Object-oriented concepts, class-to-object relationships

Basic object-oriented concepts:
1. What is Object-oriented
1, object-oriented is a kind of programming idea
2, object-oriented is a thinking way of thinking problem
2, the establishment of object-oriented thinking mode
1, first whole, then local
2, first abstract, in concrete
3, what can do, and how to do
3. How to learn object-oriented
1. Mastering an object-oriented language grammar
2, familiar with object-oriented design principles
3, familiar with object-oriented design patterns

Overview of Facing objects:
1. Three characteristics of the object (recognized): encapsulation, inheritance, polymorphism. (It can be said that the four characteristics: encapsulation, inheritance, polymorphism, abstraction)
2. In the development of the first object, do not set up an object, the actual object is to find objects, establish objects and maintain the relationship between objects.

The relationship of a class to an object:

What is a class
1, class is: classification, category
2, through the classification, we can distinguish different kinds of things, in daily life, we often do this
3, therefore, a class is a set of things that have the same attributes (attributes) and behaviors (methods)

A class is a template for an object that is an individual instance of a class
1. The class is the description of things in real life------mapped to Java, the description is class defined classes (classes are abstract, conceptual, representing a class of things, such as human, cat)
2. Object is the entity that these things exist-------concrete object is the corresponding Java in the heap memory with the new entity (object is concrete actual representative of a specific thing)

How to define a class:
1. In fact, defining a class is describing things as defining properties and behaviors, and attributes and behaviors become members of the class (member variables and member functions)
2. The attribute corresponds to a variable in the class, and the behavior corresponds to the method in the class

The definition format of the class
In Java, you can use the following statement to define a class
Class Name {
property name;
Return value type method name () {}
}

Requirements: Describe the car (color, number of tires). Describing things is describing the properties and behavior of things.

1 classcar{2     //The attribute that defines a thing corresponds to a member variable in a class3String color= "Red";4     intNum=4;5     //The definition behavior corresponds to a member function (method) in a class6     voidrun () {7System.out.println (color+ "...." +num);8     }9 Ten      One     /* A Public static void Mian (string[] args) { - car c = new car ();//You can create this class object in this class so that the car class can run independently -     } the     */ - } -  -  +  Public classObjectdemo { -      Public Static voidMain (string[] args) { +Car c=NewCar ();//production cars generate an entity in heap memory with the new keyword, and C is the reference variable of the class type that points to the object of that class A  at         //Command object to do things object name. Object Member -C.color= "Blue"; - C.run (); -     } -}

Object-oriented concepts, class-to-object relationships