Develop Reference

current item Position in RecyclerView with interface Android

Here I am not getting my current clicked item position. It some time shows incorrect position and some time make crash.
My Adapter Code is as below.
Some time I clicked in 1st position it will work fine. But I clicked again at any position from the item it shows it's previous item.
Thanks in advance for your answer or suggestions.
class MyAdapter(private val mList: ArrayList<MyModel>) : RecyclerView.Adapter<MyAdapter.ViewHolder>() {
private lateinit var mListener: OnItemClickListener
interface OnItemClickListener : AdapterView.OnItemClickListener {
fun onItemClick(position: Int)
}
fun setOnItemClickListener(listener: OnItemClickListener) {
mListener = mListener
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.item_all_brands, parent, false)
return ViewHolder(view, mListener)
}
#SuppressLint("SetTextI18n")
#RequiresApi(Build.VERSION_CODES.N)
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.ivBrandImage.setImageResource(mList[position].image)
holder.tvBrandName.text = mList[position].name
holder.tvBrandName.isSelected = true
holder.tvBrandName.setSingleLine()
}
override fun getItemId(position: Int): Long {
return position.toLong()
}
override fun getItemCount(): Int {
return mList.size
}
class ViewHolder(ItemView: View, listener: OnItemClickListener) :
RecyclerView.ViewHolder(ItemView) {
val ivBrandImage: ImageView = itemView.findViewById(R.id.ivBrandImage)
val tvBrandName: TextView = itemView.findViewById(R.id.tvBrandName)
init {
itemView.setOnClickListener {
listener.onItemClick(adapterPosition)
}
}
}
}

There is one mistake you do in the setOnItemClickListener Method.
Remove :
fun setOnItemClickListener(listener: OnItemClickListener) {
mListener = mListener
}
Replace :
fun setOnItemClickListener(listener: OnItemClickListener) {
mListener = listener
}
So your total code should look like
class MyAdapter(private val mList: ArrayList<MyModel>) : RecyclerView.Adapter<MyAdapter.ViewHolder>() {
private lateinit var mListener: OnItemClickListener
interface OnItemClickListener : AdapterView.OnItemClickListener {
fun onItemClick(position: Int)
}
fun setOnItemClickListener(listener: OnItemClickListener) {
mListener = listener
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.item_all_brands, parent, false)
return ViewHolder(view, mListener)
}
#SuppressLint("SetTextI18n")
#RequiresApi(Build.VERSION_CODES.N)
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.ivBrandImage.setImageResource(mList[position].image)
holder.tvBrandName.text = mList[position].name
holder.tvBrandName.isSelected = true
holder.tvBrandName.setSingleLine()
}
override fun getItemId(position: Int): Long {
return position.toLong()
}
override fun getItemCount(): Int {
return mList.size
}
class ViewHolder(ItemView: View, listener: OnItemClickListener) :
RecyclerView.ViewHolder(ItemView) {
val ivBrandImage: ImageView = itemView.findViewById(R.id.ivBrandImage)
val tvBrandName: TextView = itemView.findViewById(R.id.tvBrandName)
init {
itemView.setOnClickListener {
listener.onItemClick(adapterPosition)
}
}
}
}

How to bind two xml in one class in android?

