Factory Method Pattern(클릭) 
대충은 알아 먹겠는데 해석 하기는 어려운 .. OTL

Singleton Pattern(클릭)

public class Singleton { 

private static final Singleton INSTANCE = new Singleton(); 

// Private constructor prevents instantiation from other classes 

private Singleton() {} 

public static Singleton getInstance() { 

return INSTANCE; } 

}

일반 적인 방법
 
public class Singleton {
   // Private constructor prevents instantiation from other classes
   private Singleton() {}
 
   /**
    * SingletonHolder is loaded on the first execution of Singleton.getInstance() 
    * or the first access to SingletonHolder.INSTANCE, not before.
    */
   private static class SingletonHolder { 
     private static final Singleton INSTANCE = new Singleton();
   }
 
   public static Singleton getInstance() {
     return SingletonHolder.INSTANCE;
   }
 }
Lazy loading 스타일.