Kotlin RecyclerView onItemClick

Question

I trying to implement item click with RecyclerView about 2 days. I tried doing all that was suggested stackoverflow about this subject. I have no any ideas already what to do anymore. Therefore I want to ask you.

This is my code:

    class CustomAdapter(var data: List<DataSource>, val clickListener: OnWordItemClickListener):
RecyclerView.Adapter<CustomAdapter.ViewHolder>() {

    class ViewHolder(view: View) : RecyclerView.ViewHolder(view)
    {
        val tv_front: TextView = view.findViewById(R.id.tv_front) as TextView
        val tv_back: TextView = view.findViewById(R.id.tv_back) as TextView
        // Define the click listener
        fun initialize(dataSource: DataSource, action: OnWordItemClickListener)
        {
            tv_front.text = dataSource._front
            tv_back.text = dataSource._back

            itemView.setOnClickListener {
                action.onItemClick(dataSource, adapterPosition)
            }
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val view = LayoutInflater.from(parent.context).inflate(R.layout.row_item, parent, false)

        return ViewHolder(view)
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        /*val currentItem = data[position]
        holder.tv_front.text = currentItem._front
        holder.tv_back.text = currentItem._back*/

        holder.initialize(data[position], clickListener)
    }

    override fun getItemCount(): Int = data.size
}

interface OnWordItemClickListener
{
    fun onItemClick(dataSource: DataSource, position: Int)
}

And code from MainActivity:

    class MainActivity : AppCompatActivity(), OnWordItemClickListener {

    val PERMISSION_REQUEST_CODE: Int = 123
    private lateinit var linearLayoutManager: LinearLayoutManager
    lateinit var rv_allWords: RecyclerView
    lateinit var adapter: CustomAdapter
    lateinit var databaseHandler: DatabaseHandler
    lateinit var dataSource: DataSource

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        permissions()

        rv_allWords = findViewById(R.id.rv_allWords) as RecyclerView
        linearLayoutManager = LinearLayoutManager(this)
        rv_allWords.layoutManager = linearLayoutManager

        databaseHandler = DatabaseHandler(this)
        val exampleList = databaseHandler.read_from()
        adapter = CustomAdapter(exampleList, this)
        rv_allWords.adapter = adapter
        adapter.notifyDataSetChanged()
    }

    fun permissions()
    {
        //var permissionStatus = ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)

        if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) +
                ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE)
                == PackageManager.PERMISSION_GRANTED)
        {
            // permission granted
        } else {
            ActivityCompat.requestPermissions(this, arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.READ_EXTERNAL_STORAGE), PERMISSION_REQUEST_CODE)
        }
    }

    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        when(requestCode)
        {
            PERMISSION_REQUEST_CODE ->
            {
                if ((grantResults.isNotEmpty()) && grantResults[0] == PackageManager.PERMISSION_GRANTED && grantResults[1] == PackageManager.PERMISSION_GRANTED)
                {
                    // permissions is granted. Continue the action or workflow
                    Toast.makeText(this, "Permissions granted", Toast.LENGTH_SHORT).show()
                } else {
                    // Explain to the user that the feature is unavailable because
                    // the features requires a permission the the user has denied
                    val alertDialog: AlertDialog? = this?.let {
                        val builder = AlertDialog.Builder(it)
                        builder.apply {
                            setPositiveButton(R.string.OK, DialogInterface.OnClickListener { dialog, id ->
                                finish()
                                System.exit(0)
                            })
                            setMessage("The app needs to save some data to external storage.")
                        }
                        builder.show()
                    }
                }
                return
            }
            // Add other 'when' line to check for other
            // permissions this app might request
            else ->
            {
                // Ignore all other requests
            }
        }
    }
    fun generateTestList(size: Int): List<DataSource> {
        val list = ArrayList<DataSource>()

        for (i in 0 until size)
        {
            val item = DataSource(i, "Item $i", "$i")
            list += item
        }
        return list
    }

    override fun onCreateOptionsMenu(menu: Menu?): Boolean {
        menuInflater.inflate(R.menu.menu, menu)

        return super.onCreateOptionsMenu(menu)
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        var id = item.itemId

        if(id == R.id.menu_refresh)
        {

        }
        return super.onOptionsItemSelected(item)
    }

    override fun onResume() {
        super.onResume()
        databaseHandler.read_from()
    }

    override fun onItemClick(dataSource: DataSource, position: Int) {
        Toast.makeText(this, dataSource._back, Toast.LENGTH_SHORT).show()
        Log.i("onItemClick", dataSource._back)
    }
}

When I run the app on device or emulator, happens nothing. That is when I try to click on any item in RecyclerView, my message doesn't displayed and the app runs without errors. Sorry for my english. What else can i do?

Answer 1

1. Where is itemView defined? I may be wrong but you should change itemView for view inside initialize() method.

2. Try to implement View.OnClickListener with ViewHolder class.

    class ViewHolder(val view: View) : RecyclerView.ViewHolder(view), View.OnClickListener {
    //(...)
        fun initialize(dataSource: DataSource, action: OnWordItemClickListener)
            {
                tv_front.text = dataSource._front
                tv_back.text = dataSource._back
   
                view.setOnClickListener{action.onItemClick(dataSource, adapterPosition)}            
   
    }
   

---

UPDATE: So after investigating the rest of the code i found two LinearLayouts inside xml used for ViewHolder layout. I deleted the 'parent one' and it started working. Here is row_item.xml after changes.

<?xml version="1.0" encoding="utf-8"?>

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:orientation="horizontal"
        android:clickable="true"
        android:focusable="true"
        android:background="?attr/selectableItemBackground">

        <TextView
            android:id="@+id/tv_front"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:padding="3dp"
            android:text="Front"
            android:textSize="32sp"
            android:gravity="left"
            android:layout_weight="1" />

        <TextView
            android:id="@+id/tv_back"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:padding="3dp"
            android:text="Back"
            android:textSize="32sp"
            android:gravity="right"
            android:layout_weight="1" />

    </LinearLayout>