How to implement infinite scrolling in a ListView in Kotlin Android

How to implement infinite scrolling in a ListView in Kotlin Android.

Here is a detailed step-by-step tutorial on how to implement infinite scrolling in a ListView in Kotlin for Android.

Step 1: Set up the project

Start by creating a new Android project in Android Studio. Choose an appropriate project name and configure the project settings. Make sure you select Kotlin as the programming language.

Step 2: Add the necessary dependencies

Open the build.gradle file for your app module and add the following dependencies:

dependencies {
    // other dependencies
    implementation 'androidx.recyclerview:recyclerview:1.2.0'
}

Step 3: Create a layout file

Create a new layout file called item_list.xml to represent each item in the ListView. Customize it according to your requirements.

<!-- item_list.xml -->
<TextView
    android:id="@+id/itemTextView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textSize="18sp"
    android:padding="12dp" />

Step 4: Create a custom adapter

Create a new Kotlin class called CustomAdapter which extends the BaseAdapter class. This adapter will be responsible for populating the ListView with data.

class CustomAdapter(private val context: Context, private val itemList: ArrayList<String>) : BaseAdapter() {

    override fun getCount(): Int {
        return itemList.size
    }

    override fun getItem(position: Int): Any {
        return itemList[position]
    }

    override fun getItemId(position: Int): Long {
        return position.toLong()
    }

    override fun getView(position: Int, convertView: View?, parent: ViewGroup?): View {
        val view: View
        val viewHolder: ViewHolder

        if (convertView == null) {
            view = LayoutInflater.from(context).inflate(R.layout.item_list, parent, false)
            viewHolder = ViewHolder(view)
            view.tag = viewHolder
        } else {
            view = convertView
            viewHolder = view.tag as ViewHolder
        }

        val item = getItem(position) as String
        viewHolder.itemTextView.text = item

        return view
    }

    private class ViewHolder(view: View) {
        val itemTextView: TextView = view.findViewById(R.id.itemTextView)
    }
}

Step 5: Implement infinite scrolling

In order to implement infinite scrolling, you need to add a scroll listener to the ListView. This listener will detect when the user has reached the end of the list and load more data accordingly.

listView.setOnScrollListener(object : AbsListView.OnScrollListener {
    override fun onScrollStateChanged(view: AbsListView?, scrollState: Int) {
        // Not needed for infinite scrolling
    }

    override fun onScroll(
        view: AbsListView?,
        firstVisibleItem: Int,
        visibleItemCount: Int,
        totalItemCount: Int
    ) {
        if (firstVisibleItem + visibleItemCount == totalItemCount && totalItemCount != 0) {
            // Load more data
        }
    }
})

Step 6: Load more data

In the onScroll method of the scroll listener, you can add the logic to load more data. This can be done by appending new items to the existing list and notifying the adapter of the data change.

listView.setOnScrollListener(object : AbsListView.OnScrollListener {
    override fun onScrollStateChanged(view: AbsListView?, scrollState: Int) {
        // Not needed for infinite scrolling
    }

    override fun onScroll(
        view: AbsListView?,
        firstVisibleItem: Int,
        visibleItemCount: Int,
        totalItemCount: Int
    ) {
        if (firstVisibleItem + visibleItemCount == totalItemCount && totalItemCount != 0) {
            // Load more data
            val newData = loadMoreData()
            itemList.addAll(newData)
            customAdapter.notifyDataSetChanged()
        }
    }
})

private fun loadMoreData(): ArrayList<String> {
    // Simulate loading data from a data source
    val newData = ArrayList<String>()
    for (i in 0 until 10) {
        newData.add("Item ${itemList.size + i}")
    }
    return newData
}

Step 7: Set up the ListView

Finally, set up the ListView in your activity or fragment code. Create an instance of the CustomAdapter class and set it as the adapter for the ListView.

val itemList = ArrayList<String>()
val customAdapter = CustomAdapter(this, itemList)
listView.adapter = customAdapter

That's it! You have successfully implemented infinite scrolling in a ListView in Kotlin for Android. Now, when the user scrolls to the end of the list, more data will be loaded and displayed automatically.