I'm new to Kotlin. I have a MainActivity and a list view inside.
When an item is clicked in the list view, I want to update a textView inside MainActivity.
However because data should be passed from ListView to MainActivity, I did something weird:
MainActivity.kt:
data class Country(val imgRes:Int, val name:String)
class MainActivity : AppCompatActivity() {
private lateinit var binding : ActivityMainBinding
private val data = arrayListOf<Country>()
val imgRes = intArrayOf()
val data1 = arrayOf()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
for(i in imgRes.indices) {
val country = Country(imgRes[i], data1[i])
data.add(country)
}
val adapter = RecyclerAdapter(data, object:RecyclerAdapter.OnItemClickListener {
override fun onItemClick(v: View, pos: Int) {
binding.textView.text = (v as TextView).text
}
})
binding.recycler1.adapter = adapter
binding.recycler1.layoutManager = StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL)
}
}
ListView.kt:
class RecyclerAdapter(private val dataSet:List<Country>, private val listener:OnItemClickListener) : RecyclerView.Adapter<RecyclerAdapter.ViewHolder>() {
public interface OnItemClickListener {
fun onItemClick(v:View, pos:Int)
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val binding = RowBinding.inflate(LayoutInflater.from(parent.context), parent, false)
return ViewHolder(binding)
}
override fun getItemCount(): Int {
return dataSet.size
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.bind(position)
}
inner class ViewHolder(val binding: RowBinding) : RecyclerView.ViewHolder(binding.root) {
val rowImageView = binding.rowImageView
val rowTextView = binding.rowTextView
init {
binding.root.setOnClickListener {
listener.onItemClick(rowTextView, adapterPosition)
}
}
fun bind(pos: Int) {
with(binding) {
rowImageView.setImageResource(dataSet[pos].imgRes)
rowTextView.text = dataSet[pos].name
}
}
}
}
I declared interface(OnItemClickListener) at ListView.kt and redefine it at MainActivity.kt.
It works fine but is there any better way to do this?

You can use higher order functions instead of interface.
Define this function top of your Adapter:
var onClick: ((text: String) -> Unit)? = null
in ViewHolder:
binding.root.setOnClickListener {
onClick?.invoke(dataSet[position].text)
}
in MainActivity:
adapter.onClick = { name ->
binding.textView.text = name
}
You can also find more information about higher orders in here

<include android:layout_width="match_parent"
android:layout_height="wrap_content"
layout="#layout/yourlayout" />

Try this in your Adapter:
var itemClickListener: ((position: Int, name: String) -> Unit)? = null
Bindviewholder:
itemClickListner.invoke(1,"anyvalue")
in Activity:
adapter.itemClickListener = {
position, name ->
Toast.makeText(requireContext(),"position is $position name is $name ",Toast.LENGTH_SHORT).show()
}

in Adapter:
private var mListener: OnItemClickListener,
interface OnItemClickListener {
fun onClick(position: Int, routerArray: ArrayList<Router>)
}
binding.yourView.setOnClickListener {
mListener.onClick(adapterPosition, routerArray)
}
in Activity:
override fun onClick(position: Int, yourArray: ArrayList<Model>) {
binding.textView.text = yourArray[position].text
}

