Introduction to Java information: Simplified data-centric programming in Java

document Particular person(String title, int age) {}

if (obj instanceof Particular person particular person) {
    System.out.println("Title: " + particular person.title());
}

Now let’s contemplate a extra conventional instance. Geometric shapes are a traditional option to display how sealed interfaces work with information, they usually make sample matching particularly clear. The class of this mixture is obvious in swap expressions (launched in Java 17), which allow you to write concise, sort‑secure code that resembles algebraic knowledge varieties in practical languages:

sealed interface Form permits Rectangle, Circle, Triangle {}

document Rectangle(double width, double peak) implements Form {}
document Circle(double radius) implements Form {}
document Triangle(double base, double peak) implements Form {}

public class RecordPatternMatchingExample {
    public static void principal(String[] args) {
        Form form = new Circle(5);

        // Expressive, type-safe sample matching
        double space = swap (form) {
            case Rectangle r -> r.width() * r.peak();
            case Circle c    -> Math.PI * c.radius() * c.radius();
            case Triangle t  -> t.base() * t.peak() / 2;
        };

        System.out.println("Space = " + space);
    }
}

Right here, the Form sort is a sealed interface, allowing solely Rectangle, Circle, and Triangle. As a result of this set is closed, the swap is exhaustive and requires no default department.

Utilizing information as knowledge switch objects

Information excel as knowledge switch objects (DTOs) in fashionable API designs akin to REST, GraphQL, gRPC, or inter‑service communication. Their concise syntax and constructed‑in equality make information best for mapping between service layers. Right here’s an instance: