How to pass method as Action parameter | VB.Net

By: Rajesh P.S.

In VB.NET, you can pass an Action as a parameter to a method, allowing you to encapsulate a block of code that can be executed later. An Action is a delegate that represents a method with no parameters and no return value. This is particularly useful when you want to pass behavior or actions as data to methods or functions.

Action delegate

To use an Action delegate as a parameter, you must first create a method that matches the signature of the delegate. For example, the following code shows a method that matches the signature of the Action delegate:

Sub MyMethod() ' Do something. End Sub

Once you have created a method that matches the signature of the delegate, you can pass the method to another method as a parameter. For example, the following code shows how to pass the MyMethod() method to the DoSomethingWithAction() method:

Public Sub DoSomethingWithAction(ByVal action As Action) ' Call the action delegate. action.Invoke() End Sub ' Pass the `MyMethod()` method to the `DoSomethingWithAction()` method. DoSomethingWithAction(AddressOf MyMethod)

The AddressOf operator is used to return a delegate that references the specified method.

Here's a detailed explanation with examples:

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Defining an Action

You can define an Action that takes no parameters and performs a specific action, such as printing a message:

Dim printAction As Action = Sub() Console.WriteLine("Hello, World!")

Using an Action as a Parameter

You can pass this Action as a parameter to a method, allowing the method to execute it. Here's an example:

Sub PerformAction(action As Action) Console.WriteLine("Performing an action...") action() ' Execute the passed action End Sub ' Usage PerformAction(printAction) ' This will print "Hello, World!"

In this example, the PerformAction method accepts an Action as a parameter. When called with printAction, it executes the code block defined in the printAction delegate.

Anonymous Action

You can also create anonymous Action delegates directly as method parameters:

Sub PerformAnonymousAction(action As Action) Console.WriteLine("Performing an anonymous action...") action() ' Execute the anonymous action End Sub ' Usage PerformAnonymousAction(Sub() Console.WriteLine("This is an anonymous action.")) ' This will print the message.

Multiple Action Parameters

You can pass multiple Action parameters to a method, allowing you to execute different actions:

Sub PerformMultipleActions(action1 As Action, action2 As Action) Console.WriteLine("Performing multiple actions...") action1() ' Execute the first action action2() ' Execute the second action End Sub ' Usage PerformMultipleActions(Sub() Console.WriteLine("Action 1"), Sub() Console.WriteLine("Action 2"))

In this case, the method executes two different actions, as specified in the PerformMultipleActions method call.

Conclusion

You can pass an Action as a parameter to a method, allowing you to encapsulate and execute blocks of code as needed. An Action is a delegate representing a method with no parameters and no return value, making it a flexible way to pass behavior or actions as parameters to functions, enhancing code modularity and flexibility.

Next > VB.Net Predicate Delegate

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