Buat class lingkaran
public class lingkaran {

    private double radius;

    public lingkaran(double radius) {
        this.radius = radius;
    }

    public void Luas() {
        double luas = 3.14 * radius * radius;
        System.out.println("Luas lingkaran " + luas);
    }
}

Buat class Main
public class Main {

    public static void main(String[] args) {
        Anjing object = new Anjing();
        object.tampilSuara();
        object.suaraAnjing();
        System.out.println("");

        Kucing object2 = new Kucing();
        object2.tampilSuara();
        object2.suaraKucing();
    }
}