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.
Similarly, Here is the example of Java Collection Framework with comment and explanation:
ArrayList:
import java.util.ArrayList;
public class ArrayListExample {
public static void main(String[] args) {
// Create an ArrayList to store integers
ArrayList<Integer> numbers = new ArrayList<>();
// Add elements to the ArrayList
numbers.add(10);
numbers.add(20);
numbers.add(30);
// Access and print elements from the ArrayList
System.out.println("Element at index 0: " + numbers.get(0));
System.out.println("Size of the ArrayList: " + numbers.size());
// Remove an element from the ArrayList
numbers.remove(1);
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
- 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.
- 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.
- 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.
- 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) {
// Creating a List using the List interface
List<String> names = new ArrayList<>();
// Adding elements to the list
names.add("Alice");
names.add("Bob");
names.add("Charlie");
names.add("Alice"); // Lists allow duplicates
// Accessing elements using for-each loop
System.out.println("Names in the list:");
for (String name : names) {
System.out.println(name);
}
// Accessing elements using index
System.out.println("\nAccessing element at index 2: " + names.get(2));
// Checking if the list contains a specific element
if (names.contains("Alice")) {
System.out.println("\nThe list contains 'Alice'.");
}
// Removing an element
names.remove("Bob");
System.out.println("\n'Bob' is removed from the list.");
// Displaying the list after removal
System.out.println("Updated list:");
for (String name : names) {
System.out.println(name);
}
// Getting the size of the list
System.out.println("\nSize of the list: " + names.size());
// Clearing the list
names.clear();
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) {
// Creating a Queue using the Queue interface
Queue<String> waitingQueue = new LinkedList<>();
// Adding elements to the queue
waitingQueue.offer("Customer 1");
waitingQueue.offer("Customer 2");
waitingQueue.offer("Customer 3");
waitingQueue.offer("Customer 4");
// Displaying the elements in the queue
System.out.println("Customers in the waiting queue:");
for (String customer : waitingQueue) {
System.out.println(customer);
}
// Removing elements and processing the queue
System.out.println("\nProcessing the waiting queue:");
while (!waitingQueue.isEmpty()) {
String customer = waitingQueue.poll();
System.out.println("Processing: " + customer);
}
// Check if the queue is empty after processing
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) {
// Creating a Set using the Set interface
Set<String> uniqueNames = new HashSet<>();
// Adding elements to the set
uniqueNames.add("Alice");
uniqueNames.add("Bob");
uniqueNames.add("Alice"); // Duplicate element - won't be added
// Displaying the elements in the set
System.out.println("Unique names in the set:");
for (String name : uniqueNames) {
System.out.println(name);
}
// Checking if the set contains a specific element
if (uniqueNames.contains("Bob")) {
System.out.println("\nThe set contains 'Bob'.");
}
// Removing an element
uniqueNames.remove("Alice");
System.out.println("\n'Alice' is removed from the set.");
// Displaying the set after removal
System.out.println("Updated set:");
for (String name : uniqueNames) {
System.out.println(name);
}
// Getting the size of the set
System.out.println("\nSize of the set: " + uniqueNames.size());
// Clearing the set
uniqueNames.clear();
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) {
// Creating a Map using the Map interface
Map<Integer, String> studentMap = new HashMap<>();
// Adding key-value pairs to the map
studentMap.put(1, "Alice");
studentMap.put(2, "Bob");
studentMap.put(3, "Charlie");
studentMap.put(4, "Alice"); // Duplicate value for a different key
// Displaying the elements in the map
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());
}
// Checking if the map contains a specific key
if (studentMap.containsKey(2)) {
System.out.println("\nThe map contains the student with ID 2.");
}
// Checking if the map contains a specific value
if (studentMap.containsValue("Bob")) {
System.out.println("The map contains a student named 'Bob'.");
}
// Removing an element by key
studentMap.remove(1);
System.out.println("\nStudent with ID 1 is removed from the map.");
// Displaying the map after removal
System.out.println("Updated map:");
for (Map.Entry<Integer, String> entry : studentMap.entrySet()) {
System.out.println("Student ID: " + entry.getKey() + ", Name: " + entry.getValue());
}
// Getting the size of the map
System.out.println("\nSize of the map: " + studentMap.size());
// Clearing the map
studentMap.clear();
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.
Types of Programming Framework?
- 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).
- 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.
- 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.
- 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.
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.
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Conclusion
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.
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