OO 디자인 모드 소결

< head first design pattern > 및 위 키 참조
OO : Abstraction; Encapsulation; Polymorphism; Inheritance
OO principle:
    * 다양한 것 을 캡슐 화 합 니 다. (기본 규칙, 전략 패턴) 패 키 징 변화;
    * Favor composition over inheritance. 조합 을 많이 사용 하고 계승 을 적 게 사용 합 니 다.
    * Program to interfaces, not implementations. 인터페이스 프로 그래 밍 에 대해 프로 그래 밍 을 실현 하지 않 습 니 다.
    * Strive for loosely coupled designs between objects that interact. 상호작용 대상 간 의 느슨 한 결합 디자인 을 위해 노력 합 니 다.
    * classes should be open for extension but closed for modification. 클래스 는 확장 에 대해 개방 하고 수정 에 대해 닫 아야 합 니 다.
    * 추상 화 에 따라 달라 집 니 다. 콘크리트 클래스 에 의존 하지 마 십시오. (의존성 Inversion Principle) 추상 화 에 의존 하고 구체 적 인 클래스 에 의존 하지 마 십시오.
    * Only talk to your friends. (Principle of Least Knowledge) 친구 와 만 대화 하기;
    * 우 리 를 부 르 지 마 세 요. 우 리 는 당신 을 부 를 겁 니 다. (The Hollywood Principle, High - level components control when and how low - level components can participation in the computation. 하지만 high - level components directly 라 고 부 르 지 마 세 요.) 찾 지 마 세 요. 찾 을 거 예요.
    * A class should have only one reason to change. (Single Responsibility Principle) 클래스 는 변 경 된 이유 가 하나 밖 에 없어 야 합 니 다.
Creational patterns:
Abstract factory : Provide an interface for creating families of related or dependent objects without specifying their concrete classes.
Factory method : Define an interface for creating an object, but let subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.
Builder : Separate the construction of a complex object from its representation so that the same construction process can create different representations.
Prototype: Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype.
Singleton : Ensure a class has only one instance, and provide a global point of access to it.
Structural patterns:
Adapter : Convert the interface of a class into another interface clients expect. Adapter lets classes work together that couldn't otherwise because of incompatible interfaces
Bridge : Decouple an abstraction from its implementation so that the two can vary independently.
Composite : Compose objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.
Decorator: Attach additional responsibilities to an object dynamically keeping the same interface. Decorators provide a flexible alternative to subclassing for extending functionality.
Facade : Provide a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface that makes the subsystem easier to use.
Flyweight: Use sharing to support large numbers of fine-grained objects efficiently.
Proxy : Provide a surrogate or placeholder for another object to control access to it.
Behavioral patterns
Chain of responsibility : Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it.
Command : Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations.
Interpreter: Given a language, define a representation for its grammar along with an interpreter that uses the representation to interpret sentences in the language.
Iterator : Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation.
Mediator : Define an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently.
Memento : Without violating encapsulation, capture and externalize an object's internal state so that the object can be restored to this state later.
Observer : Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.
State : Allow an object to alter its behavior when its internal state changes. The object will appear to change its class.
Strategy : Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from clients that use it.
Template method : Define the skeleton of an algorithm in an operation, deferring some steps to subclasses. Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure.
Visitor : Represent an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operates.

/** 
  * State 
  */
public class GumballMachine {
    State souldOutStates;
    State noQuarterStates;
    State hasQuarterStates;
    State souldStates;
    State winnerStates;

    State state=souldOutState;
    int count=0;
  
    ...
}

/** Flyweight Pattern
  *   ：          ，                。    
  *   ：            ，    ；   “  ”         ；
  *   ：                    
  * /
//in pattern
public class TreeManager{
    ArrayList treeArray;

    displayTrees(){
    //          
         display(x,y,age);
    }
}

class Tree{       //             
    display(x,y,age){}
}

//withoutPattern
public class Tree{
    int xCoord;
    int yCoord;
    int age;
    
    display(){}
}