141010 ● class

Process-oriented

Object-oriented

 

Object: all objects. One person, one book, one pen ...... Is an object.

Class is the encapsulation body that includes both data and a group of operations acting on data. It is a model abstracted from a certain object that has something in common.

Object → (abstract) → class

Class → (Instance) → object

Classes generally include: variables (member variables), functions (member functions, member methods)

Class features: encapsulation, inheritance, polymorphism, and abstraction.

Encapsulation:

1. Variables of different classes belong to their own objects

2. The member variables of different objects only belong to their own objects.

3. the variables in the object must be operated through their respective functions, which is safer.

Inheritance:

Subclass can inherit the member variables and member methods of the parent class from the parent class.

Polymorphism:

The morphological diversity of a certain type of objects during execution. This phenomenon becomes polymorphism.

 

1. Declaration class

Class Declaration

{

Member variable Declaration;

Declaration and implementation of member methods;

}

[Modifier (for example: Public)] class <generic> [: parent class] [: interface list]

2. Declare member variables and member Methods

[Modifier] Return Value Type method ([parameter list])

{

Statement sequence;

[Return [return value];

}

3. Member method Overloading

Object Declaration

Class Object

Create an instance

Object = new class Constructor ([parameter list])

Reference object member variables and call object Methods

Object. member variable

Object. Member method ([parameter list])

 

Constructor: Special member functions. If no constructor is written, the system automatically generates a default constructor.

1. Special writing

No return value. The function name can only be the same as the class name.

2. Execute special

Class is automatically executed during instantiation. Constructor is the earliest member function to be executed. Constructor is a function used to generate objects.

Main function: Initialize an object when it is instantiated and generated.

 

1. Declare and call the constructor

Public class mydate

{

Public mydate (INT y, int M, int d) // declare the constructor

{// The constructor has the same name as the class. The constructor returns an instance of the class.

Year = y;

Month = m;

Day = D;

}

}

Mydate d = new mydate (2009, 7, 18 );

2. default constructor

Public mydate ()

 

Overload: functions with the same name and different parameters (number and type) form overload.

The overload is only related to the function name and form parameter, and has nothing to do with the return value.

 

This

Indicates the object itself.

Access member variables and member methods of this class

This. member variable

This. Member method ([parameter list])

This calls other constructors of the current object. Public bird (string name, string color): This (name)

 

Is

Object is class;

True is returned if it is true. Otherwise, false is returned.

 

 

141010 ● class