barcode generator project in vb.net Figure 19-2. Generics and user-defined types in Visual C#.NET

Printer ECC200 in Visual C#.NET Figure 19-2. Generics and user-defined types

Figure 19-2. Generics and user-defined types
Data Matrix 2d Barcode Drawer In Visual C#
Using Barcode generator for .NET framework Control to generate, create Data Matrix 2d barcode image in Visual Studio .NET applications.
www.OnBarcode.com
DataMatrix Recognizer In Visual C#.NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
GENERICS
European Article Number 13 Creator In C#
Using Barcode generator for VS .NET Control to generate, create EAN 13 image in .NET applications.
www.OnBarcode.com
Data Matrix ECC200 Generation In C#
Using Barcode generation for .NET Control to generate, create DataMatrix image in Visual Studio .NET applications.
www.OnBarcode.com
Continuing with the Stack Example
QR Code Creation In Visual C#.NET
Using Barcode maker for Visual Studio .NET Control to generate, create Quick Response Code image in Visual Studio .NET applications.
www.OnBarcode.com
Matrix Barcode Generation In Visual C#.NET
Using Barcode creation for .NET Control to generate, create Matrix image in .NET framework applications.
www.OnBarcode.com
In the stack example, with classes MyIntStack and MyFloatStack, the bodies of the declarations of the classes are identical except at the positions dealing with the type of the value held by the stack. In MyIntStack, these positions are occupied by type int. In MyFloatStack, they are occupied by float. You can create a generic class from MyIntStack by doing the following: Take the MyIntStack class declaration, and instead of substituting float for int, substitute the type placeholder T. Change the class name to MyStack. Place the string <T> after the class name.
Generate PDF 417 In C#
Using Barcode creator for Visual Studio .NET Control to generate, create PDF-417 2d barcode image in .NET applications.
www.OnBarcode.com
ITF Maker In Visual C#.NET
Using Barcode creation for .NET Control to generate, create Interleaved 2 of 5 image in .NET applications.
www.OnBarcode.com
The result is the following generic class declaration. The string consisting of the angle brackets with the T means that T is a placeholder for a type. (It doesn t have to be the letter T it can be any identifier.) Everywhere throughout the body of the class declaration where T is located, an actual type will need to be substituted by the compiler. class MyStack <T> { int StackPointer = 0; T [] StackArray; public void Push(T x ) {...} public T Pop() {...} ... }
DataMatrix Printer In Java
Using Barcode drawer for Eclipse BIRT Control to generate, create Data Matrix ECC200 image in Eclipse BIRT applications.
www.OnBarcode.com
DataMatrix Drawer In .NET Framework
Using Barcode encoder for Reporting Service Control to generate, create Data Matrix ECC200 image in Reporting Service applications.
www.OnBarcode.com
GENERICS
Encode QR-Code In Visual Studio .NET
Using Barcode maker for Reporting Service Control to generate, create Quick Response Code image in Reporting Service applications.
www.OnBarcode.com
Data Matrix Creation In .NET
Using Barcode maker for Reporting Service Control to generate, create ECC200 image in Reporting Service applications.
www.OnBarcode.com
Generic Classes
Barcode Printer In None
Using Barcode creator for Online Control to generate, create Barcode image in Online applications.
www.OnBarcode.com
Code-39 Scanner In Java
Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
Now that you ve seen a generic class, let s look at generic classes in more detail and see how they re created and used. As you know, there are two steps for creating and using your own regular, nongeneric classes: declaring the class and creating instances of the class. But generic classes are not actual classes but templates for classes so you must first construct actual class types from them. You can then create references and instances from these constructed class types. Figure 19-3 illustrates the process at a high level. If it s not all completely clear yet, don t worry we ll cover each part in the following sections. 1. 2. 3. Declare a class, using placeholders for some of the types. Provide actual types to substitute in for the placeholders. This gives you an actual class definition, with all the blanks filled in. Create instances from the filled-in class definition.
Print Barcode In VS .NET
Using Barcode printer for .NET Control to generate, create Barcode image in .NET applications.
www.OnBarcode.com
Print Code 128 Code Set C In Java
Using Barcode maker for Android Control to generate, create ANSI/AIM Code 128 image in Android applications.
www.OnBarcode.com
Figure 19-3. Creating instances from a generic type
EAN13 Drawer In .NET
Using Barcode drawer for .NET framework Control to generate, create UPC - 13 image in .NET framework applications.
www.OnBarcode.com
Barcode Maker In Java
Using Barcode generator for Eclipse BIRT Control to generate, create Barcode image in Eclipse BIRT applications.
www.OnBarcode.com
GENERICS
Matrix Barcode Creation In Visual Studio .NET
Using Barcode maker for ASP.NET Control to generate, create 2D image in ASP.NET applications.
www.OnBarcode.com
Encoding PDF417 In VB.NET
Using Barcode maker for .NET framework Control to generate, create PDF-417 2d barcode image in .NET framework applications.
www.OnBarcode.com
Declaring a Generic Class
Declaring a simple generic class is much like declaring a regular class, with the following differences: Place a matching set of angle brackets after the class name. Between the angle brackets, place a comma-separated list of the placeholder strings that represent the types, to be supplied on demand. These are called type parameters. Use the type parameters throughout the body of the declaration of the generic class to represent the types that should be substituted in.
For example, the following code declares a generic class called SomeClass. The type parameters are listed between the angle brackets and then used throughout the body of the declaration as if they were real types. Type parameters class SomeClass < T1, T2 > { Normally, types would be used in these positions. public T1 SomeVar = new T1(); public T2 OtherVar = new T2(); } Normally, types would be used in these positions. There is no special keyword that flags a generic class declaration. Instead, the presence of the type parameter list, demarcated with angle brackets, distinguishes a generic class declaration from a regular class declaration.
GENERICS
Creating a Constructed Type
You cannot create class objects directly from a generic class. First, you need to tell the compiler what actual types should be substituted for the placeholders (the type parameters). The compiler takes those actual types and creates a template from which it creates actual class objects. To construct a class type from a generic class, list the class name and supply real types between the angle brackets, in place of the type parameters. The real types being substituted for the type parameters are called type arguments. Type arguments SomeClass< short, int > The compiler takes the type arguments and substitutes them for their corresponding type parameters throughout the body of the generic class, producing the constructed type from which actual class instances are created. Figure 19-4 shows the declaration of generic class SomeClass on the left. On the right, it shows the constructed class created by using the type arguments short and int.
Figure 19-4. Supplying type arguments for all the type parameters of a generic class produces a constructed class from which actual class objects can be created. Figure 19-5 illustrates the difference between type parameters and type arguments. Generic class declarations have type parameters, which act as placeholders for types. Type arguments are the actual types you supply when creating a constructed type.
Copyright © OnBarcode.com . All rights reserved.