[筆記]一些OOP最基本的概念

Object:
*. 一個object最重要的兩個characteristics—state, behavior。(Real-World中的物件也是一樣的概念)

*. State相當於一個物件所有的特徵。例如長度，高度，名稱，種類，顏色等等。

*. Behavior相當於這個物件能做的行為。例如跑，跳，說話，搖尾巴等等。

*. An object stores its state in fields (variables in some programming languages) and exposes its behavior through methods (functions in some programming languages).

*. Hiding internal state and requiring all interaction to be performed through an object's methods is known as data encapsulation

Class:
*. Class相當於做出一個Object的藍圖或是模型，不是instance本身。

Inheritance:
*. Common behavior can be defined in a superclass and inherited into a subclass using the extends keyword.

Interface:
*. Methods的集合，無implementation。
*. API: Application Programming Interface.

Package:
*. 用途相似的類別分門別類放在folder裡面。