How to implement sticky footer in a RecyclerView in Kotlin Android

How to implement sticky footer in a RecyclerView in Kotlin Android.

Here's a step-by-step tutorial on how to implement a sticky footer in a RecyclerView in Kotlin for Android:

Step 1: Set up your project

1. Create a new project in Android Studio and choose Kotlin as the programming language.
2. Make sure you have the necessary dependencies added to your project. In your app-level build.gradle file, add the following dependencies:

implementation 'androidx.recyclerview:recyclerview:1.2.0'

Step 2: Create RecyclerView layout

1. Open the XML layout file where you want to add the RecyclerView.
2. Add a RecyclerView element to your layout file:

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/recyclerView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_above="@+id/footer"
    app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />

3. Create a separate XML layout file for the footer view:

<LinearLayout
    android:id="@+id/footer"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <!-- Add your footer views here -->

</LinearLayout>

Step 3: Create ViewHolder and Adapter

1. Create a new Kotlin class file for your ViewHolder:

class ItemViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
    // Define your ViewHolder views here
}

2. Create a new Kotlin class file for your Adapter:

class ItemAdapter(private val items: List<Item>) : RecyclerView.Adapter<ItemViewHolder>() {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ItemViewHolder {
        val itemView = LayoutInflater.from(parent.context).inflate(R.layout.item_layout, parent, false)
        return ItemViewHolder(itemView)
    }

    override fun onBindViewHolder(holder: ItemViewHolder, position: Int) {
        val item = items[position]
        // Bind the item data to the ViewHolder views
    }

    override fun getItemCount(): Int {
        return items.size
    }
}

Step 4: Implement sticky footer

1. In your activity or fragment, initialize the RecyclerView and set the adapter:

val recyclerView: RecyclerView = findViewById(R.id.recyclerView)
val layoutManager = LinearLayoutManager(this)
recyclerView.layoutManager = layoutManager

// Assuming you have a list of items
val items = listOf<Item>(/* your items here */)

val adapter = ItemAdapter(items)
recyclerView.adapter = adapter

2. Create a new class for the RecyclerView ItemDecoration:

class StickyFooterItemDecoration(private val footer: View) : RecyclerView.ItemDecoration() {
    override fun onDrawOver(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {
        super.onDrawOver(c, parent, state)

        val childCount = parent.childCount
        val lastVisiblePosition = (parent.layoutManager as LinearLayoutManager).findLastVisibleItemPosition()

        // Check if the last visible item is the footer
        if (lastVisiblePosition == parent.adapter?.itemCount?.minus(1)) {
            val lastVisibleChild = parent.getChildAt(childCount - 1)
            if (lastVisibleChild.bottom >= parent.height - footer.height) {
                // The footer is partially or fully visible, adjust its position
                val translationY = lastVisibleChild.bottom - (parent.height - footer.height)
                footer.translationY = translationY.toFloat()
            }
        } else {
            // The footer is not visible, reset its position
            footer.translationY = 0f
        }
    }
}

3. Apply the StickyFooterItemDecoration to your RecyclerView:

val footer: View = findViewById(R.id.footer)
val itemDecoration = StickyFooterItemDecoration(footer)
recyclerView.addItemDecoration(itemDecoration)

That's it! You have now implemented a sticky footer in a RecyclerView in Kotlin for Android. The footer will stick to the bottom of the screen and adjust its position based on the visibility of the last item in the RecyclerView.