Скачать или смотреть How to Create a Boolean Function to Manage Objects in a Generic Collection

Learn how to effectively create a `Boolean function` in VB.NET to manage unique objects in a generic collection by ensuring no duplicates are added based on a specific attribute.
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This video is based on the question https://stackoverflow.com/q/63071109/ asked by the user 'Julen' ( https://stackoverflow.com/u/13987579/ ) and on the answer https://stackoverflow.com/a/63072056/ provided by the user 'Mary' ( https://stackoverflow.com/u/8367626/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding Boolean Functions in VB.NET for Generic Collections

Managing collections of objects in programming is a common task, especially when you want to ensure the uniqueness of items based on specific attributes. In this post, we'll specifically address a common challenge faced when using List(Of T) in VB.NET and how to create a Boolean function for checking the presence of an attribute before adding new objects to your collection.

The Problem: Managing Unique Attributes

Imagine you have a List(Of Aspirante) (representing applicants) and each applicant has a DNI – an identifier that must be unique. When attempting to add a new applicant to this list, your program needs to check if another applicant with the same DNI already exists. If it does, you should prevent this addition (returning True for duplication); if it doesn’t, you will allow the addition (returning False).

Here’s a simplified example of how your initial implementation might look like:

[[See Video to Reveal this Text or Code Snippet]]

The above code won’t work because Contains cannot properly check for the existence of DNI within a list of Aspirante objects. But don't worry, let's dive into how to fix this issue!

The Solution: Updating Your Function

Step 1: Create a List of DNIs

Instead of directly checking if the list contains an Aspirante object, we can create a separate list that contains just the DNI strings from each Aspirante. This makes it easy to check for duplicates.

Here’s how you can implement this:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Simplifying with a Dictionary

If you're open to modifying the data structure, using a Dictionary(Of String, Aspirante) can make your function much more efficient. This allows you to directly check for the key DNI without needing a separate list.

Here's how you can implement this:

[[See Video to Reveal this Text or Code Snippet]]

Why This Works

Efficiency: The use of a dictionary significantly reduces the overhead associated with searching through a list, especially as the amount of data grows.

Simplicity: The logic for checking and adding entries is clean and easy to follow.

Conclusion

In conclusion, ensuring that your object management system remains efficient and clear is vital in programming. By creating a Boolean function that verifies the uniqueness of an attribute, you can maintain the integrity of your data collection. Whether you choose to use a list of DNIs or transition to a dictionary, both methods have their own advantages.

Feel free to experiment with these code snippets in your own applications, and see how they can streamline the handling of collections in VB.NET!