DEV Community: Vidya

Collection vs Collections in Java: What's the Difference?

Vidya — Mon, 29 Jun 2026 05:43:53 +0000

When I first started learning Java, I often got confused between Collection and Collections. Their names are almost identical, but they serve completely different purposes.

Let's understand the difference with simple explanations and examples.

What is Collection?

Collection is an interface in the Java Collection Framework. It represents a group of objects (elements) and defines the basic operations that all collection classes should support.

Common methods include:
--> add()
--> remove()
--> contains()
--> size()
--> isEmpty()

Some classes that implement the Collection interface are:
=> ArrayList
=> LinkedList
=> HashSet
=> PriorityQueue

Example

import java.util.*;

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

        Collection<String> fruits = new ArrayList<>();

        fruits.add("Apple");
        fruits.add("Mango");
        fruits.add("Orange");

        System.out.println(fruits);
    }
}

Output

[Apple, Mango, Orange]

Here, Collection acts as the interface, while ArrayList provides the implementation.

What is Collections?
Collections is a utility class in Java.
It contains static methods that help perform operations on collection objects.

Some commonly used methods are:
--> sort()
--> reverse()
--> shuffle()
--> max()
--> min()
--> frequency()

Example

import java.util.*;

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

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

        numbers.add(30);
        numbers.add(10);
        numbers.add(20);

        Collections.sort(numbers);

        System.out.println(numbers);
    }
}

Output

[10, 20, 30]

Here, Collections.sort() sorts the elements in ascending order.

Easy Way to Remember:
Collection → Stores Data
Collections → Performs Operations on Data

Think of it like this:
Collection = A box that holds your items.
Collections = A toolbox with utilities to organize and manipulate those items.

Understanding Bean Scopes in Spring Boot

Vidya — Thu, 25 Jun 2026 07:09:50 +0000

Understanding Bean Scopes in Spring Boot

Spring Boot is one of the most widely used frameworks for building Java applications because it simplifies configuration, reduces boilerplate code, and helps developers create production-ready applications faster. Among the many important concepts in Spring Boot, Bean Scope plays a major role in understanding how Spring manages objects inside the application.

Bean scope tells us how many instances of a bean Spring creates, when those instances are created, and how long they remain active in the Spring container. This concept is very important because different parts of an application need different lifecycles. Some objects should be shared across the whole application, while others should be created separately for each request or each user session.

If you understand bean scopes clearly, you can design your Spring Boot application in a better way, improve performance, and avoid unnecessary memory usage.

What is a Bean?

In Spring Boot, a bean is simply an object that is created, managed, and controlled by the Spring IoC (Inversion of Control) container. Instead of creating objects manually using the new keyword, Spring creates them for us and injects them wherever they are needed.

For example, if you have a service class, repository class, or controller class, Spring can automatically create an instance of that class and manage its lifecycle. This makes the application easier to maintain and test.

A bean goes through several stages in its lifecycle:

=> Spring creates the bean instance
=> Spring injects dependencies into it
=> Spring initializes it
=> Spring uses it in the application
=> Spring destroys it when it is no longer needed

The scope of the bean decides how this lifecycle behaves.

Types of Bean Scopes in Spring Boot

Spring Boot supports different bean scopes depending on the type of application and the requirement of the object. The most commonly used scopes are Singleton, Prototype, Request, Session, and Application.

1. Singleton Scope

Singleton is the default scope in Spring Boot. This means that only one instance of the bean is created for the entire Spring container. Whenever the bean is requested, Spring returns the same object again and again.

This is the most commonly used scope because many beans in an application do not need multiple instances. For example, service classes and repository classes usually contain business logic or database access logic, and they can safely be shared across the application.

How it works:

Spring creates the bean only once when the container starts or when it is first needed.
The same bean instance is shared by all requests and all users.
This helps save memory and improves performance.

Use Case:
Service classes, repositories, helper classes, and utility classes.

Example:
If you have a UserService bean with singleton scope, every controller or component that uses UserService will receive the same object instance.

2. Prototype Scope

In Prototype scope, Spring creates a new bean instance every time the bean is requested from the container. This means that each request for the bean gives a fresh object.

This scope is useful when you need a separate object for each use, especially when the object contains temporary or user-specific data. Unlike singleton beans, prototype beans are not shared.

How it works:

Spring creates a new instance whenever the bean is requested.
Each caller gets a different object.
Spring does not fully manage the bean after creation in the same way it does for singleton beans.

