Resolving RecyclerView Duplication Issues When Fetching Data from Room Database

In this guide, we'll address a common issue where a RecyclerView shows duplicated data fetched from a Room database. Learn how to ensure that your data is displayed correctly the first time it is loaded!
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: My RecyclerView fetching data from Room Database Again and again

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Fixing RecyclerView Duplicate Data Fetching from Room Database

When working with Android development, you might find yourself using a RecyclerView to display data fetched from a Room database. However, a common issue developers face is the retrieval of duplicate data each time they scroll. This can significantly affect the user experience, showing data multiple times instead of just once. In this guide, we'll explore how to tackle this problem and ensure that your RecyclerView displays data correctly.

The Problem

Imagine you have a RecyclerView in your app that's supposed to show a list of items pulled from a Room database. As you scroll, you notice that the items are being displayed repeatedly. This occurs despite the fact that you correctly insert the data into your database. The question is, how can we make sure that the data appears only once?

In the given example, even though items are inserted correctly into the Room database, the way data is observed and set in the RecyclerView causes repeated entries to show up.

Understanding the Solution

The solution to this problem involves ensuring that the list you're using to back your RecyclerView is cleared before you add new data. This means that every time new data is fetched, the old data should be cleared before appending the new items.

Step-by-Step Guide to Implementing the Fix

Clear the List Before Adding New Data: The crucial step is to clear newList each time new data is observed. This ensures the RecyclerView does not attempt to append new data to the existing list, which is what causes duplicates.

Modify getAllData() Method: Update the method responsible for fetching and setting data into the RecyclerView. Below is the revised code:

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

Rebind the Adapter: After clearing and populating newList, don't forget to call the method that binds the adapter to the RecyclerView to reflect the new changes.

Additional Considerations

Data Integrity: Make sure that the data being added is indeed correct and unique. You might want to add checks if your list inherently could have duplicates due to the insertion logic.

ListAdapter: If your list grows large or performance becomes a concern, consider using ListAdapter, which handles item animations and list updates more efficiently.

Visibility of Loading State: If you're fetching data asynchronously, consider implementing a loading state to enhance the user experience while data is being loaded.

Conclusion

In summary, if your RecyclerView is fetching and displaying duplicate data from the Room database, remember to clear the backing list (newList) before adding new items. This small change can dramatically enhance the user experience and ensure that your app behaves as expected.
With this approach, you can effectively manage and display the data loaded from your database without repetition. Happy coding!