gistfile1.txt

data:
    
    interface UserEntity {
      
    }
    
    interface UserDAO {
        public UserEntity getUser(int id);
    }

    class MysqlUserDAO implements UserDAO {
       
       public UserEntityImpl getUser(int id);
       
        private inner class UserEntityImpl implements UserEntity {
    
        }
    }

logic:
    
    
    interface User extends UserEntity {
      
    }
    
    class UserFacade {
        UserDAO dao = new MysqlUser...
        User getUser() {
            return dao.getUser();
        }
    }