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

document Individual(String identify, int age) {}

if (obj instanceof Individual particular person) {
    System.out.println("Identify: " + particular person.identify());
}

Now let’s take into account a extra conventional instance. Geometric shapes are a basic technique to show how sealed interfaces work with data, and so they 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 sorts in useful 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 essential(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 data as knowledge switch objects

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