Code360 powered by Coding Ninjas X Naukri.com. Code360 powered by Coding Ninjas X Naukri.com
Table of contents
1.
Introduction
2.
What is Collection in Java?
2.1.
Declaration of Collection
2.2.
Need for Collection
3.
What are Collections in Java?
3.1.
Syntax of Collections in Java
3.2.
Need for Collections
4.
Collections vs Collection in Java
5.
Implementation of Collection and Collections in Java
5.1.
Implementation in Java
5.2.
java
6.
Java Program to Demonstrate the Difference Between Collection and Collections
6.1.
Implementation in Java
6.2.
java
6.3.
Explanation
7.
Frequently Asked Questions
7.1.
Why are collections used in Java?
7.2.
How to use stream in collection?
7.3.
What is the difference between streams and collections?
7.4.
What is the process of collections?
8.
Conclusion
Last Updated: Jun 11, 2024
Medium

Difference Between Collection and Collections in Java

Author Amit Singh
0 upvote
Master Power BI using Netflix Data
Speaker
Ashwin Goyal
Product @
18 Jun, 2024 @ 01:30 PM

Introduction

A Collection is an interface in Java that is present in java.util.package whereas Collections is a class in Java that is found in java.util.package that defines several.

difference between collection and collections

This article focuses on an important class called Collections and an interface called Collection in Java programming language. Their name is almost similar, but there is a difference. In this article, we will see the difference between Collection and Collections in Java. Let's dive into the article to learn more about the topic.

Refer this to know about,  loop and while loop

What is Collection in Java?

A Collection is an interface in Java. It is present in the package named java.util. It can be understood as a single unit with a group or a set of objects. It is an interface that all classes in the collection framework must implement. The Collection framework depends on the Collection interface. You can also understand it as a framework that gives you an architecture to manipulate as well as store a group or set of objects. 

The Collection framework has many interfaces like 

It also has some classes, for example 

Declaration of Collection

public interface Collection extends Iterable

Need for Collection

Below are some points that highlight the need for Collection in Java.

  • With the help of Collection, you can store multiple elements in a single entity which makes it easier to work with groups of related items.
     
  • The collection provides an abstraction for various collection classes, such as ArrayList, LinkedList, and more.
     
  • The iterator method in Collection allows you to access the elements sequentially.
     
  • To do operations like union, intersection, and difference, we needed collection to do such operations.
     

Must Read Difference between ArrayList and LinkedList

Get the tech career you deserve, faster!
Connect with our expert counsellors to understand how to hack your way to success
User rating 4.7/5
1:1 doubt support
95% placement record
Akash Pal
Senior Software Engineer
326% Hike After Job Bootcamp
Himanshu Gusain
Programmer Analyst
32 LPA After Job Bootcamp
After Job
Bootcamp

What are Collections in Java?

"Collections" is a class in Java. Specifically, it is a utility class in the package named java.util. A utility class defines a set of methods that carry out frequent or repetitive tasks. You can use the "Collections" class to perform different operations on a Collection, like searching or sorting.

All the methods in "Collections" are static. Static is a keyword in Java used for memory management. It is used for a constant variable or method that applies to each instance of a class.

It has different methods for different operations. For example,

  • You can use the sort() method to sort a Collection, 
     
  • the min() method to find the minimum value in the Collection, and 
     
  • the max() method to find the maximum value in the Collection. 
     

Syntax of Collections in Java

public class Collections extends Object

Need for Collections

Below are some points that highlight the need for Collections in Java.

  • Collections class provides a set of utility methods that offer sorting, searching, reversing, copying, and filling collections. Utility methods provide efficient ways to do common operations on collections.
     
  • Collections are useful in implementations of various algorithm such as performing binary search binarySearch(), max(), and min().
     
  • The collections class provides methods to create immutable collections.
     
  • Collections class provides singleton collections which are useful in that case where you need a collection with only one element, such as in APIs.

Collections vs Collection in Java

ParametersCollectionsCollection
MeaningCollections is a class Collection is an interface
Definition"Collections" is actually a utility in java that is in the java.util.package."Collection" is an interface class in java that is also in the java.util.package.
Operations"Collections" is a set of methods you can use to perform different operations on a collection.The "Collection" can be understood as a single unit with a group or a set of objects. 
ClassAll the methods in "Collections" are static.After Java 8, the "Collection" interface got static, default, and abstract methods. An abstract method is a method inside an abstract class that was declared with the abstract keyword but lacked a definition.
SupportsThe "Collections" class extends the Object class.The "Collection" interface extends the Iterable interface.