Unable to update recyclerView using adapter

I'm trying to update the below recycler view to show the new data that input from the form in the second activity. However, its only showing the original list that I had in there. What am I doing wrong here?
Here is the main activity:
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
var workoutList = mutableListOf(
Workout("a","d","d","d"),
Workout("a","d","d","d"),
Workout("a","d","d","d")
)
val adaptor = WorkoutAdaptor(workoutList)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
binding.btnNext.setOnClickListener {
Intent(this, SecondActivity::class.java).also {
startActivity(it)
}
}
binding.recyclerView.adapter = adaptor
binding.recyclerView.layoutManager = LinearLayoutManager(this)
}
override fun onRestart() {
super.onRestart()
var workout = intent.getSerializableExtra("EXTRA_WORKOUT") as Workout
workoutList.add(workout)
adaptor.notifyDataSetChanged()
}
}
Here is the adapter:
class WorkoutAdaptor (
var workouts: List<Workout>
) : RecyclerView.Adapter<WorkoutAdaptor.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val workoutCardBinding = WorkoutCardBinding.inflate(
LayoutInflater.from(parent.context), parent, false)
return ViewHolder(workoutCardBinding)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.bind(workouts[position])
}
override fun getItemCount(): Int {
return workouts.size
}
inner class ViewHolder(private val workoutCardBinding: WorkoutCardBinding) :
RecyclerView.ViewHolder(workoutCardBinding.root) {
fun bind(workout: Workout) {
workoutCardBinding.tvWorkoutCard.text = workout.toString()
}
}
}
And here is the activity where I get the workout object from:
class SecondActivity : AppCompatActivity() {
private lateinit var binding: ActivitySecondBinding
lateinit var spWorkoutsPosition: String
lateinit var spIncrementsPosition: String
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivitySecondBinding.inflate(layoutInflater)
setContentView(binding.root)
binding.spWorkoutTypes.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
override fun onItemSelected(p0: AdapterView<*>?, p1: View?, p2: Int, p3: Long) {
spWorkoutsPosition = p0?.getItemAtPosition(p2) as String
}
override fun onNothingSelected(p0: AdapterView<*>?) {
}
}
binding.spIncrements.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
override fun onItemSelected(adapterView: AdapterView<*>?, view: View?, position: Int, id: Long) {
spIncrementsPosition = adapterView?.getItemAtPosition(position) as String
}
override fun onNothingSelected(p0: AdapterView<*>?) {
}
}
binding.btnSave.setOnClickListener {
val workoutName = binding.tvWorkoutName.text.toString()
val workoutType = spWorkoutsPosition.toString()
val workoutIncrement = spIncrementsPosition.toString()
val workoutRestTime = binding.etRestTime.text.toString()
val workout = Workout(workoutName, workoutType, workoutIncrement, workoutRestTime)
Intent(this, MainActivity::class.java).also {
it.putExtra("EXTRA_WORKOUT", workout)
startActivity(it)
}
}
}
}

As #John Doe commented you should probably use ActivityResultLauncher. refer here.
and as for the update issue the recommended way of implementing recyclerView's adapter is androidx.recyclerview.widget.ListAdapter. The ListAdapter handles addition and removal without the need to redraw the entire view, and even animate those changes.
here's the implementation for your adapter:
class WorkoutAdaptor :
ListAdapter<Workout, WorkoutAdaptor.ItemViewHolder>(DiffCallback()) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ItemViewHolder {
return ItemViewHolder(
ItemAutocompleteSearchResultBinding.inflate(
LayoutInflater.from(parent.context),
parent,
false
)
)
}
override fun onBindViewHolder(holder: ItemViewHolder, position: Int) {
holder.bind(position)
}
inner class ItemViewHolder(val binding: ItemAutocompleteSearchResultBinding) :
RecyclerView.ViewHolder(binding.root) {
fun bind(position: Int) {
binding.apply {
workoutCardBinding.tvWorkoutCard.text = getItem(position).toString()
}
}
}
private class DiffCallback : DiffUtil.ItemCallback<Workout>() {
override fun areContentsTheSame(oldItem: Workout, newItem: Workout): Boolean {
return oldItem == newItem
}
override fun areItemsTheSame(oldItem: Workout, newItem: Workout): Boolean {
return oldItem.param1 == newItem.param1 &&
oldItem.param2 == newItem.param2 &&
oldItem.param3 == newItem.param3 &&
oldItem.param4 == newItem.param4
}
}
}
then you only have to call,
adapter.submitList(workoutList)
after you update the workoutList and the ListAdapter handles the rest.
and also call the adapter.submitList() in onStart() or onResume() methods.

How Can I create Interface for ItemClickListener in Kotlin?

I am new to Android & Kotlin. I want to click my row and intent it to other activity. That's why I tried to create an interface in my Adapter but it does not work. How can I create it?
My adapter code:
class NoteAdapter(private val titleTextArray: ArrayList<String>, private val imageArray: ArrayList<String>) : RecyclerView.Adapter<NoteAdapter.NoteHolder>() {
class NoteHolder (view: View) : RecyclerView.ViewHolder(view) {
var recyclerTitleText: TextView ?= null
var recyclerImageView: ImageView ?= null
init {
recyclerTitleText = view.findViewById(R.id.recyclerTitleText)
recyclerImageView = view.findViewById(R.id.recyclerImage)
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): NoteHolder {
val inflater = LayoutInflater.from(parent.context)
val view = inflater.inflate(R.layout.recycler_row, parent, false)
return NoteHolder(view)
}
override fun onBindViewHolder(holder: NoteHolder, position: Int) {
holder.recyclerTitleText?.text = titleTextArray[position]
Picasso.get().load(imageArray[position]).into(holder.recyclerImageView)
}
override fun getItemCount(): Int {
return titleTextArray.size
}
}

