Abstract: This paper uses the philosophical thinking through the process of recognition of the objective world and a detailed description of methods, easy to understand introduction to the concepts of object-oriented and related concepts.
Keywords: object-oriented class objects
Philosophical view is that the real world is the variety of entities (things, objects) are formed, each object has its own in the internal state and movement law between different objects interconnected and Xianghuzuoyong constitute Gezhong different systems, and thus constitute the objective world. Meanwhile people in order to better understand the objective world, to have similar laws within the state and the movement of entities (things, objects) integrated together as class. Class is similar laws within the state and the movement of abstract entities, then it is the abstract that the objective world of things by different classes of mutual contact and interaction between the composition of a whole. Computer software is to simulate the real world, so that the various real-world system can be realized in the computer, and then for us to work, study and live help.
Figure 1, the objective world and subjective world
1, object-oriented (object-oriented; short: OO) has no unified concept, and I here it is defined as: awareness of the objective world by the system way of thinking, based on the object (entity) the concept of modeling, simulation the objective world, analysis, design, implementation, software solution. Through the concept of object-oriented software system with the computer in the system correspond to the real world.
2, object (object): i.e. the real world in a variety of entities. It can refer to specific things you can refer to abstract things. Such as: integer 1,2,3, rogue Chen Shui-bian, Apple, aircraft, rules, laws, regulations, forms and so on. Each object has its own internal state and sports law, such as rogue Chen Shui-bian has the name, height, weight and other internal state, has to eat, sleep, assault, tax evasion and other sports law. In object-oriented concept, we called the internal state of an object property, sports law as a method or event.
3, type (class): Class is a similar movement within the state and the law of the set of entities (or collectively, abstract). The concept of class comes from the awareness of nature and society in the process. In this way, people mainly use two methods: from specific to general induction and deduction from the general to the specific method. In the induction process, we were specific things from a common feature in the extracted form a general concept, which is "classified"; such as: insects, lions, reptiles, because they can move so classified as animal. In the interpretation of this kind of thing that we again, according to different characteristics into different categories, this is the "Category"; like animal -> Cats -> Cat -> Tabby Cat and so on. For a specific class, it has many specific individuals, we have control of these individuals are called "objects." Class is the class of the internal state of the common state of objects in the collection; class law of motion is a common class of objects in a collection of sports law. Such as: Deborah diagram of making the following definition: people are not able to walk upright animal hair. Defined in Bora map of "man" is a class with "no hair stood upright," and some other common characteristics different from other things; and Joe Smith, John Doe, Wang V, Chen Shui-bian and so a rogue a specific person, "people" of this class one by one "object."
4, message (Message): message is the interaction between objects and interact. A message from the five major components: the object of sending messages, receiving messages of objects, message passing approach, the message content (parameters), feedback.
Figure 2 message mechanism
5, class characteristics: the definition of the class determines the class has the following five characteristics: abstraction, inheritance, encapsulation, overloading, polymorphism.
1) abstract: a clear definition of the class that class is a group of law within the state and the movement of abstract objects, abstract from the general point of view is a way of looking at things, it requires that we focus on the essential characteristics of things (internal state and sports law), rather than specific details of the implementation. Abstract object-oriented point of view encourages us to look at the real world, that is, the real world is a set of abstract objects - class composition.
2) Inheritance: Inheritance is the class of the relationship between different levels of abstraction. Class definitions are mainly two kinds of methods of induction and deduction; summarized by a number of special classes of general category known as the parent of these special classes, special classes as a subclass of the general category, the same parent can be deduced subclass; parent class is a subclass higher level abstraction. Subclass can inherit the parent class of all internal laws of the state and movement. The use of computer software development in succession, providing a kind of normative hierarchy; through class inheritance, so that the characteristics of the public to share and improve software reusability.
3) Package: links between objects and interacting with each other primarily through the message system can be achieved. Objects do not need to know any more about each other's internal law of a specific state or movement. Object-oriented class is a good package, module, class definition to explain (the user can see the external interface) and implementation (users do not see the internal implementation) explicitly separate the specific definition of its internal realization of the scope of its protection . Class is the basic unit of encapsulation. Package to prevent the process of change brought about interdependence effects. Defined in the class to receive the other message is called an interface class.
4) Polymorphism (cover): Polymorphism refers to the method of the same name in different classes with different law of motion. Deduction for the child in the parent class, class, sport can also interpret the law, interpretation of the same name to subclass the form of sports or exercise more specific rules, or even sub-class can have different parent form law of motion or movement. Different sub-classes can be interpreted a different law of motion. If animals are eating, and sheep and wolves do not eat the same manner and content, figure 3.
Figure 3: Polymorphism of class methods
5) Heavy: Heavy class with the same name refers to its passing in different parameters that can have a different law of motion. The interaction between the object, even if the received message object used to receive the same way, but the level of detail different message, receive message object movement within the law may be different. Figure 4, the boss assign buyers to buy things, when the boss did not specify what to buy, the buyer might default to buy sweet potatoes; as specified in the boss to buy rice to buyers, buyers may be to the nearest supermarket to buy 10 kilograms of rice; as specified boss Buyer tonight to buy five kilograms of rice Dongjiekou Fuzhou, according to the boss that buyers will have to specify the time and place to buy 5 kilograms of rice.
Figure 4: Method overloading
6, including: philosophy that real world connections between different objects and interaction constitute a variety of different systems, the linkages between different systems and interaction constitute a more complex system, which in turn constitute the world. Concept in object-oriented system as these packages.
7, including the interface classes: interaction of the system hidden within the system when the Wei Liao concrete realization of the system interface to interface, through the establishment of a class or object to interact with other systems; to other systems only to see that it is this interface, the interface class or object, This class is called object-oriented interface classes.
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