Error Checking Vb.net
resources Windows Server 2012 resources Programs MSDN subscriptions Overview Benefits Administrators Students Microsoft Imagine Microsoft Student Partners ISV Startups TechRewards Events Community Magazine Forums Blogs Channel 9 Documentation APIs and reference Dev centers Retired content Samples We’re sorry. The content you requested has been removed. You’ll be auto redirected in 1 second. Developing with Visual Studio .NET Articles and Columns Visual Basic .NET Articles Visual Basic .NET Articles Introduction to Exception Handling in Visual Basic .NET Introduction to Exception Handling in Visual Basic .NET Introduction to Exception Handling in Visual Basic .NET Accessing the Registry with Visual Basic .NET Adding New Features with User Controls Advanced Features in Visual Basic .NET and Testing for Scalability Around the World with Visual Basic Aspect-Oriented Programming Asynchronous Execution in Visual Basic .NET Asynchronous Method Execution Using Delegates Automatically Generating Proxy Classes Automatically Generating a Web Service Automating COM+ Administration Best Practices for Windows Forms Applications Building an Attribute Documenter and Viewer Building a Progress Bar that Doesn't Progress Calling All Operators Can I Interest You in 5000 Classes? COM+ and MTS, DCOM and MSMQ, Serialization in .NET Compile Options, Loading Images into PictureBoxes, Deploying .NET Apps, and More Create a Graphical Editor Using RichTextBox and GDI+ Creating A Breadcrumb Control Creating a Five-Star Rating Control Creating and Managing Secondary Threads Creating a Product Search Application Using the eBay SDK and Visual Basic .NET Creating Markup Text in Visual Basic .NET Creating Your Own Dynamic Properties and Preserve Property Settings in Visual Basic .NET Data Binding Radio Buttons to a List Data Binding in Visual Basic .NET Deploying Hybrid Visual Basic 6.0 / Visual Basic .NET Applications Deployment Changes in Visual Basic .NET Deploying Assemblies Design an Application Migration Strategy for Visual Basic 6.0 to Visual Basic 2005 Designing With Custom Attributes Diagnose This: Launching and Controlling System Processes with Visual Basic 6 and the .NET Framework Digital Grandma Doing Async the Easy Way Don't Freak Out About Visual Studio Enterprise Services, SQL Script Editing Environmental Awareness: Accessing Operating System Information, Special Folders, and More with Visual Basic 6 and the .NET Framework Exploiting New Language Features in Visual Basic .NET, Part 2 Exploring the Visual Basic .NET Resource Kit Extracting Data fr
VB.Net - Program Structure VB.Net - Basic Syntax VB.Net - Data Types VB.Net - Variables VB.Net - Constants VB.Net - Modifiers VB.Net - Statements VB.Net - Directives VB.Net - Operators VB.Net - Decision Making VB.Net - Loops VB.Net - Strings VB.Net - Date & Time VB.Net - Arrays VB.Net - Collections VB.Net - Functions VB.Net - Subs VB.Net - Classes & Objects VB.Net - Exception Handling VB.Net - File Handling VB.Net - Basic Controls VB.Net - Dialog Boxes VB.Net - Advanced Forms VB.Net - Event Handling https://msdn.microsoft.com/en-us/library/aa289505(v=vs.71).aspx VB.Net Advanced Tutorial VB.Net - Regular Expressions VB.Net - Database Access VB.Net - Excel Sheet VB.Net - Send Email VB.Net - XML Processing VB.Net - Web Programming VB.Net Useful Resources VB.Net - Quick Guide VB.Net - Useful Resources VB.Net - Discussion Selected Reading Developer's Best Practices Questions and Answers Effective Resume Writing HR Interview Questions Computer Glossary Who is https://www.tutorialspoint.com/vb.net/vb.net_exception_handling.htm Who VB.Net - Exception Handling Advertisements Previous Page Next Page An exception is a problem that arises during the execution of a program. An exception is a response to an exceptional circumstance that arises while a program is running, such as an attempt to divide by zero. Exceptions provide a way to transfer control from one part of a program to another. VB.Net exception handling is built upon four keywords: Try, Catch, Finally and Throw. Try: A Try block identifies a block of code for which particular exceptions will be activated. It's followed by one or more Catch blocks. Catch: A program catches an exception with an exception handler at the place in a program where you want to handle the problem. The Catch keyword indicates the catching of an exception. Finally: The Finally block is used to execute a given set of statements, whether an exception is thrown or not thrown. For example, if you open a file, it must be closed whether an exception is raised or not. Throw: A program throws an except
for Beginners Try ... Catch in VB .NET This lesson is part of an ongoing tutorial. The previous part is here: Runtime Errors VB.NET has a inbuilt class that deals with errors. The Class is http://www.homeandlearn.co.uk/NET/nets5p4.html called Exception. When an exception error is found, an Exception object is created. The coding http://www.codeproject.com/Articles/13658/VB-NET-Error-Handling structure VB.NET uses to deal with such Exceptions is called the Try Catch structure. In the coding area for your button, type the word Try. Then hit the return key on your keyboard. VB.NET completes the rest of the structure for you: Try Catch ex As Exception End Try The Try word means "Try to execute this code". The Catch word means error checking "Catch any errors here". The ex is a variable, and the type of variable it is is an Exception object. Move your line of code from the previous section to the Try part: Try rt1.LoadFile("C:\test10.txt", RichTextBoxStreamType.PlainText) Catch ex As Exception End Try When you run your programme, VB will Try to execute any code in the Try part. If everything goes well, then it skips the Catch part. However, if an error occurs, VB.NET jumps straight to Catch. Add error checking vb.net the following to your Catch part: MessageBox.Show(ex.Message) Your coding window should look like this: Because ex is an object variable, it now has its own Properties and methods. One of these is the Message property. Run your programme and test it out. Click your button. You should see the following error message: The message is coming from the "additional Information" section of the error message we saw earlier, the one we didn't handle. But the point about this new message box is that it will not crash your programme. You have handled the Exception, and displayed an appropriate message for the user. If you know the kind of error that a programme might throw, you can get what Type it is from the Error message box you saw earlier. This one: Click the View Details links under Actions to see the following: The first line tells us the Type of Exception it is: System.IO.FileNotFoundException You can add this directly to the catch part. Previously, you were just catching any error that might be thrown: Catch ex As Exception But if you know a "file not found" error might be thrown, you can add that to the Catch line, instead of Exception: Catch ex As System.IO.FileNotFoundException You can keep the Exception line as well. (You can have as many Catch parts as you want.) This will Catch any other errors that may occur: Try rt1.LoadFile("C:\tes
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