Can any one tell me how to work with recyclerview on click listener in kotlin

Question

This is the code for the activity where the rows will be shown

class doctors : AppCompatActivity() {

override fun onCreate(savedInstanceState: Bundle?) {

    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_doctors)

    val recyclerView = findViewById<RecyclerView>(R.id.docrecview)


    recyclerView.layoutManager = LinearLayoutManager(this)


    val docs = ArrayList<DocData>()





    val btn_click_me = findViewById<Button>(R.id.consult_btn)

    btn_click_me.setOnClickListener {
        Toast.makeText(this, "You clicked me.", Toast.LENGTH_SHORT).show()
    }


    val TAG = "My message"
    val db = FirebaseFirestore.getInstance()
//calling data from firebase to populate rows
    db.collection("doctors")
        .get()
        .addOnSuccessListener { result ->
            for (document in result) {
                Log.d(TAG, "${document.id} => ${document.data}")
                docs.add(DocData(document.data["name"].toString(), document.data["specialization"].toString()))

            }
            recyclerView.adapter = Adapter(docs)


        }
        .addOnFailureListener { exception ->
            Log.d(TAG, "Error getting documents: ", exception)
        }




}

And this is the adapter

class Adapter (val doctorlist: ArrayList<DocData>) : RecyclerView.Adapter<Adapter.ViewHolder>() {

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): Adapter.ViewHolder {
    val v = LayoutInflater.from(parent?.context).inflate(R.layout.user_row, parent, false)
    return ViewHolder(v)


}

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

override fun onBindViewHolder(holder: Adapter.ViewHolder, position: Int) {
    val doc:DocData = doctorlist[position]

    holder.txtname.text =  doc.name
    holder.txtSpec.text = doc.specialization

}

class ViewHolder(itemView: View) :RecyclerView.ViewHolder(itemView){

    val txtname = itemView.findViewById<TextView>(R.id.textName)
    val txtSpec = itemView.findViewById<TextView>(R.id.major)
    val btn = itemView.findViewById<Button>(R.id.consult_btn)

}

}

The red marked area is a button in a recyclerview and I want to go to another activity by clicking on that button and I am not able to figure it out this is my learning phase I will be grateful if you guys will help Thankyou in advance

score 0 · Answer 1 · answered Mar 16 '20 at 22:08

See https://stackoverflow.com/a/58836873/2914140. You need to create an interface like:

public interface ClickListener {
    void onClick(int position);
}

There you can put any parameters, not only position. In activity/fragment implement the interface. Then call it from onBindViewHolder():

@Override
public void onBindViewHolder(holder: Adapter.ViewHolder, position: Int) {
     holder.textView1.setOnClickListener{
         clickListener.onClick(position));
     }
}

Also you need to set clickListener with a method or constructor of the adapter.

And what? It is very easy, a slight difference in this example. I also write in Kotlin (not in this case). — CoolMind, Mar 17 '20 at 09:51

score 0 · Answer 2 · answered Mar 16 '20 at 23:50

You have two options. Either use interfaces or higher order function, I prefer the later. with functions you pass an onClick function that you invoke when your btn is clicked:

class Adapter(
    private val docList: List<DocData>,
    private val onClick: (DocData) -> Unit // a function that takes a DocData parameter
) : RecyclerView.Adapter<Adapter.ViewHolder>() {
    // ......

    override fun onBindViewHolder(holder: Adapter.ViewHolder, position: Int) {
        val doc: DocData = doctorlist[position]
        btn.setOnClickListener {
            onClick.invoke(doc)
        }
        //.....
    }

}

then pass a function when instantiating an Adapter:

Adapter(docs) { docData ->
    // btn was clicked in this docData
}

Hi there Mohamed, why do we need to pass the function through the adapter, rather than just defining it in the onBindViewHolder — Liam Baron, Mar 17 '21 at 22:21
You can't change the signature of `onBindVeiwHolder()` and you shouldn't call yourself . the owner of the `Adapter` object needs to pass the `onClick` function either with the constructor (like above) or with another setter function. — Mohamed Mohsin, Mar 18 '21 at 13:22

Can any one tell me how to work with recyclerview on click listener in kotlin

2 Answers2