Java is a versatile and widely-used programming language that provides various constructs for data modelling and manipulation. Two common approaches for defining classes to represent data are POJO (Plain Old Java Object) and Record classes. Both have their distinct use cases and benefits, and understanding the differences between them is crucial for writing efficient and maintainable Java code. In this blog, we'll explore the characteristics and contrasts between POJO and Record classes in Java.
1. POJO (Plain Old Java Object): A POJO is a conventional Java class that encapsulates data and provides getter and setter methods for accessing and modifying the data. It adheres to the JavaBean conventions, which require the class to have a default constructor and follow the naming conventions for getter and setter methods. POJOs are commonly used for data transfer objects, entity classes, or model classes in various applications.
Characteristics of POJO:
Private fields: POJO classes typically have private fields to encapsulate data and maintain data integrity by controlling access through getter and setter methods.
No additional behavior: POJOs mainly focus on representing data and do not include any business logic or additional behaviors within the class.
Manually generated boilerplate code: In POJOs, you need to write boilerplate code for constructors, getter and setter methods, equals(), hashCode(), and toString() methods manually.
public class Person {private String name; private int age;public Person() { // Default constructor }// Getter and Setter methods for name and age// equals(), hashCode(), and toString() methods are not shown here. }
2. Record Class: Introduced in Java 14, a record class is a concise and convenient way to create classes primarily meant for data holding. It is a form of data class that automatically generates the required methods like constructors, equals(), hashCode(), and toString() based on the class's state. The primary objective of record classes is to reduce boilerplate code and improve readability by providing a simpler syntax for creating data classes.
Characteristics of Record Class:
Automatic generation of methods: Record classes automatically generate constructors, accessor methods, equals(), hashCode(), and toString() methods based on the fields declared in the class. This feature significantly reduces boilerplate code.
Immutability: Record classes create immutable objects, meaning their fields cannot be modified once the object is created. This property enhances thread safety and prevents accidental data modifications.
Final by default: Fields in record classes are implicitly final, ensuring that their values cannot change after object creation.
Example of a Record Class:
public record Person(String name, int age) { // Record classes don't require explicit constructor, getter, equals(), hashCode(), or toString() methods }
Differences between POJO and Record Classes:
Boilerplate Code:
POJOs require manually written boilerplate code for constructors, getter and setter methods, equals(), hashCode(), and toString() methods.
Record classes automatically generate the above methods based on the class's state, reducing boilerplate code significantly.
Mutability:
POJOs can be mutable or immutable depending on how they are designed.
Record classes are always immutable, ensuring the state of the object remains constant after creation.
Use Cases:
POJOs are used when additional behaviors or complex logic needs to be added to the class, or when immutability is not desired.
Record classes are ideal for simple data-holding classes, where immutability and minimal boilerplate code are preferred.
Java Version:
POJOs are available in all versions of Java.
Record classes were introduced in Java 14 and are available in later versions.
Conclusion:
Both POJO and Record classes are valuable tools for representing data in Java. POJOs provide flexibility for adding additional behavior to the classes, while Record classes offer a concise and elegant way to define immutable data-holding classes with minimal boilerplate code. Depending on the requirements of your application, you can choose the appropriate approach to design your classes and make your Java code more efficient and maintainable.