Here’s a step-by-step example of a CRUD (Create, Read, Update, Delete) operation using Java Spring Boot with PostgreSQL, updated for 2025 best practices.

✅ Tools & Technologies:

🔧 Step 1: Create a Spring Boot Project

Use Spring Initializr:

  • Project: Maven
  • Language: Java
  • Spring Boot: 3.2.x
  • Dependencies: -Spring Web -Spring Data JPA -PostgreSQL Driver -Spring Boot DevTools

Generate and unzip the project.

🗂️ Step 2: Configure application.properties

In src/main/resources/application.properties:

spring.application.name=java-crud-postgre-sql
spring.datasource.url=jdbc:postgresql://localhost:5432/database_name
spring.datasource.username=DB user name
spring.datasource.password=DB password here
spring.datasource.driver-class-name=org.postgresql.Driver

spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect

server.port=8080

Ensure the PostgreSQL server is running and the database database_name exists.

🧱 Step 3: Create an Entity Class 

package com.example.demo.model;

import jakarta.persistence.*;

@Entity
public class Product {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;
    private Double price;

    // Getters and Setters
}

📦 Step 4: Create a Repository 

package com.example.demo.repository;

import com.example.demo.model.Product;
import org.springframework.data.jpa.repository.JpaRepository;

public interface ProductRepository extends JpaRepository {
}

⚙️ Step 5: Create a Service Layer (Optional but Best Practice) 

package com.example.demo.service;

import com.example.demo.model.Product;
import com.example.demo.repository.ProductRepository;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Optional;

@Service
public class ProductService {

    private final ProductRepository repo;

    public ProductService(ProductRepository repo) {
        this.repo = repo;
    }

    public List getAll() {
        return repo.findAll();
    }

    public Product save(Product product) {
        return repo.save(product);
    }

    public Optional getById(Long id) {
        return repo.findById(id);
    }

    public void deleteById(Long id) {
        repo.deleteById(id);
    }

    public Product update(Long id, Product updatedProduct) {
        return repo.findById(id).map(product -> {
            product.setName(updatedProduct.getName());
            product.setPrice(updatedProduct.getPrice());
            return repo.save(product);
        }).orElseThrow(() -> new RuntimeException("Product not found"));
    }
}

🌐 Step 6: Create a REST Controller 

package com.example.demo.controller;

import com.example.demo.model.Product;
import com.example.demo.service.ProductService;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/api/products")
public class ProductController {

    private final ProductService service;

    public ProductController(ProductService service) {
        this.service = service;
    }

    @GetMapping
    public List getAll() {
        return service.getAll();
    }

    @GetMapping("/{id}")
    public ResponseEntity getById(@PathVariable Long id) {
        return service.getById(id)
                .map(ResponseEntity::ok)
                .orElse(ResponseEntity.notFound().build());
    }

    @PostMapping
    public Product create(@RequestBody Product product) {
        return service.save(product);
    }

    @PutMapping("/{id}")
    public Product update(@PathVariable Long id, @RequestBody Product product) {
        return service.update(id, product);
    }

    @DeleteMapping("/{id}")
    public ResponseEntity delete(@PathVariable Long id) {
        service.deleteById(id);
        return ResponseEntity.noContent().build();
    }
}

🧪 Step 7: Test with Postman or curl

POST /api/products – Create
GET /api/products – Read all
GET /api/products/{id} – Read one
PUT /api/products/{id} – Update
DELETE /api/products/{id} – Delete

GitHub repo: https://github.com/saifcse06/java-crud-postgre-sql/

If you have any doubts or suggestions, let me know in the comments section. Happy coding!