Use Case:
Objects that maintain temporary state, user-specific data, or objects that should not be shared between different parts of the application.

Important Note:
Prototype beans are created by Spring, but Spring does not manage their complete lifecycle after creation. This means destruction callbacks are not automatically called in the same way as singleton beans.

3. Request Scope

Request scope is used in web applications. In this scope, Spring creates a new bean instance for every HTTP request. Once the request is completed and the response is sent back to the client, the bean is destroyed.

This scope is very useful when you want to store data that is only needed during a single request. For example, if a controller or service needs to keep track of request-specific information, request scope is a good choice.

How it works:

A new bean is created when an HTTP request starts.
The same bean is used throughout that request.
After the request finishes, the bean is removed.

Use Case:
Handling request-specific data such as request IDs, form data, or temporary processing information in web applications.

4. Session Scope

Session scope creates one bean instance per user session. The bean remains available as long as the user session is active. When the session expires or is invalidated, the bean is destroyed.

This scope is useful when you want to store information related to a particular user during their interaction with the application. Since each user has a separate session, each user gets a separate bean instance.

How it works:

When a user starts a session, Spring creates a bean for that session.
The same bean is reused for all requests made by that user during the session.
When the session ends, the bean is removed.

Use Case:
Storing user login information, shopping cart details, preferences, or any session-based data.

Example:
If one user adds items to a shopping cart, those items can be stored in a session-scoped bean so that the cart remains available until the session ends.

5. Application Scope

Application scope creates one bean instance for the entire web application. This bean is shared across all users, all sessions, and all requests within the application.

This scope is similar to singleton in many cases, but it is specifically tied to the web application context. It is useful when you want to store data that should be available globally throughout the application.

How it works:

Spring creates one bean for the whole application.
All users and sessions share the same bean.
The bean remains active as long as the application is running.

Use Case:
Application-wide configuration, shared resources, global counters, or common data that must be accessible to everyone.

Why Are Bean Scopes Important?

Bean scopes are important because they help developers control the lifecycle of objects in a Spring Boot application. Not every object should live for the same amount of time. Some objects should be shared, while others should be created separately for each request or session.

Using the correct scope provides several benefits:

1.Better memory management:
Spring creates only the number of objects that are actually needed.
2.Improved performance:
Reusing singleton beans reduces object creation overhead.
3.Proper data isolation:
Request and session scopes help keep user-specific data separate.
4.Cleaner application design:
Developers can choose the right lifecycle for each bean based on its purpose.
5.Reduced bugs:
Using the wrong scope can cause unexpected behavior, especially when dealing with shared mutable data.

For example, if you use a singleton bean to store user-specific data, different users may accidentally share the same data, which can lead to serious problems. On the other hand, if you use prototype or session scope correctly, each user or request gets its own separate object.

useMemo vs useCallback in React

Vidya — Mon, 15 Jun 2026 12:40:34 +0000

React applications re-render whenever state or props change. In most cases, React handles re-rendering efficiently. However, in large applications with complex calculations or deeply nested components, unnecessary re-renders can impact performance.

To solve this problem, React provides two optimization hooks:

useMemo – Memoizes a value.
useCallback – Memoizes a function.

Although both are used for performance optimization, they serve different purposes.

What is useMemo?

useMemo is a React Hook that stores (memoizes) the result of a calculation and reuses it on future renders until one of its dependencies changes.

Definition

useMemo prevents React from recalculating a value every time the component renders. Instead, it recalculates only when the specified dependencies change.

Syntax

const memoizedValue = useMemo(() => {
  return expensiveCalculation();
}, [dependency]);

How it Works
=> React executes the function during the first render.
=> The returned value is stored in memory.
=> On subsequent renders, React checks the dependency array.
=> If dependencies haven't changed, React returns the stored value.
=> If dependencies change, React recalculates and stores the new value.

Example Without useMemo

function ProductList({ products }) {

  const sortedProducts = products.sort((a, b) =>
    a.price - b.price
  );

  return (
    <div>
      {sortedProducts.map(product => (
        <p key={product.id}>{product.name}</p>
      ))}
    </div>
  );
}

Problem

Every time the component renders:
=> The sorting operation runs again.
=> Even if the products array hasn't changed.
=> This wastes CPU resources.

Example With useMemo

import { useMemo } from "react";

function ProductList({ products }) {

  const sortedProducts = useMemo(() => {
    return [...products].sort((a, b) =>
      a.price - b.price
    );
  }, [products]);

  return (
    <div>
      {sortedProducts.map(product => (
        <p key={product.id}>{product.name}</p>
      ))}
    </div>
  );
}

Benefit

Now sorting happens only when the products array changes.
If another state changes in the component:
=> React re-renders.
=> Sorting is skipped.
=> The stored value is reused.

