blocks|key|660364|text|这是一个很大的问题，答案可以填满多本书，但简而言之，类成员有访问修饰符(public、private、protected)。私有成员可以由其他类成员访问，但不能从外部函数访问。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|660365|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

That's a big question with an answer that fills multiple books, but in short, class members have access modifiers (public, private, protected). Private members can be accessed by other class members, such as a method, but not from external functions.

blocks|key|660403|text|OOP使封装成为可能；因此，状态和行为被封装在表示对象的类中。根据封装发生的级别，使用基于静态(类级别)或实例(对象级别)的封装。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|660404|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

OOP evangelizes encapsulation; as a result, state and behavior is encapsulated in the class representing the object. Depending on what level you the encapsulation to happen, employ either static (class level) or instance (object level) based encapsulation.

blocks|key|660532|text|方法(对象)是一种处理数据结构的范例。数据结构是关于对语义上一致和相关的信息字段进行分组(即结构Person+{FirstName，LastName，DateOfBirth})。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|660533|面向对象编程比数据结构高出一步。在OOP中，我们不仅对相关的数据字段进行分组，而且还包括与数据相关的函数(方法、成员函数)(并以正确的方式对数据进行操作)。|660534|封装是关于保持部分成员对对象是私有的。目标是对外部世界“隐藏”内部工作，并保护对象的状态不被“破坏”，或被赋予不正确的值。OOP语言提供了几个“访问修饰符”，用于指定给定成员是否可以由特定类别的对象(子类的实例、同一“包/名称空间/库”中的类、任何其他类等)访问。|660535|object.method()通常用于请求对象执行某些操作，这些操作可能涉及访问在类外部不可访问的字段。|660536|上面定义并解释了成员函数(方法)的概念和封装的概念是如何并行不悖的。|660537|Referrences:
http://en.wikipedia.org/wiki/Encapsulation_%2528object-oriented_programming%2529
http://en.wikipedia.org/wiki/Object-oriented_programming|code-block|syntax|javascript|660538|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|S|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|T|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|U|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|V|8|@]|9|@]|A|$M|N]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

method(Object) is a paradigm that works with data structures. Data Structures are about grouping fields of information that are semantically consistent and related (i.e. struct Person {FirstName, LastName, DateOfBirth}).

Object oriented programing is one step above data structures. In OOP, we not only group data fields that are related, but we also include functions (methods, member functions) that are related to the data (and that act on the data the correct way).

Encapsulation is about keeping part of the members private to objects. The goal is to "hide" the inner-working from the external world, and protect the object's state from "corruption", or from being assigned incorrect values. OOP languages provide several "access modifiers" that are used to specify whether a given member can be accessed by a specific category of objects (instances of child classes, classes in the same "package/namespace/library", any other class, etc.).

object.method() is usually about asking an object to perform something that may involve accessing a field that is not accessible outside of the class.

The above was to define, and explain how the concept of member function (method), and the concept of encapsulation go hand in hand.

<pre><code>Referrences:
http://en.wikipedia.org/wiki/Encapsulation_%28object-oriented_programming%29
http://en.wikipedia.org/wiki/Object-oriented_programming
</code></pre>

blocks|key|660642|text|另一个需要牢记的答案。当您执行方法(对象)时，方法是这样实现的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|660643|method(obj)
{
++++return+obj.getA()%2Bobj.getB()
}|code-block|syntax|javascript|660644|这很糟糕，因为以后当你想再次做同样的事情时，你的代码在哪里？我的意思是，它使用A和B，所以你首先要去看的地方是obj，但它不在那里！？！现在你得去找了。|660645|OO与组织代码以查找和重用代码一样重要。|660646|tl;dr+rant|660647|您可以在bean模式中看到许多类似的代码--正因为如此，我将bean看作是OO编程中最隐秘的邪恶之一。理论上，现在的大多数bean被称为"Pojos“，因为你可以在其中实现实际的方法，但人们仍然坚持使用充满setter和getter的bean，这绝不是面向对象的，事实上，他们鼓励编写专门不是面向对象的代码(bean更类似于非面向对象语言中的数据结构，比如C语言，而不是任何面向对象的语言)。|660648|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

One other answer to keep in mind. When you do method(object) and method is implemented like this:

<pre><code>method(obj)
{
 return obj.getA()+obj.getB()
}
</code></pre>

This is bad because later when you want to do the same thing again, where is your code? I mean, it uses A and B, so the first place you'd go to look is obj, but it's not there!?! Now you have to go search.

OO is as much about organizing code to find and reuse it as anything else.

tl;dr rant

You see a LOT of code like this with the bean pattern--I've come to see beans as one of the more insidious evils in OO programming because of this. In theory most beans these days are called "Pojos" because you CAN implement actual methods in them, but people still stick with beans full of nothing but setters and getters which is in no way OO, in fact they encourage code that is specifically NOT OO (beans are more akin to data structures in a non-oo language like C than anything OO has).

I am struggling to explain oop concepts in java.

A major tenet in oop is that objects have methods; so Object.method(); works.
I am contrasting this with procedural programming in which one must do method(Object).

Is this called encapsulation?

What are the advantages of the oop way?

Java OOP encapsulation. Why is Object.doSomething(); better than doSomething(Object);?

数据结构

我正在努力解释java中的oop概念。oop中的一个主要原则是对象有方法；所以Object.method()；有效。我将这与过程性编程进行了对比，在过程性编程中，人们必须做方法(对象)。这是所谓的封装吗？oop方式的优点是什么？

问Java OOP封装。为什么Object.doSomething()；比doSomething(Object)；好？
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