What is UML
The full name of UML is Unified Modeling Language, also known as Unified Modeling Language. A standard language for specifying, visualizing, and documenting products for object-oriented development systems.
Features of UML
.UML unifies different approaches to different types of systems, different development stages, and different internal concepts, thereby effectively eliminating unnecessary differences between various modeling languages. It is actually a general-purpose modeling language that can be widely used by users of many object-oriented modeling methods
.UML modeling capabilities are stronger than other object-oriented modeling methods. It is not only suitable for the development of general systems, but also especially suitable for the modeling of parallel and distributed systems
.UML is a modeling language, not a development process
object-oriented approach
Object-oriented (Object Oriented, referred to as OO) method regards the world as independent objects, and there is no causal relationship between them. Only when driven by an external force, can objects transfer information to each other with a certain law. These interactions constitute a "process" of this living world. In the absence of external force, the object remains in a "still" state.
From a microscopic point of view, these independent objects have a wonderful set of properties. For example, the object has a hard shell. From the outside, except for the message channel it uses to interact with the outside world, the inside of the object is a black box, and nothing can be seen, which is called encapsulation; for example, objects can be combined together. A new object is formed, and the combined object has the sum of the characteristics of the first two, which is called aggregation; the object can be bred, and the child born will have all the abilities of the parent, which is called inheritance; the object is multi-faceted, he will One of the faces is displayed according to different requirements, which is the interface; multiple objects may have the same face, but behind this face has different behaviors, which is polymorphism...
From a macro perspective, objects are "short-sighted" "Yeah, he doesn't know what's going on in the whole world it's in, or how its actions contribute to the world. It only knows a group of friends around it that it has contact with (this is called dependence), and maintains a relationship of information exchange (this is called coupling) with the small partners. Colleague objects are also "selfish", even among partners, each object still stubbornly protects his territory, only allowing others to communicate through the small window she opens (this is called a method), never Open up to the other person.
The fundamental difference between object-oriented and process-oriented methods is that the world is not regarded as a closely connected system, but as some independent small parts, which are organized according to certain rules to complete a specific function. It turns out that the process is not the origin of the world, and the process is "expressed" by some objects organized by specific rules. This difference between object-oriented and process-oriented led to a revolution in the analysis and design method. Analysis and design change from process analysis to object acquisition, and from data structure to object structure.
But everything is not perfect, there will always be some difficulties:
. How are objects abstracted?
.Why abstract objects like this
.如何组合抽象出来的对象正好可以满足需求？
.抽象出来的对象又是如何表达需求的？
说到了这里，就不得不说一下建模了，因为它就是解决上述问题的答案！！！
欲知后事如何，请看下回分解！
