Does entity class in hibernate require no arg constructor?

ghz 9months ago ⋅ 125 views

Yes, entity classes in Hibernate typically require a no-argument constructor (i.e., a constructor with no parameters). This is because Hibernate uses reflection to instantiate objects of entity classes when retrieving data from the database. If an entity class does not have a no-argument constructor, Hibernate may encounter issues when attempting to instantiate objects of that class.

When Hibernate retrieves data from the database and attempts to create instances of entity classes, it needs a way to initialize the objects. Having a no-argument constructor allows Hibernate to instantiate objects without requiring any constructor arguments.

Here's an example of a simple entity class with a no-argument constructor:

@Entity
@Table(name = "employee")
public class Employee {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    private String name;
    
    // No-argument constructor
    public Employee() {
        // Default constructor
    }
    
    // Getters and setters
    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;
    }
}

In this example, the Employee class has a no-argument constructor explicitly defined. This constructor allows Hibernate to create instances of the Employee class when retrieving data from the database.

If an entity class does not explicitly define a constructor, Java provides a default no-argument constructor. However, if the entity class defines any other constructors with arguments, the default no-argument constructor is not automatically generated, and it must be explicitly defined if needed. Therefore, it's a good practice to always include a no-argument constructor in entity classes used with Hibernate to ensure compatibility and avoid potential issues.

#java8