What is useCallback?

useCallback is a React Hook that stores a function and returns the same function reference across renders until dependencies change.

Definition

useCallback prevents React from creating a new function every time the component renders.

Syntax

const memoizedFunction = useCallback(() => {
  // function logic
}, [dependency]);

Why Do We Need useCallback?

Consider this example:

function Parent() {

  const [count, setCount] = useState(0);

  const handleClick = () => {
    console.log("Button clicked");
  };

  return (
    <Child onClick={handleClick} />
  );
}

Whenever count changes:
--> Parent re-renders.
--> A new handleClick function is created.
--> Child receives a new function reference.
--> Child re-renders unnecessarily.

Example With useCallback

import { useCallback } from "react";" 

function Parent() {

  const [count, setCount] = useState(0);

  const handleClick = useCallback(() => {
    console.log("Button clicked");
  }, []);

  return (
    <Child onClick={handleClick} />
  );
}

Benefit
--> The same function reference is reused.
--> Child component doesn't re-render unnecessarily.
--> Performance improves.

useState vs useReducer in React

Vidya — Sat, 13 Jun 2026 07:16:24 +0000

What is useState?

useState is a React Hook that allows functional components to create and manage state. Before Hooks were introduced, state could only be managed inside class components. With useState, developers can store values such as numbers, strings, booleans, arrays, and objects directly inside functional components and update them whenever needed.

Whenever the state changes, React automatically re-renders the component and updates the UI with the latest data.

Syntax

const [state, setState] = useState(initialValue);

--> state → Current value of the state.
--> setState → Function used to update the state.
--> initialValue → Initial value assigned to the state.

Example: Counter Application

import React, { useState } from "react";

function Counter() {
  const [count, setCount] = useState(0);

  return (
    <div>
      <h2>Count: {count}</h2>

      <button onClick={() => setCount(count + 1)}>
        Increment
      </button>
    </div>
  );
}

export default Counter;

How it Works
=> useState(0) initializes the state with 0.
=> count stores the current value.
=> setCount() updates the value.
=> When the button is clicked, React re-renders the component with the updated count.

When to Use useState?

--> Counter applications
--> Show/Hide functionality
--> Theme switching
--> Simple forms
--> Managing a single piece of state

What is useReducer?

useReducer is a React Hook used for managing complex state logic. Instead of updating state directly, it uses a reducer function and actions to determine how the state should change.

It follows the same concept as Redux, where actions are dispatched and a reducer function decides the next state based on the action type.

useReducer is useful when a component has multiple state values or complex update logic.

Syntax


const [state, dispatch] = useReducer(reducer, initialState);

=> state → Current state.
=> dispatch → Function used to send actions.
=> reducer → Function that handles state updates.
=> initialState → Initial state value.

Example: Counter using useReducer

import React, { useReducer } from "react";

const initialState = { count: 0 };

function reducer(state, action) {
  switch (action.type) {
    case "increment":
      return { count: state.count + 1 };

    case "decrement":
      return { count: state.count - 1 };

    default:
      return state;
  }
}

function Counter() {
  const [state, dispatch] = useReducer(
    reducer,
    initialState
  );

  return (
    <div>
      <h2>Count: {state.count}</h2>

      <button onClick={() =>
        dispatch({ type: "increment" })
      }>
        Increment
      </button>

      <button onClick={() =>
        dispatch({ type: "decrement" })
      }>
        Decrement
      </button>
    </div>
  );
}

export default Counter;

How it Works

--> initialState stores the starting state.
--> reducer() receives the current state and action.
--> dispatch() sends an action.
--> The reducer decides how the state should change.
--> React re-renders the component with the updated state.

Real-World Example
Using useState

const [name, setName] = useState("");
const [email, setEmail] = useState("");
const [age, setAge] = useState("");

--> This is fine for a small form with a few fields.

Using useReducer

const initialState = {
  name: "",
  email: "",
  age: ""
};

function reducer(state, action) {
  switch (action.type) {
    case "UPDATE_NAME":
      return { ...state, name: action.payload };

    case "UPDATE_EMAIL":
      return { ...state, email: action.payload };

    case "UPDATE_AGE":
      return { ...state, age: action.payload };

    default:
      return state;
  }
}

--> For large forms with validations and multiple updates, useReducer keeps the code cleaner and easier to maintain.