With Kotlin, you could to use a lambda (higher order function) to fetch the user clicks in the holder. For example, a base approach could be the next:
class YourAdapter(
private val listener: (String) -> Unit
) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
private val yourDataList = emptyList<String>()
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.compound_checkbox_terms_layout, parent, false)
return YourViewHolder(view)
}
override fun getItemCount(): Int {
TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
}
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
}
private inner class YourViewHolder(view: View) : RecyclerView.ViewHolder(view) {
init {
if (adapterPosition != RecyclerView.NO_POSITION) {
val selectedData = yourDataList[adapterPosition]
listener.invoke(selectedData)
}
}
}
}

Pass the activity context to the adapter from Activity so it can launch intent
Activity Code :
mAdapter = new CustomAdapter(this, imageArray, ArrayList);
Adapter Code :
class NoteAdapter(private val titleTextArray: ArrayList, private val imageArray: ArrayList, private val context : Context) : RecyclerView.Adapter<NoteAdapter.NoteHolder>() {
class NoteHolder (view: View) : RecyclerView.ViewHolder(view) {
var recyclerTitleText: TextView?= null
var recyclerImageView : ImageView?= null
init {
recyclerTitleText = view.findViewById(R.id.recyclerTitleText)
recyclerImageView = view.findViewById(R.id.recyclerImage)
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): NoteHolder {
val inflater = LayoutInflater.from(parent.context)
val view = inflater.inflate(R.layout.recycler_row, parent, false)
return NoteHolder(view)
}
override fun onBindViewHolder(holder: NoteHolder, position: Int) {
holder.recyclerTitleText?.text = titleTextArray[position]
Picasso.get().load(imageArray[position]).into(holder.recyclerImageView)
holder.recyclerImageView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(context, NesneTani.class);
context.startActivity(intent);
}
});
}
override fun getItemCount(): Int {
return titleTextArray.size
}
}

Create an Interface to catch the click event. (position is optional)
interface OnItemClickListener {
fun onItemClick(position: Int)
}
add OnItemClickListener as a parameter in your Adapter class
class NoteAdapter(
private val titleTextArray: ArrayList<String>,
private val imageArray: ArrayList<String>,
private val listener: OnItemClickListener
) : RecyclerView.Adapter<NoteAdapter.NoteHolder>()
Then do below inside onBindViewHolder
override fun onBindViewHolder(holder: NoteHolder, position: Int) {
listener.onItemClick(position)
}
now inside your activity, implement the OnItemClickListener
class ActivityName implements OnItemClickListener{}
and while initiating adapter, do this
mAdapter = new CustomAdapter(this, imageArray, ArrayList);
Then inside the overridden method do what you want
override fun onItemClick(position: Int) {
//start the activity you want.
}

How to create onclick event in adapter using interface android?

How can I create on click event using interface?
In my application I've created view click interface to detect clicking on adapter items into parent activity. After creating interface and method into adapter how I can use this interface to call the view listener ?

