C # inheritance and polymorphism,

C # inheritance and polymorphism,

Inheritance: in A program, if A Class A: Class B, this mechanism is inheritance.

Can subclass inherit all content (members) of the parent class?

Resolution:

1. Private Members (attributes and methods)

2. Constructor

3. The final-modified method. The subclass cannot be rewritten.

// SE is a subclass of PM

// SE inherits PM

class SE:PM    {        public int n;        public SE(int i,int n,int m){                        }    }

　　

class PM    {        public int money { get; set; }        public int gaga { get; set; }        public PM(int money, int gaga) {            this.money = money;            this.gaga = gaga;        }        public PM() { }    }

　　

3. Access Modifier

Public

Private

Protected

 

 

In java, if you use the protected access modifier to modify a variable, all classes in the current package can be accessed. Add different packages

Classes with inheritance relationships can also be accessed.

4. Secret subclass Construction

1. Main Function

2. Subclass construction, not entering the subclass construction body

3. Execute to the parent class constructor and do not enter the parent class constructor.

4. Execute the parent class constructor to create the parent class Object

5. Return to the subclass constructor for execution.

6. The subclass constructor is executed to construct the subclass object.

7. Return to Main and continue subsequent code execution.

5. base (parent class Construction)

First usage of base: use attribute base. attribute name

Second usage of base; Use method base. The method name is the same

Third usage of base: Call the parent class to construct base ()

// Base. attribute name

  class SE:PM    {        public int n;        public SE(int i,int n,int m){            base.gaga = i;        }    }

// Base. Method Name

 base.show();

// Call the parent class construction

 public SE(int i,int n,int m):base(){            base.gaga = i;            base.show();        }

　　

6. Inheritance and uniqueness

C # does not support multi-Inheritance

Java does not support multi-inheritance. You can use interfaces to support multi-inheritance in disguise.

Multi-implementation //////////////// disguised multi-inheritance Interface

Machine language

Underlying ++ driver level of Assembly Language

Process-driven level ++ drive disc dll

C # Object-Oriented Java does not support multi-Inheritance

7. Preliminary Polymorphism

Polymorphism: Multiple Forms

Different objects have different responses to the same operation. Polymorphism.

For example:

1. USB parent USB mouse/USB keyboard/USB Lighting

2. Duck real duck/Rubber Duck wood duck (not called)

3. CUT doctors/hairdressers/actors

4. greeting in english/Korean

5. Transportation Vehicles/subway/bicycles

The parent class has a Cut method, and the subclass has a Cut method with the same name.

How to satisfy polymorphism Conditions

 

Parent class: Person

Subclass A: Hairdresser barber

Subclass B: Doctor

Subclass C: Actor

Implement polymorphism Conditions

1. The parent class has a method modified with the virtual keyword.

2. The subclass must have a method with the same name. The Override keyword is used.

3. Add N subclass objects to the parent class type set ..

4. iterative