Java-Grundlagen

package at.aydin.lab.basics.legacy;

// Design Pattern: JavaBean
// Zweck: Historische mutable Datenstruktur mit leerem Konstruktor und Settern.
public class LegacyCustomer {
    private long id;
    private String name;
    private String status;
    public LegacyCustomer() {
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public String displayText() {
        return id + ": " + name + " [" + status + "]";
    }
}

package at.aydin.lab.basics.modern;

// Design Pattern: Value Object
// Zweck: Unveränderliche, validierte fachliche Daten mit wertbasierter Gleichheit.
public record Customer(long id, String name, CustomerStatus status) {
    public Customer {
        if (id <= 0) throw new IllegalArgumentException("id muss positiv sein");
        if (name == null || name.isBlank()) throw new IllegalArgumentException("name fehlt");
        if (status == null) throw new IllegalArgumentException("status fehlt");
    }

    public String displayText() {
        return "%d: %s [%s]".formatted(id, name, status);
    }
}

package at.aydin.lab.basics.modern;

public enum CustomerStatus {
    ACTIVE, INACTIVE
}

package at.aydin.lab.basics.legacy;

public final class BasicsLegacyApplication {
    private BasicsLegacyApplication() {
    }

    public static void main(String[] args) {
        LegacyCustomer customer = new LegacyCustomer();
        customer.setId(42L);
        customer.setName("Aydin");
        customer.setStatus("ACTIVE");
        System.out.println(customer.displayText());
    }
}

package at.aydin.lab.basics.modern;

public final class BasicsModernApplication {
    private BasicsModernApplication() {
    }

    public static void main(String[] args) {
        System.out.println(new Customer(42, "Aydin", CustomerStatus.ACTIVE).displayText());
    }
}