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How to implement undo functionality in a RecyclerView in Kotlin Android

How to implement undo functionality in a RecyclerView in Kotlin Android.

Here is a detailed step-by-step tutorial on how to implement undo functionality in a RecyclerView in Kotlin for Android:

Step 1: Setting up the project​

  • Create a new Android project in Kotlin.
  • Add the necessary dependencies in the app-level build.gradle file:
implementation 'androidx.recyclerview:recyclerview:1.2.1'
implementation 'androidx.cardview:cardview:1.0.0'

Step 2: Creating the RecyclerView layout​

  • Create a new layout file called item_list.xml to represent each item in the RecyclerView. This layout will contain the views you want to display for each item.
  • Add the necessary views and design the layout according to your requirements.

Step 3: Creating the Adapter class​

  • Create a new Kotlin class called ItemAdapter and make it extend RecyclerView.Adapter<ItemAdapter.ItemViewHolder>.
  • Implement the required methods: onCreateViewHolder, onBindViewHolder, and getItemCount.
  • In the onCreateViewHolder method, inflate the item_list.xml layout and return a new instance of ItemViewHolder.
  • In the onBindViewHolder method, bind the data to the views in the ItemViewHolder based on the item position.
  • In the getItemCount method, return the total number of items in your data source.

Step 4: Implementing the Undo functionality​

  • Inside the ItemAdapter class, create a method called removeItem that takes an Int parameter representing the position of the item to be removed.
  • In the removeItem method, store the removed item in a temporary variable.
  • Remove the item from your data source using the position parameter.
  • Notify the adapter that an item has been removed using notifyItemRemoved(position).
  • Create another method called restoreItem that takes the removed item as a parameter.
  • In the restoreItem method, insert the item back into the data source at the original position.
  • Notify the adapter that an item has been inserted using notifyItemInserted(position).

Step 5: Adding the Undo feature to the RecyclerView​

  • In your main activity layout, add a CoordinatorLayout as the root view.
  • Inside the CoordinatorLayout, add the RecyclerView that will display the items.
  • Below the RecyclerView, add a Snackbar with the message "Item removed" and an action button with the text "Undo".
  • In the main activity class, create an instance of the ItemAdapter and set it as the adapter for the RecyclerView.
  • In the onCreate method of the main activity, set a click listener on the action button of the Snackbar.
  • Inside the click listener, call the restoreItem method of the ItemAdapter and pass the removed item as a parameter.

That's it! You have successfully implemented the undo functionality in a RecyclerView in Kotlin for Android. Now, when the user swipes to remove an item, a Snackbar will appear with the option to undo the action.