barcode printer vb.net InnerException in C#.NET

Printing Data Matrix in C#.NET InnerException

InnerException
Print Data Matrix ECC200 In C#.NET
Using Barcode generation for Visual Studio .NET Control to generate, create Data Matrix image in .NET applications.
www.OnBarcode.com
Scanning ECC200 In Visual C#.NET
Using Barcode reader for VS .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Message Source StackTrace TargetSite GetBaseException() ToString()
Linear Maker In Visual C#
Using Barcode generator for Visual Studio .NET Control to generate, create Linear 1D Barcode image in .NET applications.
www.OnBarcode.com
Data Matrix ECC200 Encoder In Visual C#.NET
Using Barcode generation for .NET Control to generate, create Data Matrix ECC200 image in .NET framework applications.
www.OnBarcode.com
When you are debugging an application, the most useful member is the ToString method, which returns a helpful string that contains pretty much all you need to know from the exception. Listing 14-9 contains an example of using this method. Listing 14-9. Using the Exception.ToString Method using System; class Listing 09 { static void Main(string[] args) { try { // define a loval variable string myLocalVar = null; // try to so something with the local variable Console.WriteLine("First letter: {0}", myLocalVar[0]); } catch (Exception ex) { Console.WriteLine("---Start of ToString() output---"); Console.WriteLine(ex); Console.WriteLine("---End of ToString() output---"); } // wait for input before exiting
Print UPC-A In Visual C#
Using Barcode creator for VS .NET Control to generate, create UPC-A Supplement 2 image in .NET framework applications.
www.OnBarcode.com
Barcode Encoder In Visual C#.NET
Using Barcode creator for .NET framework Control to generate, create Barcode image in .NET framework applications.
www.OnBarcode.com
CHAPTER 14 EXCEPTIONS
Create Matrix Barcode In C#
Using Barcode maker for .NET Control to generate, create Matrix image in VS .NET applications.
www.OnBarcode.com
MSI Plessey Drawer In C#
Using Barcode encoder for Visual Studio .NET Control to generate, create MSI Plessey image in VS .NET applications.
www.OnBarcode.com
Console.WriteLine("Press enter to finish"); Console.ReadLine(); } } In this exception, I cause an exception and then call the ToString method. I have printed out statements before and after the result of the ToString method. Compiling and running the code in Listing 14-9 produces the following results: ---Start of ToString() output--System.NullReferenceException: Object reference not set to an instance of an object. at Listing 09.Main(String[] args) in C:\Listing 09\Listing 09.cs:line 12 ---End of ToString() output--Press enter to finish This may not look like much, but it contains a wealth of information. First, it contains the type of the exception. In this example, it is NullReferenceException, and this is reported even though my catch clause is for System.Exception. Second, it contains a helpful descriptive message that tells me what may have caused the exception. Finally, it contains the stack trace. This isn t very long in such an example, but it does tell me that the problem occurred in line 12 of the Listing 09.cs file and within the Main method. We can get the individual parts of this string using the individual members of the Exception class. Listing 14-10 provides a demonstration. This can be more useful than calling ToString if you want to selectively log information about an exception, rather than performing debugging. Listing 14-10. Using the Members of the System.Exception Class using System; class Listing 10 { static void Main(string[] args) { try { // define a loval variable string myLocalVar = null; // try to so something with the local variable Console.WriteLine("First letter: {0}", myLocalVar[0]); } catch (Exception ex) { Console.WriteLine("Type: {0}", ex.GetType()); Console.WriteLine("Message: {0}", ex.Message); Console.WriteLine("Stack: {0}", ex.StackTrace); } // wait for input before exiting Console.WriteLine("Press enter to finish");
Creating Data Matrix In C#.NET
Using Barcode generator for VS .NET Control to generate, create Data Matrix 2d barcode image in VS .NET applications.
www.OnBarcode.com
Reading ECC200 In C#.NET
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
CHAPTER 14 EXCEPTIONS
Encode Barcode In VS .NET
Using Barcode creator for .NET Control to generate, create Barcode image in .NET applications.
