Паттерн Мост (Bridge). Пример кода

public abstract class Animal {
    AnimalImp animalImp;
    public Animal(AnimalImp animalImp) {
        this.animalImp = animalImp;
    }
    public void say() {
        animalImp.say();
    }
}

public class HappyAnimal extends Animal {
    public HappyAnimal(AnimalImp animalImp) {
        super(animalImp);
    }
}

public interface AnimalImp {
    public void say();
}

public class Cat implements AnimalImp {
    public void say() {
        System.out.println("Miaou! I'm a happy cat!");
    }    
}

public class Pig implements AnimalImp {
    public void say() {
        System.out.println("Groin-groin! I'm a happy pig!");
    }    
}

public class Rooster implements AnimalImp {
    public void say() {
        System.out.println("Cocorico! I'm a happy rooster!");
    }    
}

import java.util.ArrayList;
import java.util.List;

public class Client {
    public static void main(String[] args) {
        List happyAnimals = new ArrayList();
        happyAnimals.add(new HappyAnimal(new Cat()));
        happyAnimals.add(new HappyAnimal(new Pig()));
        happyAnimals.add(new HappyAnimal(new Rooster()));
        
        for (Animal animal: happyAnimals) {
            animal.say();
        }
    }
}
/**
 * Output:
 * Miaou! I'm a happy cat!
 * Groin-groin! I'm a happy pig!
 * Cocorico! I'm a happy rooster!
 */