What is the difference between Java class and Java record?

Mia 53 Published: 12/08/2024

What is the difference between Java class and Java record?

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Java records are a new concept introduced in Java 14 (released in March 2019) as part of Project Amber, which aims to standardize language enhancements. A Java record is a small, simple class that allows for concise definition and use. Records can be seen as a simplification of classes, focusing on immutability, serialization, and hashcode generation.

The main differences between a Java class and a Java record are:

Immutability: Records in Java are immutable by default, meaning once created, their state cannot be changed. This makes them suitable for creating simple data carriers that represent business entities or domain models. In contrast, classes can have mutable fields and methods that modify the object's state. Serialization: Java records automatically implement the Serializable interface, making it easy to serialize them into JSON or XML formats. Records also provide a default no-arg constructor, so they can be easily deserialized from a stream of data. Classes can implement serialization as well, but it requires more manual effort and boilerplate code. Hashcode generation: Java records automatically generate their own hashcode when implementing the equals() method. This allows for proper equality checking between record instances. Classes require more manual effort to implement an effective hashcode generator. Builder pattern: Records often use the builder pattern, which helps in creating immutable objects and provides a convenient way of setting fields using a fluent API. Builders are not unique to records, but they are closely related. Inheritance: Records do not support inheritance; once you create a record class, you cannot inherit from it or create subclasses. Classes can inherit from other classes or interfaces in the traditional sense. Methods and constructors: Records have fewer methods and constructors compared to classes. They typically only need a constructor for initialization and possibly an equals(), hashCode(), and toString() method. Classes, on the other hand, can define their own custom constructors, methods, and fields. Syntax: The syntax for defining records is more concise than that of traditional classes. Records are declared using the record keyword followed by the record's name, and they require fewer boilerplate code.

In summary, Java records are a new way to create small, simple data carriers in Java that provide immutability, serialization, and hashcode generation out of the box. While classes can also achieve these features with more manual effort, records offer a simplified, concise way to define and use immutable objects.

When to use Java Records

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Java Records are a relatively new feature introduced in Java 14 (released in 2019). They were designed to simplify the process of creating immutable data carrier classes, which are often used as transfer objects or value objects.

Before Java Records, you might have created such classes by using a combination of constructors, getters, and setters. Here's an example of how you might define a Person class without records:

public final class Person {

private String name;


private int age;


public Person(String name, int age) {


this.name = name;


this.age = age;


}


public String getName() {


return name;


}


public int getAge() {


return age;


}


}

To create a new Person object, you would need to write code that calls the constructor and sets the properties:

Person person = new Person("John", 30);

String name = person.getName();


int age = person.getAge();

Java Records simplify this process by allowing you to define a class with just two parts: the record declaration and the constructor. Here's how you might redefine the Person class using a Java Record:

public record Person(String name, int age) {

}

The record declaration specifies that the class is a record, and the constructor takes two parameters: name and age. You can then create a new Person object like this:

Person person = new Person("John", 30);

String name = person.name();


int age = person.age();

Java Records have several benefits. They simplify your code by reducing the amount of boilerplate code you need to write. They also provide better encapsulation, as you can't access the record's fields directly; you must use the getter methods.

In summary, Java Records are a new feature in Java that simplifies the process of creating immutable data carrier classes. They allow you to define such classes with just two parts: the record declaration and the constructor. This reduces the amount of boilerplate code you need to write and provides better encapsulation.

Java Records can be used in various situations, such as:

Transfer objects: Java Records are well-suited for creating transfer objects that hold data and are passed between systems or layers. Value objects: They can also be used to create value objects that have inherent value but don't necessarily change over time. Data carriers: Records can serve as a simple way to encapsulate data in your application.

Java Records are particularly useful when:

You need to simplify code: If you find yourself writing repetitive, boilerplate code for immutable data classes, Java Records can help simplify the process. You want better encapsulation: Records provide better encapsulation than traditional immutable classes because they prevent direct access to the fields. You're working on a project that requires transfer objects or value objects: In this case, Java Records can help you create these types of objects more efficiently.

In conclusion, Java Records are an exciting new feature in Java that simplifies the process of creating immutable data carrier classes. They provide better encapsulation and reduce boilerplate code, making them a valuable tool in your Java programming toolkit.

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