package headfirst.combining.ducks;public class DuckSimulator {	public static void main(String[] args) {		DuckSimulator simulator = new DuckSimulator();		simulator.simulate();	}  	void simulate() {		Quackable mallardDuck = new MallardDuck();		Quackable redheadDuck = new RedheadDuck();		Quackable duckCall = new DuckCall();		Quackable rubberDuck = new RubberDuck(); 		System.out.println("\nDuck Simulator"); 		simulate(mallardDuck);		simulate(redheadDuck);		simulate(duckCall);		simulate(rubberDuck);	}   	void simulate(Quackable duck) {		duck.quack();	}}