Java Code Generator (Free AI Tool)

Plain English:
"Create a Spring Boot REST controller for managing products
with GET all, GET by ID, POST create, and DELETE operations.
Include validation, exception handling, and proper HTTP status codes."

package com.example.api.controller;

import com.example.api.model.Product;
import com.example.api.service.ProductService;
import com.example.api.exception.ResourceNotFoundException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import javax.validation.Valid;
import java.util.List;

/**
 * REST controller for managing product resources.
 * 
 * Provides CRUD operations for products with proper validation
 * and exception handling.
 * 
 * @author AI Generated
 * @version 1.0
 */
@RestController
@RequestMapping("/api/v1/products")
public class ProductController {
    
    private final ProductService productService;
    
    /**
     * Constructor injection for ProductService dependency.
     * 
     * @param productService Service layer for product operations
     */
    @Autowired
    public ProductController(ProductService productService) {
        this.productService = productService;
    }
    
    /**
     * Retrieve all products.
     * 
     * @return List of all products with 200 OK status
     */
    @GetMapping
    public ResponseEntity<List<Product>> getAllProducts() {
        List<Product> products = productService.findAll();
        return ResponseEntity.ok(products);
    }
    
    /**
     * Retrieve product by ID.
     * 
     * @param id Product identifier
     * @return Product with 200 OK status
     * @throws ResourceNotFoundException if product not found
     */
    @GetMapping("/{id}")
    public ResponseEntity<Product> getProductById(@PathVariable Long id) {
        Product product = productService.findById(id)
            .orElseThrow(() -> new ResourceNotFoundException(
                "Product not found with id: " + id
            ));
        return ResponseEntity.ok(product);
    }
    
    /**
     * Create new product.
     * 
     * @param product Product data with validation
     * @return Created product with 201 CREATED status
     */
    @PostMapping
    public ResponseEntity<Product> createProduct(
            @Valid @RequestBody Product product) {
        Product created = productService.save(product);
        return ResponseEntity.status(HttpStatus.CREATED).body(created);
    }
    
    /**
     * Delete product by ID.
     * 
     * @param id Product identifier
     * @return 204 NO CONTENT status
     * @throws ResourceNotFoundException if product not found
     */
    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteProduct(@PathVariable Long id) {
        if (!productService.existsById(id)) {
            throw new ResourceNotFoundException(
                "Cannot delete. Product not found with id: " + id
            );
        }
        productService.deleteById(id);
        return ResponseEntity.noContent().build();
    }
}

Plain English:
"Create a JPA entity for User with id, email, name, and creation date.
Include validation for email format and non-null name.
Add equals, hashCode, and toString methods."

package com.example.api.model;

import javax.persistence.*;
import javax.validation.constraints.Email;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.Size;
import java.time.LocalDateTime;
import java.util.Objects;

/**
 * User entity representing application users.
 * 
 * JPA entity with validation constraints and proper equals/hashCode.
 * 
 * @author AI Generated
 * @version 1.0
 */
@Entity
@Table(name = "users", 
       uniqueConstraints = @UniqueConstraint(columnNames = "email"))
public class User {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    @NotBlank(message = "Email is required")
    @Email(message = "Email must be valid format")
    @Column(nullable = false, unique = true, length = 100)
    private String email;
    
    @NotBlank(message = "Name is required")
    @Size(min = 2, max = 50, message = "Name must be between 2 and 50 characters")
    @Column(nullable = false, length = 50)
    private String name;
    
    @Column(name = "created_at", nullable = false, updatable = false)
    private LocalDateTime createdAt;
    
    /**
     * Default constructor required by JPA.
     */
    public User() {
        this.createdAt = LocalDateTime.now();
    }
    
    /**
     * Constructor with required fields.
     * 
     * @param email User email address
     * @param name User full name
     */
    public User(String email, String name) {
        this();
        this.email = email;
        this.name = name;
    }
    
    // Getters and Setters
    
    public Long getId() {
        return id;
    }
    
    public void setId(Long id) {
        this.id = id;
    }
    
    public String getEmail() {
        return email;
    }
    
    public void setEmail(String email) {
        this.email = email;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    
    public LocalDateTime getCreatedAt() {
        return createdAt;
    }
    
    /**
     * Equals based on id (primary key).
     */
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        User user = (User) o;
        return Objects.equals(id, user.id);
    }
    
    /**
     * HashCode based on id (primary key).
     */
    @Override
    public int hashCode() {
        return Objects.hash(id);
    }
    
    /**
     * String representation for debugging.
     */
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", email='" + email + '\'' +
                ", name='" + name + '\'' +
                ", createdAt=" + createdAt +
                '}';
    }
}