barcode printer vb.net GARBAGE COLLECTION in C#.NET

Drawer Data Matrix ECC200 in C#.NET GARBAGE COLLECTION

CHAPTER 18 GARBAGE COLLECTION
Make Data Matrix In Visual C#
Using Barcode generator for .NET framework Control to generate, create ECC200 image in VS .NET applications.
www.OnBarcode.com
Read Data Matrix ECC200 In Visual C#
Using Barcode scanner for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Implementing a Destructor
Print Code 128C In Visual C#.NET
Using Barcode printer for .NET framework Control to generate, create Code128 image in VS .NET applications.
www.OnBarcode.com
Generate Barcode In C#
Using Barcode creator for VS .NET Control to generate, create Barcode image in VS .NET applications.
www.OnBarcode.com
Some objects need to perform actions before they can be safely destroyed; the most common examples are where connections to databases and other servers need to be explicitly closed. The actions you take will depend on your object, but whatever it is you need to do can be included in a destructor. A destructor is a special method that is called after the garbage collector has identified an object as being unused but before it is deleted from memory. Listing 18-2 contains a class with a destructor. Listing 18-2. Defining a Class Destructor using System; class MyClass { public MyClass() { // constructor statements Console.WriteLine("Constructor called"); } ~MyClass() { // destructor statements Console.WriteLine("Destructor called"); } } A class destructor is a special method that is named after the class that it destructs, prepended with a tilde character (~), as illustrated by Figure 18-1.
Generating 1D In C#.NET
Using Barcode printer for VS .NET Control to generate, create 1D image in VS .NET applications.
www.OnBarcode.com
Generate Barcode In C#
Using Barcode generator for Visual Studio .NET Control to generate, create Barcode image in .NET framework applications.
www.OnBarcode.com
Figure 18-1. The anatomy of a destructor When you define a destructor, you must not use an access modifier or add parameters to the method. In the code statement block, you can add statements to release any resources and generally tidy up prior to the destruction of your object. Here is a simple example that causes the destructor to be called: using System; class DestructorTest { static void Main(string[] args) {
Print Data Matrix 2d Barcode In Visual C#.NET
Using Barcode generation for VS .NET Control to generate, create DataMatrix image in VS .NET applications.
www.OnBarcode.com
Uniform Symbology Specification Code 93 Creation In C#
Using Barcode maker for .NET Control to generate, create USS-93 image in .NET framework applications.
www.OnBarcode.com
CHAPTER 18 GARBAGE COLLECTION
Print Data Matrix 2d Barcode In .NET
Using Barcode maker for Reporting Service Control to generate, create Data Matrix ECC200 image in Reporting Service applications.
www.OnBarcode.com
Paint DataMatrix In None
Using Barcode generator for Online Control to generate, create Data Matrix ECC200 image in Online applications.
www.OnBarcode.com
// create a new MyClass object, but don't assign // it to a variable or field new MyClass(); // manually invoke the GC GC.Collect(); // wait for input before exiting Console.WriteLine("Press enter to finish"); Console.ReadLine(); } } This code creates a new MyClass object but doesn t assign it to a local variable or field. This means that there are no references to the object, and it will be identified as a candidate for destruction by the garbage collector, which I explicitly call. The results of compiling and running these statements are as follows: Constructor called Press enter to finish Destructor called The garbage collector runs in the background of a .NET process, which is why the output from the destructor method comes after the Press enter to finish output.
Reading Barcode In .NET Framework
Using Barcode decoder for .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
European Article Number 13 Creation In Visual Studio .NET
Using Barcode drawer for ASP.NET Control to generate, create GTIN - 13 image in ASP.NET applications.
www.OnBarcode.com
Destructors vs. Finalizers
Barcode Encoder In None
Using Barcode creator for Office Excel Control to generate, create Barcode image in Microsoft Excel applications.
www.OnBarcode.com
Code 128C Generation In Objective-C
Using Barcode maker for iPad Control to generate, create Code 128 Code Set C image in iPad applications.
www.OnBarcode.com
If you read the C# and .NET documentation, you will come across the term finalizer, which is used in much the same way as the term destructor. The confusion arises because .NET objects can be written in a range of languages (C#, VB.NET, and so on). All of these objects inherit a method called Finalize, which is called by the garbage collector immediately prior to an object s destruction. This is known as finalizing an object. This is a .NET feature that applies to all .NET languages. C# implements finalization using destructors. C# objects are not allowed to override the Finalize method and must implement a destructor instead. The C# compiler interprets a destructor and uses the code statements it contains to create a Finalize method for your class automatically. As an example, when the C# compiler sees a destructor like this: ~MyClass() { // destructor statements Console.WriteLine("Destructor called"); } it converts it to a Finalize method like this: protected override void Finalize() { try { // destructor statements
Code-39 Encoder In None
Using Barcode creator for Software Control to generate, create Code 39 image in Software applications.
www.OnBarcode.com
Painting Code 128 In None
Using Barcode generator for Online Control to generate, create USS Code 128 image in Online applications.
www.OnBarcode.com
CHAPTER 18 GARBAGE COLLECTION
Painting GS1 - 13 In None
Using Barcode creation for Excel Control to generate, create GTIN - 13 image in Microsoft Excel applications.
www.OnBarcode.com
Recognizing Code 128 Code Set B In VB.NET
Using Barcode decoder for .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
Console.WriteLine("Destructor called"); } finally { base.Finalize() } } You can see from this that your destructor doesn t need to call the Finalize method and that you can ignore the directive in the documentation to call the base class implementation of the Finalize method (because this is done for you when your destructor is compiled).
Barcode Printer In None
Using Barcode generator for Software Control to generate, create Barcode image in Software applications.
www.OnBarcode.com
PDF 417 Generation In None
Using Barcode generator for Font Control to generate, create PDF417 image in Font applications.
www.OnBarcode.com
Problems with Destructors
Destructors must be used with care; there are some important considerations explained in the following sections.
Performance Impact
The first problem with destructors is that they have an impact on the performance of the garbage collector, which has to stop and perform the code statements your constructor contains. For this reason, you should not use destructors that are empty (that is, that do not contain code statements) and should use destructors only when they are essential.
Copyright © OnBarcode.com . All rights reserved.