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CRUD APIs using Spring Boot

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Last updated: May 25, 2026
Author: ManaCoding Team
← REST API using Spring Boot Spring MVC→

CRUD APIs in Spring Boot allow you to Create, Read, Update, and Delete data using REST endpoints. It typically uses Controller, Service, and Repository layers with Spring Data JPA.

📝 Syntax 
@RestController
@RequestMapping("/api/users")
class UserController {
}
💻 Example Program 
import org.springframework.web.bind.annotation.*;
import java.util.*;

@RestController
@RequestMapping("/api/users")
class UserController {

  private List<String> users = new ArrayList<>(Arrays.asList("John", "Alex"));

  // READ ALL
  @GetMapping
  public List<String> getAllUsers() {
    return users;
  }

  // READ BY ID
  @GetMapping("/{id}")
  public String getUser(@PathVariable int id) {
    return users.get(id);
  }

  // CREATE
  @PostMapping
  public String createUser(@RequestBody String user) {
    users.add(user);
    return "User Created";
  }

  // UPDATE
  @PutMapping("/{id}")
  public String updateUser(@PathVariable int id, @RequestBody String user) {
    users.set(id, user);
    return "User Updated";
  }

  // DELETE
  @DeleteMapping("/{id}")
  public String deleteUser(@PathVariable int id) {
    users.remove(id);
    return "User Deleted";
  }
}

// Output examples:
// GET    /api/users
// POST   /api/users
// PUT    /api/users/1
// DELETE /api/users/1
💡 What is CRUD?
  • 1 Create – add new data
  • 2 Read – retrieve data
  • 3 Update – modify data
  • 4 Delete – remove data
💡 Spring Boot CRUD Flow
  • 1 Client sends HTTP request.
  • 2 Controller handles request.
  • 3 Service processes logic.
  • 4 Repository interacts with database.
💡 HTTP Methods Used
  • 1 POST – Create
  • 2 GET – Read
  • 3 PUT – Update
  • 4 DELETE – Delete
💡 Why CRUD APIs?
  • 1 Core of backend development.
  • 2 Used in all web systems.
  • 3 Easy integration with frontend.
  • 4 Standard REST practice.
✅ Quick Summary
  • CRUD APIs handle basic data operations.
  • Spring Boot simplifies REST CRUD development.
  • Uses Controller-Service-Repository structure.
  • Follows standard HTTP methods.
❓ FAQs
What is CRUD in REST API?
Create, Read, Update, and Delete operations on data.
Which annotation is used for REST controller?
@RestController.
Which method is used to update data?
PUT method.
What is used for reading data?
GET method.
Why use CRUD APIs?
To manage data operations in applications.
🎯 Interview Questions
Q1. What is CRUD in REST API?
Answer: Create, Read, Update, and Delete operations on data.
Q2. Which annotation is used for REST controller?
Answer: @RestController.
Q3. Which method is used to update data?
Answer: PUT method.
Q4. What is used for reading data?
Answer: GET method.
Q5. Why use CRUD APIs?
Answer: To manage data operations in applications.
❓ Quiz

Which HTTP method is used for deleting data in CRUD?

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