Introduction to Programming (Java) 1.1.2 Upside Down World (Plato's Law)

The introduction to Programming (Java) Plato the principles of Law, Liskov and Parnas as the three cornerstones of the object-oriented programming paradigm.

The first principle of object-oriented paradigm, yqj2065 called Plato's Law, is the source of conceptual paradigm and psychological paradigm of object technology, and object technology simulates the real world of materialism by reversing the idea world.

★ Plato's Law: The world of the class exists independently, and the object world is created by the class.

Although it was felt that this principle was very natural and there was no need to raise and emphasize it, I found that the principle of degree of understanding and acceptance， determines the degree to which you perceive the object opposite to you.。

The basis for the proposed:

1 . An object is a term with a strong philosophical flavour, intended to refer to one or more (human) senses, in particular to something, object, or thing that can be sensed by sight or touch. The real world is made up of objects/object.

2. People see this yellow dog, the Pug, at this time, the human play its abstract (v. Abstract) ability , from a specific object to extract the category/type concept of ' dog ' or ' dog '. Further evolution is confusing-humans abstract concepts that have no direct physical counterpart. For example, in the geometry of "circle", there is no object in real life can fully satisfy the mathematical completeness of the circle, even if the use of compasses carefully.

3, the problem domain of the software is part of the real world. Plato's theory of philosophy, just right for the software's solution domain: all concepts/types!

Application:

The 2 class precedes the object existence. Classes can exist independently. As a concept,Dog.class can exist statically on a hard disk , and it does not care if there are any active dogs in the world (in memory). The classes in the JDK, shown in 1-3, exist on the hard disk. While the program is running, Dog.class is dynamically present in memory, and then (if necessary) creating objects of this class, referring to [class 7.1 loading].

2 There is a natural presence, a static member of a class . "yqj2065 does not agree with the ACM Java task Force/java Ad Hoc Working group, and does not think that static members are outdated, is a teaching difficulty"

2 start of the program run, publicstatic void Main (String [] args), it is out of nothing. The first object is created from the beginning of the start. An object can create additional objects by executing its methods.
2 as a template, the concept creates its own objects. The basic way to create an object is the "new constructor ()" expression, which is called the class's instance creation expression (class instance createexpression), which calls it a new expression .

paradigm (Paradigm)

Concept Paradigm : The different ways of looking at the world and applying science. This is a set of metaphysical beliefs about the outside world, formed according to unique values and standards. For example, there is no "uncertainty" in Newton's eyes, and microscopic physics describes many uncertainties. The conceptual paradigm of OOP: As is said in [1.1.3 object-oriented],

★ Object-oriented technology simulates the real world of materialism by reversing the world of ideas.

1. The program is a collection of loosely coupled classes.

2. Program execution/process is a complex with many objects, and the objects form an interdependent and interactive society.

3. Programming is not about writing instruction sets, but creating a world of self-managed, interacting objects. "See 0.2.2 Operators and operands"

In the absolute ultimate sense, programming is to write a string of computers will follow the instruction set, however, from the perspective of solving practical problems, according to the machine's thinking is not cute, it is not in line with people's thinking, and not easy for programmers to express their ideas to solve large and complex problems. Therefore, it is useful and interesting for object-oriented technology to look at the procedure in the way of people's understanding rather than the machine, and to organize it in a manner that is more in line with people's thinking, which is the important reason of object technology becoming the mainstream programming technology at present.

Psychological cognitive factors-- Psychological Paradigm。 Under different view of nature and logic, the scientific community has a "pious fanaticism" in its paradigm, and tries to put the nature "forced into" the ideological framework stipulated in the paradigm, so as to carry out fruitful research activities. When the paradigm changes, not only the people who are engaged in scientific research are changed, the criteria of evaluation and selection, the whole social psychology, the research tradition and the world schema are all changed, so the old and new paradigm is not universal and can not be compared.

Object-oriented programmers should be programmed according to the metaphor of everyday life (mental paradigm).

The programming paradigm is perhaps the most important term to be understood when learning any programming language, because teaching a specific language is not the purpose of computer science education, but rather the paradigm behind the language.

It is often said that learning object-oriented is the key to mastering its thoughts. What is "thought"--too Chinese vocabulary, in fact, is the object-oriented programming paradigm.

Although the logical system of discipline-the rule paradigm is important, for example, the object-oriented rule paradigm includes not only the concepts of polymorphism , encapsulation, inheritance and object-oriented design , but also design patterns, object-oriented software engineering, unified Modeling Language, JUnit, etc. (just random examples, Not comprehensive). However, the procedural concept (conceptual paradigm) and the mental paradigm of programming are also very important, requiring textbooks or teachers to pass on or instill in students repeatedly and imperceptibly . Simple teaching grammar is the worst way to teach. This is one reason I emphasize Plato's law. So, to list this principle, not to install B, but I think it is really important.

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Introduction to Programming (Java) 1.1.2 Upside Down World (Plato's Law)