Design Patterns : Strategy Pattern

AbstractDuck.java

public abstract class Duck {

    FlyBehavior flyBehavior;
    QuackBehavior quackBehavior;

    public void performQuack() {
        quackBehavior.quack();
    }

    public void performFly() {
        flyBehavior.fly();
    }
  
    public void swim() {
        System.out.println("swim");
    }

    public abstract void display();
  
    public void setFlyBehavior(FlyBehavior flyBehavior) {
        this.flyBehavior = flyBehavior;
    }
    
    public void setQuackBehavior(QuackBehavior quackBehavior) {
        this.quackBehavior = quackBehavior;
    }
}

Duck.java

public class Duck {

    FlyBehavior flyBehavior;
    QuackBehavior quackBehavior;

    public void performQuack() {
        quackBehavior.quack();
    }

    public void swim() {
        System.out.println("swim");
    }

    public void performFly() {
        flyBehavior.fly();
    }

    public void display() {
        System.out.println("display");
    }
}

MallardDuck.java

public class MallardDuck extends Duck {

    public MallardDuck() {
        quackBehavior = new Quack();
        flyBehavior = new FlyWithWings();
    }

    @Override
    public void display() {
        System.out.println("mallard duck");
    }
}