Must See, IEnumerable vs IQueryable

Implementation of Collection and Collections in Java

Now, let's check out an example to understand the use of the "Collection" interface and "Collections" Class.

Implementation in Java

  • java

java

import java.io.*;
import java.util.*;

class HelloWorld {
public static void main(String[] args) {
/* First, we will create a list of String type. */
List<String> testarr = new ArrayList<String>();

/* Secondly, we will add elements to the "testarr." *?
testarr.add("Coding");
testarr.add("Ninjas");
testarr.add("Code");
testarr.add("Studio");

/*
Thirdly, we will print the elements of "testarr."
We have not performed any operations yet.
*/

System.out.println("The elements of List (testarr) before performing any operations are: ");
System.out.println(testarr);
System.out.println();

System.out.println("Now, the elements of the List (testarr) after performing the 'addAll()' operation are:");

/*
Now, we will try to add elements using the collections to the collection named "testarr."
*/
Collections.addAll(testarr, "can", "help", "you", "reach", "your", "goal");

/* Then, we will print the testarr after trying the addAll() method using "Collections". */
System.out.println(testarr);
System.out.println();

System.out.println("Now, the elements of the List (testarr) after performing the 'sort()' operation are:");

// Lastly, we will try to sort the elements using the Collections.sort method.
Collections.sort(testarr);

// Then, we will print the collection named "testarr."
System.out.println(testarr);
}
}

 

Output

output

Java Program to Demonstrate the Difference Between Collection and Collections

The following program demonstrates the difference between them:

Implementation in Java

  • java

java

import java.io.*;
import java.util.*;
class HelloWorld {
public static void main(String[] args) {
// first we will create a collection
Collection<String> testing = new ArrayList<>();

// Secondly, we will add elements to the collection
testing.add("Reliance");
testing.add("Adani");
testing.add("AsianPaint");

// Using Collections utility class
System.out.println("Collection is : " + testing);

// Sort the collection by using Collections.sort()
Collections.sort((ArrayList<String>) testing);
System.out.println("Sorted collection is : " + testing);

// Rverse the collection by using Collections.reverse()
Collections.reverse((ArrayList<String>) testing);
System.out.println("Reversed collection is : " + testing);
}
}

 

Output

Output

Explanation

In the above code, we created a Collection object named testing. Then we added some elements to the collection. Next, we demonstrated the usage of the Collections utility class. Then by using the Collections class, we performed operations like sorting and reversing, and we printed the output accordingly.

Frequently Asked Questions

Why are collections used in Java?

Collections in Java provide a framework for storing and manipulating groups of objects efficiently. They offer various data structures like lists, sets, and maps, enabling dynamic storage, easy data manipulation, and algorithms for common operations like searching, sorting, and iteration.

How to use stream in collection?

To use a stream in a collection, call the stream() method on the collection. For example, you can use collection.stream().filter(...).map(...).collect(...) to perform operations like filtering, mapping, and collecting results. Streams provide a functional approach to process data in a collection.

What is the difference between streams and collections?

Collections store and manage data, supporting various data structures. Streams, on the other hand, are designed for processing data. They offer a high-level, functional approach to operations like filtering, mapping, and reducing without altering the original data structure. Streams enable parallel processing and lazy evaluation, enhancing performance and efficiency.

What is the process of collections?

The process of collections involves creating, adding, retrieving, updating, and removing elements from data structures like lists, sets, or maps in Java.

Conclusion

In this article, we have studied an important class called Collections and an interface known as Collection in Java programming language. 

We hope that this article has provided you with the help to enhance your knowledge of the difference between Collection and Collections in JAVA. If you would like to learn more, check out our articles on mathround in java and iterable interface in java.

Refer to our guided paths on Coding Ninjas Studio to learn more about DSA, Competitive Programming, JavaScript, System Design, etc. Enroll in our courses and refer to the mock test and problems available; take a look at the interview experiences and interview bundle for placement preparations.

Do upvote our blog to help other ninjas grow.

Merry Learning!

Previous article
The java.lang Package
Next article
Decision Statements in Java
Live masterclass