Kotlin OnItemClickListener for a RecyclerView inside a Fragment - kotlin

Question

The problem is related to the fact that I don't manage to implement a OnItemClick listener for a RecyclerView that is located in a "mainFragment" by implementing the OnClickListener in the Adapter.
I would like my application (kotlin) to launch another fragment ("deletePage" in the code bellow) everytime an itemView (an ImageView) from the RecyclerView is clicked, this fragment would display the same photo in big.
My Adapter code is the following one:
class MyAdapter : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
private var photo = emptyList<Photo>()
inner class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
return MyViewHolder(
LayoutInflater.from(parent.context).inflate(R.layout.row_layout, parent, false)
)
}
override fun getItemCount(): Int {
return photo.size
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
holder.itemView.longitude.text = photo[position].latitude
holder.itemView.latitude.text = photo[position].longitude
holder.itemView.imageView.load(photo[position].photo)
}
fun setData(photo: List<Photo>) {
this.photo = photo
notifyDataSetChanged()
}
}
And my mainFragment code is the following one:
class MainFragment : Fragment(){
private lateinit var myView: MyViewModel
private val adapter by lazy { MyAdapter() }
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
val view = inflater.inflate(R.layout.fragment_main, container, false)
//Recyclerview
val adapter = MyAdapter()
val recyclerView = view.recycler_view
recyclerView.adapter = adapter
recyclerView.layoutManager = LinearLayoutManager(requireContext())
myView = ViewModelProvider(this).get(MyViewModel::class.java)
myView.readPhoto.observe(viewLifecycleOwner, Observer {photo ->
adapter.setData(photo)
})
setHasOptionsMenu(true)
return view
}
override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
inflater.inflate(R.menu.menu_database, menu)
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
when {
item.itemId == R.id.deleteAll -> findNavController().navigate(R.id.deletePage)
item.itemId == R.id.refresh -> {
Toast.makeText(activity, "yep", Toast.LENGTH_SHORT).show()
instertDataToDatabase()
}
}
if (item.itemId == R.id.deleteAll) {
}
return super.onOptionsItemSelected(item)
}
}
The objective is that when you click on an item of the RecyclerView the "findNavController().navigate(R.id.deletePage)" fragment is displayed but everytime I try to implement a solution the application crashes when clicking at an item of the RecyclerView. Right now the navigation works by the click on a button in the Menu at the toolbar but is not the ideal solution.
Any sort of help or advice would be very much appreciated!

Answer 1

Firstly you need to give click listener of your itemView in onBindViewHolder
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
holder.itemView.longitude.text = photo[position].latitude
holder.itemView.latitude.text = photo[position].longitude
holder.itemView.imageView.load(photo[position].photo)
holder.itemView.setOnClickListener { navigateToFragment() }
}
For the navigation somehow you should have a context instance.
Here is the possible solutions that came up to my mind:
Give navigator instance to adapter
class Navigator(fragment: Fragment) {
private val fragmentRef = WeakReference(fragment)
fun navigate(){
// make your navigations here with using fragmentRef.get()
}
}
In your fragment:
private val navigator = Navigator(this)
...
val adapter = MyAdapter(navigator)
In your adapter:
class MyAdapter(private val navigator: Navigator) : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
fun navigateToFragment(){
navigator.navigate()
}
Make interface for callback
2.1. Implement that interface in fragment and give adapter the interface instance
interface Navigable{
fun navigate()
}
In your fragment:
class MainFragment : Fragment(), Navigable{
...
override fun navigate(){
// make your navigation
}
val adapter = MyAdapter(navigator)
In your adapter:
class MyAdapter(private val navigable: Navigable) : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
fun navigateToFragment(){
navigable.navigate()
}
2.2. Make the interface, but do not pass reference, use findFragment in adapter
In your adapter: override onAttachedToRecyclerView to find fragment
private lateinit var navigable: Navigable
override fun onAttachedToRecyclerView(recyclerView: RecyclerView) {
super.onAttachedToRecyclerView(recyclerView)
navigable = recyclerView.findFragment<Fragment>() as Navigable
}
fun navigateToFragment(){
navigable.navigate()
}