Why Java Supports Multithreading While JavaScript is Single-Threaded?

Vidya — Fri, 12 Jun 2026 05:27:24 +0000

Why is Java Multithreaded but JavaScript Traditionally Single-Threaded?

Java and JavaScript are both popular programming languages, but they handle execution differently. One of the biggest differences is that Java supports true multithreading, while JavaScript was originally designed as a single-threaded language.

What is Multithreading?

Multithreading is the ability of a program to run multiple threads simultaneously. A thread is a lightweight unit of execution within a process. By using multiple threads, a program can perform several tasks at the same time, improving performance and responsiveness.

Why Does Java Support Multithreading?

Java was designed for building large-scale enterprise applications, desktop software, servers, and systems that often need to handle multiple tasks concurrently.

For example:

--> A banking application can process transactions while generating reports.
--> A web server can handle thousands of client requests simultaneously.
--> A desktop application can perform background tasks while keeping the user interface responsive.

Java provides built-in support for multithreading through:
=> Thread class
=> Runnable interface
=> Executor Framework
=> Concurrency utilities (java.util.concurrent)

Because of this, Java can utilize multiple CPU cores efficiently and execute threads in parallel.

Why Was JavaScript Designed as Single-Threaded?

JavaScript was originally created to run inside web browsers. Since browsers manipulate the DOM (Document Object Model), allowing multiple threads to modify the same web page simultaneously could lead to conflicts and unpredictable behavior.

To avoid these issues, JavaScript was designed with a single-threaded execution model. This means only one piece of JavaScript code runs at a time.

For example:
--> A button click event
--> Form validation
--> DOM updates

These operations execute one after another in a single thread, making browser behavior simpler and safer.

How Does JavaScript Handle Multiple Tasks?

Although JavaScript is single-threaded, it can still perform asynchronous operations using:
=> Event Loop
=> Callbacks
=> Promises
=> Async/Await

For example, while waiting for an API response, JavaScript does not block the entire application. Instead, it continues executing other code and processes the response when it arrives.

Modern JavaScript and Background Threads

Today, JavaScript can use additional threads through:
=> Web Workers (Browser)
=> Worker Threads (Node.js)

These allow heavy computations to run in the background without blocking the main thread. However, JavaScript's core execution model remains single-threaded.

Java vs JavaScript: Understanding the Key Differences

Vidya — Thu, 11 Jun 2026 13:23:45 +0000

Many beginners assume that Java and JavaScript are the same because of their similar names. However, they are completely different programming languages designed for different purposes. Understanding the differences between Java and JavaScript helps developers choose the right language for their projects.

What is Java?

Java is a high-level, object-oriented programming language developed by Oracle Corporation. It follows the principle of "Write Once, Run Anywhere" (WORA), which means Java programs can run on any platform that has a Java Virtual Machine (JVM). Java is widely used for enterprise applications, Android development, desktop software, and backend web applications.

Features of Java
=> Object-Oriented Programming (OOP)
=> Platform Independent
=> Strongly Typed Language
=> Secure and Robust
=> Multithreading Support
=> Excellent Performance with JVM

What is JavaScript?

JavaScript is a lightweight, high-level scripting language primarily used to create interactive and dynamic web pages. It was developed by Brendan Eich in 1995. JavaScript runs directly in web browsers and is one of the core technologies of web development alongside HTML and CSS.

Features of JavaScript
=> Lightweight and Interpreted
=> Dynamic Typing
=> Event-Driven Programming
=> Supports Functional and Object-Oriented Programming
=> Runs in Browsers and Servers
=> Fast Development and Deployment

Example: Java Program

public class Main {
    public static void main(String[] args) {
        System.out.println("Hello World");
    }
}

Example: JavaScript Program

console.log("Hello World");

When Should You Use Java?

Use Java when:
--> Building enterprise applications
--> Developing Android applications
--> Creating large-scale backend systems
--> Working on banking and financial software
--> Developing desktop applications
--> When Should You Use JavaScript?

Use JavaScript when:
--> Building interactive websites
--> Creating web applications
--> Developing frontend user interfaces
--> Working with frameworks like React, Angular, or Vue
--> Building server-side applications using Node.js

JavaScript Libraries and Frameworks

Vidya — Wed, 10 Jun 2026 07:28:00 +0000

JavaScript is one of the most popular programming languages used for web development. It helps developers create interactive and dynamic websites. To make development faster and easier, developers use JavaScript libraries and frameworks. Although both help in building applications, they serve different purposes.

