@Data

@Data is Lombok’s most powerful convenience annotation. A single @Data on a class generates a complete set of “data class” members at once, making it the go-to choice for DTOs and value objects. Because it bundles so much, it also has the most caveats — especially around JPA entities.

What @Data bundles

@Data is shorthand for applying five annotations together:

Bundled annotation	What it generates
@Getter	a getter for every field
@Setter	a setter for every non-final field
@ToString	a toString() over all fields
@EqualsAndHashCode	equals() and hashCode() over all fields
@RequiredArgsConstructor	a constructor for final and @NonNull fields

So this concise class:

import lombok.Data;

@Data
public class CustomerDto {
    private Long id;
    private String name;
    private String email;
}

is functionally equivalent to:

public class CustomerDto {
    private Long id;
    private String name;
    private String email;

    public CustomerDto() {}                       // no required fields → no-arg ctor

    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public String getEmail() { return email; }
    public void setEmail(String email) { this.email = email; }

    @Override public String toString() {
        return "CustomerDto(id=" + id + ", name=" + name + ", email=" + email + ")";
    }
    @Override public boolean equals(Object o) { /* compares all fields */ }
    @Override public int hashCode() { /* hashes all fields */ }
}

Note: @Data only adds a @RequiredArgsConstructor. If every field is non-final and non-@NonNull, that constructor is a no-arg constructor. To also get an all-args constructor, add @AllArgsConstructor explicitly.

When to use it

@Data shines on plain, mutable data carriers where you want the full accessor/identity/string suite:

• Request and response DTOs in your web layer.
• Configuration property holders bound from application.yml.
• Internal value objects that are compared by their contents.

@RestController
@RequestMapping("/api/customers")
public class CustomerController {

    @PostMapping
    public CustomerDto create(@RequestBody CustomerDto dto) {
        // dto.getName(), dto.getEmail() all available via @Data
        return dto;
    }
}

For immutable DTOs, prefer Java records or pair @Getter with @Builder instead of @Data.

Cautions for JPA entities

Do not put @Data on JPA entities. The bundled @EqualsAndHashCode and @ToString operate over all fields, which causes real bugs in persistence:

// AVOID — @Data on an entity is dangerous
@Entity
@Data
public class Author {
    @Id @GeneratedValue
    private Long id;
    private String name;

    @OneToMany(mappedBy = "author")
    private List<Book> books;   // toString + equals will traverse this
}

Three concrete problems arise:

1. Infinite recursion / lazy-loading blow-ups. toString() walks books, each Book.toString() walks back to its Author, and so on. With bidirectional relationships this either loops forever or triggers unwanted lazy loads (and LazyInitializationException outside a session).
2. Broken equality. equals()/hashCode() over a mutable, generated id mean an entity’s hash changes after it is persisted, corrupting HashSet/HashMap membership.
3. Unwanted setters. @Data generates setters for the primary key and every field, undermining encapsulation of managed state.

The correct entity pattern uses focused annotations:

@Entity
@Getter
@Setter
@ToString(exclude = "books")
@EqualsAndHashCode(onlyExplicitlyIncluded = true)
public class Author {
    @Id @GeneratedValue
    @EqualsAndHashCode.Include
    private Long id;
    private String name;

    @OneToMany(mappedBy = "author")
    private List<Book> books;
}

The reasoning behind each choice is detailed in @EqualsAndHashCode & @ToString and Lombok Best Practices.

Warning: The single biggest Lombok mistake in Spring Boot projects is annotating an @Entity with @Data. Reserve @Data for DTOs and value objects.

Related Topics

• @Getter & @Setter
• Constructor Annotations
• @EqualsAndHashCode & @ToString
• Records as DTOs
• Lombok Best Practices