Java Record Types, introduced in Java 14 as a preview feature and made stable in Java 16, provide a concise way to define immutable data carriers. They are designed to simplify the task of creating simple data-holding classes by reducing boilerplate code and ensuring immutability and equality semantics.

What is a Java Record?

A Java Record is a special kind of class in the Java programming language that is used to model immutable data. Records automatically generate constructors, accessors, equals(), hashCode(), and toString() methods, making them ideal for data transfer objects.

Defining a Record

Defining a record in Java is straightforward. Here’s a simple example:

public record Person(String name, int age) {}

In this example, the Person record automatically includes:

• A private final field for each component (name and age).
• A public constructor that initializes these fields.
• Getter methods for each field (name() and age()).
• equals(), hashCode(), and toString() methods.

Benefits of Using Records

1. Conciseness: Records reduce boilerplate code significantly. No need to manually write getters, equals(), hashCode(), and toString() methods.
2. Immutability: Records are inherently immutable, ensuring that their fields cannot be modified after the record is created.
3. Enhanced Readability: Code that uses records is cleaner and easier to understand.

Example Usage of Records

Here is a practical example of how records can be used in a Java application:

public record Employee(int id, String name, double salary) {}

public class RecordExample {
    public static void main(String[] args) {
        Employee emp = new Employee(1, "Alice", 75000);
        System.out.println(emp);

        // Accessing fields
        System.out.println("ID: " + emp.id());
        System.out.println("Name: " + emp.name());
        System.out.println("Salary: " + emp.salary());
    }
}

Output:

Employee[id=1, name=Alice, salary=75000.0]
ID: 1
Name: Alice
Salary: 75000.0

Customizing Records

While records provide a lot of functionality out of the box, you can still customize them if needed. For instance, you can add validation logic in the canonical constructor:

public record Product(String name, double price) {
    public Product {
        if (price <= 0) {
            throw new IllegalArgumentException("Price must be positive");
        }
    }
}

Conclusion

Java Records are a powerful addition to the Java language, making it easier to create immutable data carriers with minimal code. They enhance code readability and reduce boilerplate, allowing developers to focus on the core logic of their applications.