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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.
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.
A Collection is aninterface in Java. It is present in thepackage named java.util. It can be understood as a single unit with a group or a set of objects. It is an interface that allclasses 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.
"Collections" is a class in Java. Specifically, it is a utility class in the package namedjava.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, likesearching or sorting.
All the methods in "Collections" are static.Staticis 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
Parameters
Collections
Collection
Meaning
Collections 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.
Class
All the methods in "Collections" are static.
After Java 8, the "Collection" interface got static, default, andabstract methods. An abstract method is a method inside an abstract class that was declared with the abstract keywordbut lacked a definition.
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); } }
You can also try this code with Online Java Compiler
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); } }
You can also try this code with Online Java Compiler
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 javaand iterable interface in java.