public class Singleton { private static Singleton instance; private Singleton() {} public static Singleton getInstance() { if (instance == null) { instance = new Singleton(); } return instance; } } Next, they encountered the Factory, a versatile pattern that allowed them to create objects without specifying the exact class. The Code Crusaders saw how this pattern enabled them to write more flexible and maintainable code.
public interface Observer { void update(String message); } dive into design patterns pdf github top
public interface Turkey { void gobble(); } public class Singleton { private static Singleton instance;
public class TurkeyAdapter implements Duck { private Turkey turkey; public TurkeyAdapter(Turkey turkey) { this.turkey = turkey; } @Override public void quack() { turkey.gobble(); } } Their travels next took them to the domain. Here, they encountered the Observer, a pattern that allowed objects to notify others of changes without creating tight couplings. The Code Crusaders saw how this pattern facilitated loose coupling and improved extensibility. Here, they encountered the Observer, a pattern that
public class Dog extends Animal { @Override public void sound() { System.out.println("Woof!"); } }
(PDF and GitHub links can be found in the references below)
public interface Subject { void registerObserver(Observer observer); void notifyObservers(); }