Interface Syntax in .NET framework

Encoding PDF 417 in .NET framework Interface Syntax

Interface Syntax
Paint PDF-417 2d Barcode In Visual Studio .NET
Using Barcode maker for ASP.NET Control to generate, create PDF-417 2d barcode image in ASP.NET applications.
www.OnBarcode.com
Bar Code Maker In Visual Studio .NET
Using Barcode printer for ASP.NET Control to generate, create barcode image in ASP.NET applications.
www.OnBarcode.com
To declare an interface, you use the interface keyword instead of the class or struct keyword. Inside the interface, you declare methods exactly as in a class or a structure except that you never specify an access modi er (public, private, or protected), and you replace the method body with a semicolon. Here is an example:
PDF-417 2d Barcode Generation In C#.NET
Using Barcode maker for Visual Studio .NET Control to generate, create PDF 417 image in .NET framework applications.
www.OnBarcode.com
PDF 417 Generator In VS .NET
Using Barcode creation for VS .NET Control to generate, create PDF 417 image in .NET applications.
www.OnBarcode.com
interface IComparable { int CompareTo(object obj); }
Creating PDF417 In Visual Basic .NET
Using Barcode generation for Visual Studio .NET Control to generate, create PDF417 image in .NET applications.
www.OnBarcode.com
QR Code Creation In .NET
Using Barcode generator for ASP.NET Control to generate, create QR Code image in ASP.NET applications.
www.OnBarcode.com
Tip The Microsoft .NET Framework documentation recommends that you preface the name of your interfaces with the capital letter I. This convention is the last vestige of Hungarian notation in C#. Incidentally, the System namespace already de nes the IComparable interface as shown here.
Linear Printer In Visual Studio .NET
Using Barcode maker for ASP.NET Control to generate, create Linear 1D Barcode image in ASP.NET applications.
www.OnBarcode.com
Drawing Code 128 Code Set C In Visual Studio .NET
Using Barcode drawer for ASP.NET Control to generate, create Code 128B image in ASP.NET applications.
www.OnBarcode.com
13
Generate USS-128 In .NET
Using Barcode creation for ASP.NET Control to generate, create GS1-128 image in ASP.NET applications.
www.OnBarcode.com
UCC - 12 Encoder In VS .NET
Using Barcode creation for ASP.NET Control to generate, create UPC Code image in ASP.NET applications.
www.OnBarcode.com
Creating Interfaces and De ning Abstract Classes
Bar Code Maker In Visual Studio .NET
Using Barcode creator for ASP.NET Control to generate, create bar code image in ASP.NET applications.
www.OnBarcode.com
UCC - 12 Creation In Visual Studio .NET
Using Barcode encoder for ASP.NET Control to generate, create UCC - 12 image in ASP.NET applications.
www.OnBarcode.com
Interface Restrictions
UPC-A Supplement 2 Encoder In Visual Studio .NET
Using Barcode maker for Reporting Service Control to generate, create Universal Product Code version A image in Reporting Service applications.
www.OnBarcode.com
Generating Code 128C In VS .NET
Using Barcode encoder for Reporting Service Control to generate, create ANSI/AIM Code 128 image in Reporting Service applications.
www.OnBarcode.com
The essential idea to remember is that an interface never contains any implementation. The following restrictions are natural consequences of this: You re not allowed to de ne any elds in an interface, not even static ones. A eld is an implementation detail of a class or structure. You re not allowed to de ne any constructors in an interface. A constructor is also considered to be an implementation detail of a class or structure. You re not allowed to de ne a destructor in an interface. A destructor contains the statements used to destroy an object instance. (Destructors are described in 14, Using Garbage Collection and Resource Management. ) You cannot specify an access modi er for any method. All methods in an interface are implicitly public. You cannot nest any types (such as enumerations, structures, classes, or interfaces) inside an interface. An interface is not allowed to inherit from a structure or a class, although an interface can inherit from another interface. Structures and classes contain implementation; if an interface were allowed to inherit from either, it would be inheriting some implementation.
Printing Barcode In Java
Using Barcode creation for Java Control to generate, create barcode image in Java applications.
www.OnBarcode.com
GS1 - 13 Generator In C#.NET
Using Barcode generation for .NET framework Control to generate, create EAN 13 image in VS .NET applications.
www.OnBarcode.com
Implementing an Interface
Bar Code Encoder In Visual C#.NET
Using Barcode drawer for VS .NET Control to generate, create bar code image in Visual Studio .NET applications.
www.OnBarcode.com
QR Code Decoder In Visual C#
Using Barcode reader for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
To implement an interface, you declare a class or structure that inherits from the interface and implements all the methods speci ed by the interface. For example, suppose you are de ning the Mammal hierarchy shown in 12 but you need to specify that land-bound mammals provide a method named NumberOfLegs that returns as an int the number of legs that a mammal has. (Sea-bound mammals do not implement this interface.) You could de ne the ILandBound interface that contains this method as follows:
PDF-417 2d Barcode Encoder In None
Using Barcode generation for Software Control to generate, create PDF417 image in Software applications.
www.OnBarcode.com
Code 39 Extended Scanner In C#.NET
Using Barcode scanner for VS .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
interface ILandBound { int NumberOfLegs(); }
You could then implement this interface in the Horse class:
class Horse : ILandBound { ... int ILandBound.NumberOfLegs() { return 4; } }
Part II
Understanding the C# Language
When you implement an interface, you must ensure that each method matches its corresponding interface method exactly, according to the following rules: The method names and return types match exactly. Any parameters (including ref and out keyword modi ers) match exactly. The method name is prefaced by the name of the interface. This is known as explicit interface implementation and is a good habit to cultivate. All methods implementing an interface must be publicly accessible. However, if you are using explicit interface implementation, the method should not have an access quali er. If there is any difference between the interface de nition and its declared implementation, the class will not compile.
The Advantages of Explicit Interface Implementations
Implementing an interface explicitly can seem a little verbose, but it does offer a number of advantages that help you to write clearer, more maintainable, and more predictable code. You can implement a method without explicitly specifying the interface name, but this can lead to some differences in the way the implementation behaves. Some of these differences can cause confusion. For example, a method de ned by using explicit interface implementation cannot be declared as virtual, whereas omitting the interface name allows this behavior. It s possible for multiple interfaces to contain methods with the same names, return types, and parameters. If a class implements multiple interfaces with methods that have common signatures, you can use explicit interface implementation to disambiguate the method implementations. Explicit interface implementation identi es which methods in a class belong to which interface. Additionally, the methods for each interface are publicly accessible, but only through the interface itself. We will look at how to do this in the upcoming section Referencing a Class Through Its Interface. In this book, I recommend implementing an interface explicitly wherever possible.
A class can extend another class and implement an interface at the same time. In this case, C# does not denote the base class and the interface by using keywords as, for example, Java does. Instead, C# uses a positional notation. The base class is named rst, followed by
Copyright © OnBarcode.com . All rights reserved.