What is a JavaScript Library?

A JavaScript library is a collection of pre-written JavaScript code that developers can use to perform common tasks. Libraries provide reusable functions and components, allowing developers to avoid writing code from scratch.

In a library, the developer controls the flow of the application and calls the library functions whenever needed.

Popular JavaScript Libraries
=> React
=> jQuery
=> Lodash
=> D3.js
=> Chart.js

Advantages of Libraries

--> Faster development
--> Reusable code
--> Easy to learn and use
--> Reduces repetitive coding

What is a JavaScript Framework?

A JavaScript framework is a complete structure that provides rules, tools, and predefined architecture for developing applications. Frameworks control the application's flow and determine how the code should be organized.

In a framework, the framework itself calls the developer's code when required. This concept is known as "Inversion of Control."

Popular JavaScript Frameworks

=> Angular
=> Vue.js
=> Next.js
=> Nuxt.js
=> Ember.js

Advantages of Frameworks
--> Organized project structure
--> Faster application development
--> Built-in tools and features
--> Easier maintenance of large applications

JavaScript libraries and frameworks help developers build modern web applications efficiently. Libraries provide specific functionalities that can be used when needed, while frameworks offer a complete structure for application development. Choosing between a library and a framework depends on the project's requirements, complexity, and development goals.

Interpreter vs Compiler: A Beginner-Friendly Guide

Vidya — Wed, 03 Jun 2026 05:29:01 +0000

When learning programming, you will often hear the terms Compiler and Interpreter. Both are used to convert human-readable source code into machine-readable code, but they work in different ways.

What is a Compiler?

A compiler is a software program that translates the entire source code into machine code before the program is executed. Once the compilation is completed, the generated executable file can run directly without needing the source code again.

How a Compiler Works?

=> Reads the entire source code.
=> Checks for syntax and semantic errors.
=> Converts the code into machine code.
=> Generates an executable file.
=> Executes the program.

Advantages of a Compiler

--> Faster program execution.
--> Errors are reported before execution.
--> Optimized machine code improves performance.

Disadvantages of a Compiler

=> Compilation can take time for large programs.
=> The program must be recompiled after every code change.

Examples of Compiled Languages
C
C++
Go
Rust

What is an Interpreter?

An interpreter is a software program that translates and executes source code line by line at runtime. It does not create a separate executable file.

How an Interpreter Works?

=> Reads one line of code.
=> Translates it into machine instructions.
=> Executes it immediately.
=> Moves to the next line.

Advantages of an Interpreter

--> Easy to test and debug code.
--> No separate compilation step is required.
--> Suitable for rapid development.

Disadvantages of an Interpreter

=> Slower execution compared to compiled programs.
=> The code must be interpreted every time it runs.

Examples of Interpreted Languages
Python
JavaScript
Ruby
PHP

Real-Life Example

Imagine you want to translate an English book into Tamil:

Compiler Approach

A translator converts the entire book first and then gives you the completed Tamil version. You can read it anytime without needing the translator again.

Interpreter Approach

A translator reads one sentence, translates it, and explains it immediately. Then moves to the next sentence.

Dependency Injection in Spring Boot

Vidya — Tue, 02 Jun 2026 05:25:57 +0000

Introduction

Dependency Injection (DI) is a design pattern used to achieve loose coupling between classes. Instead of a class creating its own objects, the required objects (dependencies) are provided by an external container. In Spring Boot, the Spring Container automatically creates and injects objects into classes.

What is Dependency Injection?

Dependency Injection is a process where the Spring Framework provides the required object to a class instead of the class creating the object itself using the new keyword. This makes the application more flexible, maintainable, and easier to test.

Without Dependency Injection
public class Car {
Engine engine = new Engine(); // Object created manually
}

In this approach, the Car class is tightly coupled with the Engine class.

With Dependency Injection
@Component
public class Engine {
}

@Component
public class Car {

@Autowired
private Engine engine;

}

Here, Spring creates the Engine object and injects it into the Car class automatically.

What is @Autowired in Spring Boot?

@Autowired is an annotation used for Dependency Injection in Spring.

It tells the Spring Container:

"This class needs an object of another class. Please create it and inject it automatically."

What happens here?

=> Spring starts the application.
=> It finds @Component on Engine.
=> Spring creates an Engine object and stores it in the Spring Container.
=> It finds @Autowired on engine.
=> Spring injects the already created Engine object into the Car class.

