What is a POJO?

• POJO stands for Plain Old Java Object. It is a term used to describe a simple Java class that follows basic coding conventions and does not depend on any specific frameworks or external libraries.

• In simple words, a POJO is just a normal Java object created to hold and manage data in a clean and straightforward way.

Key Features of a POJO

A typical POJO usually includes:

• Private variables (fields) to store data
• Public getter and setter methods to access and update those fields
• Optional methods for additional behavior (like toString())

It may also have:

• A no-argument constructor
• A parameterized constructor

Properties of a POJO
A class is considered a POJO if it does not:

• Extend any predefined class (e.g., HttpServlet, EntityBean, etc.)
• Implement any predefined interface (e.g., javax.ejb.EntityBean)
• Contain framework-specific annotations (e.g., @entity, @Component)

Example

public class Employee {

    private int id;
    private String name;

    // Default constructor
    public Employee() {}

    // Parameterized constructor
    public Employee(int id, String name) {
        this.id = id;
        this.name = name;
    }

    // Getter
    public int getId() {
        return id;
    }

    // Setter
    public void setId(int id) {
        this.id = id;
    }

    // Getter
    public String getName() {
        return name;
    }

    // Setter
    public void setName(String name) {
        this.name = name;
    }
}

What is a JavaBean?

A JavaBean is a special type of POJO that follows a set of strict rules (conventions). It is mainly used to encapsulate data and make it reusable across applications.

Every JavaBean is a POJO, but not every POJO is a JavaBean.

Rules for a JavaBean

• Must implement the Serializable interface.
• Must have a no-argument constructor.
• All fields must be private.
• Each property should have corresponding getter and setter methods.
• Fields must be accessed only through these methods (not directly).

This design provides encapsulation and controlled access to object properties.