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Raise Error Vb.net

You can use the Throw statement to trap errors within your code because Visual Basic moves up the call stack until it finds the appropriate exception-handling code. Display an XmlNode contents in a DataGrid? By using a throw statement inside a catch block, we can change the resulting exception. Ken is a Technical Editor for Access/VB/SQL Advisor magazine and Contributing Editor for Informant Communication Group's Microsoft Office Solutions magazine. this contact form

System.DivideByZeroException Handles errors generated from dividing a dividend with zero. How to: Throw an Exception in Visual Basic Visual Studio 2010 Other Versions Visual Studio 2008 Visual Studio 2005 This example throws an ApplicationException exception.Example VB Copy Throw New ApplicationException ' ExitHere: ' Perform cleanup code here. ' Disregard errors in this ' cleanup code. Private Sub ThrowException() Dim lngSize As Long Dim s As FileStream ' Catch an exception thrown by the called procedure.

In the .NET Framework documentation, you'll find tables listing all the possible exceptions that might occur when you call any method. You can create an exception intentionally, called raising an exception, with the Visual Basic Err object's Raise method, which is declared this way internally in VB .NET: Raise(ByVal Number As Integer, If you want to preserve the current error trap, set up a different one, and then return back to the first one. Each example uses this code to do its job, retrieving the file name from a text box on the sample form, txtFileName: Copy Dim lngSize As Long ' Length is 64-bit

Listing 2. A Try/Catch block is placed around the code that might generate an exception. if (args.Length == 0) { throw new ArgumentException("No parameter found"); } } VB.Net Private Shared Sub Main(args As String()) 'If there is no parameter found.. The following table provides some of the predefined exception classes derived from the Sytem.SystemException class: Exception Class Description System.IO.IOException Handles I/O errors.

Private Sub SimpleException() Dim lngSize As Long Dim s As FileStream ' Display the entire contents of the Exception object. The code in the Finally block runs after the exception-handling code, but before control returns back to the calling procedure. The content you requested has been removed. at ...

You can pass in no parameters (you'll get a generic Exception object, with default values for its properties); a string indicating the error message you want sent back to the caller; Try TestThrow() Catch e As FileNotFoundException MessageBox.Show("Error occurred: " & e.Message) ' Use e.InnerException to get to error ' that triggered this one. Use Try…Catch blocks to anticipate and handle possible exceptions.See AlsoTasksHow to: Catch an Exception in Visual BasicHow to: Test Code with a Try…Catch Block in Visual BasicHow to: Clean up Resources Main topics include Try/Catch blocks, Exception objects, procedure callers, and how to create your own Exception classes. (17 printed pages) Objectives Compare error handling in Microsoft® Visual Basic® .NET to that

Some of the exception classes derived from the System.Exception class are the System.ApplicationException and System.SystemException classes. VB.Net exception handling is built upon four keywords: Try, Catch, Finally and Throw. Private Sub MultipleExceptions() Dim lngSize As Long Dim s As FileStream Try s = File.Open(txtFileName.Text, FileMode.Open) lngSize = s.Length s.Close() Catch e As ArgumentException MessageBox.Show( _ "You specified an invalid filename. As astander mentioned below, it's probably because it is so trivial and easily answered elsewhere. –Jonathon Reinhart Oct 31 '12 at 12:39 add a comment| 1 Answer 1 active oldest votes

So the exceptions defined by the programmers should derive from this class. http://lebloggeek.com/raise-error/raise-error-in-vb-6-0.html These error handling blocks are implemented using the Try, Catch and Finally keywords. That is, when processing multiple Catch blocks, when the runtime first finds a match where the current exception meets the "is a" rule for the exception trapped by the Catch block, Here's what you see when you run this console application: Error number 51 occurred: Application-defined or object-defined error.

The Exception class provides information about the runtime error, as shown in Table 1. Catch ' Handle exceptions that occur within ' the Try block, here. It contains the name of the methods on the current call stack, along with the file name and line number where the exception was thrown for each method. http://lebloggeek.com/raise-error/raise-error-in-vb-net.html Join them; it only takes a minute: Sign up How to raise exception in VB.NET?

It uses the first block it finds that matches. Listing 1. If it can't find any appropriate Catch block all the way up the call stack, the runtime handles the exception itself (as shown earlier in Figure 2).

For each case, try entering the path to a file that doesn't exist, or a drive that doesn't exist, or a drive that doesn't contain any media, or any other path

Dev centers Windows Office Visual Studio Microsoft Azure More... Have a look at Throw Statement (Visual Basic) The Throw statement throws an exception that you can handle with structured exception-handling code (Try...Catch...Finally) or unstructured exception-handling code (On Error GoTo). Why include a Finally block if you don't include a Catch block? Although this isn't generally considered to be an exception condition, it may be an error condition within your application.

Because each level inherits from the class defined above it, each lower level is an instance of the type specified above it. MessageBox.Show( _ "The drive you selected is not ready. " & _ "Make sure the drive contains valid media.") Catch e As Exception MessageBox.Show("An unknown error occurred.") End Try End Sub Example of Exception Imports System.Text Public Class ThrowTest Public Shared Sub fn(ByVal age As Int32) If age < 0 Then Throw New ArgumentOutOfRangeException("Age Can Not Be his comment is here That is, a Finally block without Catch blocks is fine.

Tip You can also use the Visual Basic Error statement to raise an error like this: Error errnumber. Do I need to turn off camera before switching auto-focus on/off? The "is a" appears in quotes here, because it's a meaningful operator—when you have multiple Catch blocks, those blocks match against the current exception using an "is a" rule. This documentation is archived and is not being maintained.

Conclusion Hope this article would have helped you in understanding Throw Statement in VB.NET Related Articles CheckBox Control in VB.NET Exception in VB.NET Control Statements in VB.NET: Part 1 Control Statements Structured exception handling provides several features that offer more flexible error handling than in previous versions of Visual Basic: Error handling in .NET is based on the Exception class, which contains In addition, the details aren't something you want your user to see. Try s = File.Open(txtFileName.Text, FileMode.Open) lngSize = s.Length s.Close() Catch e As Exception Throw (New FileNotFoundException( _ "Unable to open the specified file.", e)) End Try End Sub Running Code Unconditionally

That is, when a procedure throws an exception, it can nest another exception inside the exception it's raising, passing both exceptions out to the caller. In Visual Basic .NET, this involves adding additional Catch blocks for each error you'd like to trap individually. PRIVACY POLICY | TERMS & CONDITIONS | CONTACT US | REPORT ABUSE Measuring Information Content of unannotated terms in a corpus, avoiding -log(0) Fantasy Story about Phantom Tollbooth/Where the Wild Things Are kids as Adults Which lane to enter on this roundabout? (UK)

Raising an Error The next several examples use the same basic premise—your goal is to open a file, retrieve its length, and then close the file. See ASP.NET Ajax CDN Terms of Use – http://www.asp.net/ajaxlibrary/CDN.ashx. ]]> Developer Network Developer Network Developer Sign in MSDN subscriptions Message Error message text.