Internally, it works like:

Engine engine = new Engine();
Car car = new Car();
car.engine = engine;

--> But Spring does this automatically.

Why Do We Use Dependency Injection?

=> Reduces tight coupling between classes.
=> Improves code maintainability.
=> Makes unit testing easier.
=> Promotes code reusability.
=> Helps manage object creation automatically.

Auto Configuration in Spring Boot

Vidya — Mon, 01 Jun 2026 05:36:07 +0000

What is Auto Configuration in Spring Boot?

Auto Configuration is one of the most powerful features of Spring Boot. It automatically configures your application based on the dependencies available in the project. This reduces manual configuration and helps developers build applications faster.

In traditional Spring applications, developers had to create many configuration classes and bean definitions manually. Spring Boot simplifies this process through Auto Configuration.

Why Do We Use Auto Configuration?

=> Reduces boilerplate configuration code.
=> Speeds up application development.
=> Minimizes manual setup.
=> Provides sensible default configurations.
=> Makes Spring applications easier to create and maintain.

How Auto Configuration Works?

When a Spring Boot application starts:
=> Spring Boot scans the dependencies in pom.xml.
=> It checks which libraries are available.
=> Based on those libraries, it automatically creates and configures the necessary beans.
=> The application becomes ready to use with minimal configuration.

The Auto Configuration feature is enabled by the @SpringBootApplication annotation.

@SpringBootApplication
public class MyApplication {
    public static void main(String[] args) {
        SpringApplication.run(MyApplication.class, args);
    }
}

The @SpringBootApplication annotation internally includes:

@Configuration
@EnableAutoConfiguration
@ComponentScan

Here, @EnableAutoConfiguration is responsible for Auto Configuration.

Real-Life Example

Think of Auto Configuration like a new smartphone.
When you insert a SIM card:
=> The phone automatically detects the network.
=> Configures mobile settings.
=> Enables calling and internet.
---> You do not manually configure everything.

Similarly, Spring Boot detects dependencies and automatically configures the required components.

Learn REST API Easily

Vidya — Thu, 28 May 2026 06:10:07 +0000

What is REST API?
A REST API (Representational State Transfer Application Programming Interface) is a way for applications to communicate with each other using HTTP methods like GET, POST, PUT, and DELETE. It allows clients and servers to exchange data, usually in JSON format. Each resource is identified using a unique URL such as http://localhost:8080/products. REST APIs are widely used in web and mobile applications because they are simple, fast, and scalable.

When we used REST API?
We use REST APIs when different applications need to communicate and share data with each other. They are commonly used to connect frontend applications with backend servers. REST APIs are also used in web and mobile applications to perform operations like creating, reading, updating, and deleting data. They help applications work efficiently across different platforms and technologies.

Example:

Example:
http://localhost:8080/users

This is a REST API endpoint used to manage user data from the server.

localhost → Your local machine where the application runs
8080 → Port number of the server
/users → Resource that contains user information

Operations:

GET /users → Get all users
GET /users/1 → Get user with ID 1
POST /users → Add a new user
PUT /users/1 → Update user details
DELETE /users/1 → Delete user with ID 1

Image Format:

API

Vidya — Wed, 27 May 2026 07:38:26 +0000

What is API?

API stands for Application Programming Interface. It is a bridge that allows two applications to communicate and exchange data with each other. APIs are used to send requests and receive responses between frontend and backend applications. They help applications fetch, store, update, and delete data from the server or database. APIs are widely used in web applications, mobile applications, and cloud services. For example, a React frontend uses APIs to get data from a Spring Boot backend.

For example:

=> React frontend
=> Spring Boot backend
=> MySQL database

The frontend cannot directly access the database.
So it sends a request through an API, and the backend returns the response.

Simple Flow

Frontend → API → Backend → Database

Real-Time Example

Consider a food delivery app.
=> The mobile app needs restaurant data
=> The data is stored in the server/database
=> The app requests data using an API
=> The server sends the response
---> So APIs help different applications communicate with each other.

Why Do We Use API?
1.Communication Between Applications

APIs allow different applications to communicate.

Example:
React ↔ Spring Boot
Mobile App ↔ Server
Website ↔ Payment Gateway

2.To Fetch Data

APIs are used to get data from the server or database.
Example:

GET /products
   This returns all products.

3. To Send Data

APIs are used to store data in the database.
Example:

POST /products
       This adds a new product.

4. To Update Data

Example:

PUT /products/1
         This updates the product with ID 1.

5. To Delete Data

Example:

DELETE /products/1
          This deletes the product with ID 1.