Bài giảng Lập trình C# 2010: Chương 5 - String Class có nội dung trình bày về: Constructor, String Field, String Operators, String Methods, DEMO String & Dictionary.
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Nội dung Text: Bài giảng Lập trình C# 2010: Chương 5 - ĐH Công nghệ Đồng Nai
- DONG NAI UNIVERSITY OF TECHNOLOGY
- DONG NAI UNIVERSITY OF TECHNOLOGY
- DONG NAI UNIVERSITY OF TECHNOLOGY
Abstraction
Encapsulation
Inheritance
Polymorphism
- DONG NAI UNIVERSITY OF TECHNOLOGY
Abstraction
Characteristics
Properties
Object
Behaviors
Methods
- DONG NAI UNIVERSITY OF TECHNOLOGY
Encapsulation
Characteristic
Behaviors
s
Methods
Properties
Package
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Encapsulation
private
protected
public
- DONG NAI UNIVERSITY OF TECHNOLOGY
Inheritance
• The ability to create a new class
from an existing class
• The existing class is called the
base, superclass, or parent
• The inherited class is called the
derived, subclass, or child
• A derived class has an “is a”
relationship with its base class
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Inheritance
- DONG NAI UNIVERSITY OF TECHNOLOGY
Inheritance
• Inheritance supports reusability
• Reusability – creation of object
functionality that may be used in multiple
projects
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Polymorphism
• Methods with identical names have
different implementations
• The Select method is different for radio
buttons, check boxes, and list boxes
• Allows a single class to have more than one
method with different argument lists
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How to create Class
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Class Name
Constructors
Attributes
Properties
Methods
- public abstract class CAbstractProductDONG NAI UNIVERSITY OF TECHNOLOGY
{ private string m_strID;
private string m_strName; Attributes
private string m_strDescription;
public CAbstractProduct() { } Constructor
public string ID
{
get { return this.m_strID; }
set { this.m_strID = value; }
}
public string Name
{
get { return this.m_strName; } Properties
set { this.m_strName = value; }
}
public string Description
{
get { return
this.m_strDescription; }
set { this.m_strDescription = value;
}
} Methods
- DONG NAI UNIVERSITY OF TECHNOLOGY
public class CProduct :
CAbstractProduct
{
private double m_dPrice;
public CProduct()
{ }
public double Price
{
get { return this.m_dPrice;
}
set { this.m_dPrice =
value; }
}
public override void doSomething()
{
- public class CBook:CProduct DONG NAI UNIVERSITY OF TECHNOLOGY
{
private string m_strISBN;
private string m_strAuthor;
private string m_strTitle;
public CBook()
{
}
public string ISBN
{
get { return this.m_strISBN; }
set { this.m_strISBN = value; }
}
public string Author
{
get { return this.m_strAuthor; }
set { this.m_strAuthor = value; }
}
public string Title
{
get { return this.m_strTitle; }
set { this.m_strTitle = value; }
}
}
- DONG NAI UNIVERSITY OF TECHNOLOGY
public class CCompactDisc:CProduct
{
private string m_strArtist;
private string m_strTitle;
public CCompactDisc()
{ }
public string Artist
{
get { return this.m_strArtist; }
set { this.m_strArtist = value; }
}
public string Title
{
get { return this.m_strTitle; }
set { this.m_strTitle = value; }
}
public override void doSomething()
{
throw new NotImplementedException();
}
}
- DONG NAI UNIVERSITY OF TECHNOLOGY
public class CTravelGuide:CBook
{
private string m_strCountry;
public CTravelGuide()
{ }
public string Country
{
get { return this.m_strCountry;
}
set { this.m_strCountry =
value; }
}
}
- DONG NAI UNIVERSITY OF TECHNOLOGY
Garbage Collection
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• Operator new allocates memory
• When objects are no longer referenced, the
CLR performs garbage collection
• Garbage collection helps avoid memory leaks
(running out of memory because unused
memory has not been reclaimed)
• Allocation and deallocation of other resources
(database connections, file access, etc.) must be
explicitly handled by programmers
- DONG NAI UNIVERSITY OF TECHNOLOGY
• Use finalizers in conjunction with the garbage
collector to release resources and memory
• Before garbage collector reclaims an object’s
memory, it calls the object’s finalizer
• Each class has only one finalizer (also called
destructor)
• Name of a destructor is the ~ character,
followed by the class name
• Destructors do not receive any arguments
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