate to the development of Web applications by using web resources & web APIs. So, developers can use various web frameworks for the front end (What a website looks) used in the Back end (How a website works) & front end (How a website looks).
  2. Mobile App Development Framework– A mobile App Development framework ( mobile development framework ) helps the developer in the development of mobile applications for the specific environment, hybrid or cross platforms. 
  3. Content Management Framework – A Content Management Framework ( CMS ) enables the developer to build, Organize, deliver, including blog posts, modify the content or other online solutions. Therefore, a content management system is a tool that delivers the reusable components for managing website content & sharing aspects of the CMS & web app framework. 
  4. Data Science Framework – TensorFlow is an open source & free Python library mainly used for Machine Learning and Artificial Intelligence which was developed by Google. Similarly, this contains a flexible ecosystem of tools, community resources & libraries. Similarly, this will help a developer to deploy & build ML-powered applications. 
Types of Programming Frameworks

Frequently Asked Questions (FAQs)

What is a collection in Java?

A collection in Java is a set of objects that represents a group of objects. Therefore, we can also say that collection in Java is the root interface of collection which provides many interfaces and classes to represent a group of objects in a single unit.

What are the types of collections?

  • Queus
  • Bags
  • Hash Tables
  • Stacks
  • Dictionaries
  • Lists

Why Collection is used in Java?

In Java collection is used to manipulate, retrieve, store & provide aggregate data.

How Many Java collections are there?

There are six Java collection interfaces are there which are mainly used by the developers. These are – collections, map, sets, list, sortedset, sortedmap.

What are the differences between collections and collection?

Collection and Collections both are used by the developers in Java programming. Similarly, collection is an interface in Java and Collections is a utility class in Java.

You can get more information regarding Java Programming Language from:-


A collection in Java simply means a single unit that contains a group of objects. Similarly, in case if you want to get more in-depth knowledge about Java programming then you can choose GTB Computer Education, Jalandhar. At the same time, we have been in the field of Computer training for the last 23+ years & provide fully practical-based training to our students on live projects.
So, whenever in future you decide to go for any programming languages like – Java, Python, Machine Learning, PHP, Mern Stack, Mean Stack, React, Angular, etc. you can choose us. Attend a free demo class then compare & decide.

Back To Top