www.OnBarcode.com
Paint Data Matrix 2d Barcode In VS .NET
Using Barcode creation for .NET framework Control to generate, create ECC200 image in Visual Studio .NET applications.
www.OnBarcode.com
Console.ReadLine(); } } Compiling and running the code in Listing 14-10 produces the following output: Type: System.NullReferenceException Message: Object reference not set to an instance of an object. Stack: at Listing 10.Main(String[] args) in C:\Listing 10\Listing 10.cs:line 12 Press enter to finish
Read Code 128A In Visual Basic .NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
Making Code39 In Objective-C
Using Barcode generation for iPhone Control to generate, create Code 39 image in iPhone applications.
www.OnBarcode.com
Using finally Clauses
Create PDF-417 2d Barcode In Visual Basic .NET
Using Barcode creator for .NET framework Control to generate, create PDF-417 2d barcode image in .NET framework applications.
www.OnBarcode.com
USS-128 Creator In None
Using Barcode maker for Word Control to generate, create EAN / UCC - 14 image in Microsoft Word applications.
www.OnBarcode.com
The way that control can jump around in a try statement can cause problems for some programs. This is especially true if you need to release resources or reset the state of your program whether an exception is thrown and handled. You can do this by adding a finally clause to your try statement, as shown in Listing 14-11. Listing 14-11. Using a finally Clause in a try Statement using System; class Listing 11 { static void Main(string[] args) { // allocate the resources AllocateResources(); try { // statements which uses the resources // and which may cause an exception Console.WriteLine("Perform work..."); // define a loval variable string myLocalVar = null; if (true) { // try to so something with the local variable Console.WriteLine("First letter: {0}", myLocalVar[0]); } } catch (NullReferenceException ex) { // handle this kind of exception Console.WriteLine("Exception: {0}", ex.GetType()); } finally {
PDF-417 2d Barcode Decoder In .NET
Using Barcode scanner for .NET framework Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Code 128 Code Set C Printer In Objective-C
Using Barcode creation for iPad Control to generate, create Code 128C image in iPad applications.
www.OnBarcode.com
CHAPTER 14 EXCEPTIONS
Drawing ANSI/AIM Code 128 In VB.NET
Using Barcode drawer for .NET framework Control to generate, create Code 128 Code Set A image in Visual Studio .NET applications.
www.OnBarcode.com
EAN13 Generator In Java
Using Barcode encoder for Java Control to generate, create EAN13 image in Java applications.
www.OnBarcode.com
Console.WriteLine("Finally clause executed"); // release the resources ReleaseResources(); } // wait for input before exiting Console.WriteLine("Press enter to finish"); Console.ReadLine(); } static void AllocateResources() { Console.WriteLine("Allocated Resources"); } static void ReleaseResources() { Console.WriteLine("Release Resources"); } } In this example, there are two methods that represent allocating and releasing resources: AllocateResources and ReleaseResources. There are lots of scenarios where you need to make sure to release a resource whether or not an exception is thrown. One of the most common is opening and closing a connection to a database. The AllocateResources method is called before the try statement, which would usually contain statements that use the allocated resources and that may throw an exception. In my example, I have defined, but not initialized, a local variable called myLocalVar. When the condition in the if statement is true, a statement is executed that causes a NullReferenceException to be thrown. Compiling and running the code in Listing 14-11 produces the following results: Allocated Resources Perform work... Exception: System.NullReferenceException Finally clause executed Release Resources Press enter to finish You can see that when the exception is thrown the statements in the catch clause are executed, followed by those in the finally clause. In the example, this means calling the ReleaseResources method so that any allocated resources can be released promptly for use by others. We can change the condition of the if statement to false like this: if (false) { // try to so something with the local variable Console.WriteLine("First letter: {0}", myLocalVar[0]); } The change prevents the statement that causes the exception from being executed. Compiling and running the modified code produces the following results:
Copyright © OnBarcode.com . All rights reserved.