What is the use of the @Entity annotation in Spring Data JPA?
A) To map a Java class to a database table
B) To define a primary key for the entity
C) To specify a repository interface
D) To indicate that a class is a Spring bean
Answer:
A) To map a Java class to a database table
Explanation:
The @Entity annotation in Spring Data JPA is used to map a Java class to a database table. This annotation is part of the JPA (Java Persistence API) specification and is applied to classes that represent database entities.
For example:
@Entity
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
private String email;
// Getters and setters
}
In this example, the User class is annotated with @Entity, indicating that it is a JPA entity. The fields of the class correspond to the columns of the database table, and the class represents the table’s rows. The @Id annotation is used to specify the primary key, and the @GeneratedValue annotation indicates that the primary key value will be generated automatically.
The @Entity annotation is fundamental in JPA, as it establishes the link between the object-oriented domain model and the relational database.