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.