Why we make Entity Class final?

In Hibernate, an entity class represents a table in a database, and instances of this class represent rows in that table. Making an entity class final can cause issues for the following reasons:

1.  Proxying

Hibernate uses proxies for lazy loading of entities. A proxy is a subclass that Hibernate generates at runtime to represent the entity. If the entity class is final, Hibernate cannot create a proxy subclass, and lazy loading will not work.

2.  Inheritance Mapping

Hibernate supports inheritance mapping strategies. If an entity class is final, it cannot be extended, and inheritance mapping becomes impossible.

3.  Enhancements and Instrumentation

Hibernate may need to enhance or instrument entity classes for various purposes, such as bytecode manipulation. A final class restricts these enhancements.

Java Example
 Incorrect Example: Final Entity Class 
java
@Entity
public final class Employee {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "name")
    private String name;

    // Getters and Setters
}

In the above example, if we try to use lazy loading or any other feature that requires proxying, Hibernate will throw an exception because it cannot create a proxy for a final class.

Correct Example: Non-Final Entity Class 
java
@Entity
public class Employee {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "name")
    private String name;

    // Getters and Setters
}

In this correct example, the Employee class is not final, allowing Hibernate to create proxies for lazy loading and to use inheritance mapping if needed

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