Please check this code, It's working fine for me.
First Create Adapter class.
class ChapterAdapter(private val activity: Activity, val mWords: ArrayList<Chapter>, val btnlistener: BtnClickListener) : RecyclerView.Adapter<ChapterAdapter.ViewHolder>() {
companion object {
var mClickListener: BtnClickListener? = null
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
return ViewHolder(layoutInflater.inflate(R.layout.layout_capter_raw, parent, false))
}
override fun onBindViewHolder(holder: ViewHolder?, position: Int) {
mClickListener = btnlistener
val item = mWords[position]
holder.layout_chapter_name.setOnClickListener(object : View.OnClickListener {
override fun onClick(v: View?) {
if (mClickListener != null)
mClickListener?.onBtnClick(position)
}
})
}
override fun getItemCount(): Int {
return mWords.size
}
override fun getItemId(position: Int): Long {
return super.getItemId(position)
}
override fun getItemViewType(position: Int): Int {
return super.getItemViewType(position)
}
class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
val txt_capter_name = view.txt_capter_name
}
open interface BtnClickListener {
fun onBtnClick(position: Int)
}
}
After create and declare adapter in your Activity or Fragment.
listAdapter = ChapterAdapter(activity, _arrChapterList, object : ChapterAdapter.BtnClickListener {
override fun onBtnClick(position: Int, chapter_id: String, chapter_size: String, chapter_name: String) {
toast(chapter_id + " = " + chapter_size, Toast.LENGTH_LONG)
}
})

In Kotlin the proper way doing this, is using callbacks instead of Java Interfaces. Example:
class MyAdapter(private val callback: (YourModel) -> Unit) {
override fun onBindViewHolder(holder: DataBoundViewHolder<YourModel>, position: Int) {
bind(holder.binding, items!![position])
holder.binding.executePendingBindings()
holder.binding.root.setOnClickListener { callback(binding.model) }
}
}
And create the adapter somewhere using
MyAdapter myAdapter = MyAdapter( { println{"Clicked $it"} })
Edit: Since the Asker would like to see a full working code i used the code from Sumit and replaced the Interfaces with Kotlin-Callbacks.
class ChapterAdapter(private val activity: Activity,
val mWords: ArrayList<Chapter>,
val callback: (Any) -> Unit) :
RecyclerView.Adapter<ChapterAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
return ViewHolder(layoutInflater.inflate(R.layout.layout_capter_raw, parent, false))
}
override fun onBindViewHolder(holder: ViewHolder?, position: Int) {
val item = mWords[position]
holder.layout_chapter_name.setOnClickListener( callback {$it})
}
override fun getItemCount(): Int = mWords.size
override fun getItemId(position: Int): Long = super.getItemId(position)
override fun getItemViewType(position: Int): Int = super.getItemViewType(position)
class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
val txt_capter_name = view.txt_capter_name
}
and finally creating the Adapter
listAdapter = ChapterAdapter(activity, _arrChapterList, {
toast( "Clicked $it", Toast.LENGTH_LONG)
})

I have the same problem, and here is my solution:
package adapter
class MarketplaceListAdapter : RecyclerView.Adapter<MarketplaceListAdapter.ViewHolder> {
private val marketplaceList: ArrayList<Marketplace>
constructor(marketplaceList: ArrayList<Marketplace>) : super() {
this.marketplaceList = marketplaceList
}
private var listener: OnItemClickListener? = null
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
// implementation
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
// implementation
}
override fun getItemId(position: Int): Long {
return 0
}
override fun getItemCount(): Int {
return marketplaceList.size
}
fun setListener(listener: OnItemClickListener) {
this.listener = listener
}
interface OnItemClickListener {
fun onItemClick(marketplace: Marketplace)
}
inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView),
View.OnClickListener {
var tvTitle: TextView = itemView.findViewById(R.id.tvTitle)
var ivIcon: ImageView = itemView.findViewById(R.id.ivIcon)
init {
itemView.setOnClickListener(this)
}
override fun onClick(v: View) {
listener?.onItemClick(marketplaceList[adapterPosition])
}
}
}
And on my fragment:
val list = view.findViewById<RecyclerView>(R.id.list)
list?.let {
adapter?.let { adapter ->
list.adapter = adapter
adapter.setListener(object : MarketplaceListAdapter.OnItemClickListener {
override fun onItemClick(marketplace: Marketplace) {
onMarketplaceSelected(marketplace)
}
})
}
}