android - How to pass listener to an Adapter from a Fragment? (Kotlin)

Question

Im currently working on an app which has a Settings Activity. In this Settings Activity there is a FrameLayout which loads a fragment containing a RecyclerView.

In the fragment, i have to pass to the RecyclerView adapter a listener, which is needed for the OnItemClick function. I tried using context instead of this , but it doesnt work.

How do you correctly pass a listener to an Adapter?

Code:

FragmentSettings.kt

class FragmentSettingsMain : Fragment(), AdapterSettings.OnItemClickListener {
    val settingsList = listOf(
        DataItemsSettings(getString(R.string.look), getString(R.string.lookdescription), R.drawable.ic_colored_color_lens),
        DataItemsSettings(getString(R.string.playing), getString(R.string.playingdescription), R.drawable.ic_colored_view_carousel),
        DataItemsSettings(getString(R.string.images), getString(R.string.imagesdscription), R.drawable.ic_colored_image),
        DataItemsSettings(getString(R.string.audio), getString(R.string.audiodescription), R.drawable.ic_colored_volume_up),
        DataItemsSettings(getString(R.string.other), getString(R.string.otherdescription), R.drawable.ic_colored_shape),
        DataItemsSettings(getString(R.string.about), getString(R.string.aboutdescription), R.drawable.ic_colored_info)
    )

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        retainInstance = true
    }

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? = inflater.inflate(R.layout.fragment_settings_main, container, false)

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        rvSettings.apply {
            layoutManager = LinearLayoutManager(activity)
            adapter = AdapterSettings(settingsList, NEEDS LISTENER HERE)
        }
    }

    override fun OnItemClick(position: Int) {
        when(position) {
            0 -> //Start new fragment here
            1 -> //Start new fragment here
            2 -> //Start new fragment here
            3 -> //Start new fragment here
            4 -> //Start new fragment here
            5 -> this.startActivity(Intent(this, ActivityAbout::class.java))
        }
    }
}

AdapterSettings.kt

class AdapterSettings(
    var settingsList: List<DataItemsSettings>,
    var listener: OnItemClickListener
) : RecyclerView.Adapter<AdapterSettings.SettingsViewHolder>() {

    inner class SettingsViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView), View.OnClickListener {
        init {
            itemView.setOnClickListener(this)
        }

        override fun onClick(p0: View?) {
            val position : Int = adapterPosition
            if (position != RecyclerView.NO_POSITION) {
                listener.OnItemClick(position)
            }
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): SettingsViewHolder {
        val view = LayoutInflater.from(parent.context).inflate(R.layout.item_settings, parent, false)
        return SettingsViewHolder(view)
    }

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

    override fun onBindViewHolder(holder: SettingsViewHolder, position: Int) {
        holder.itemView.apply {
            rvTitle.text = settingsList[position].stringTitle
            rvDescription.text = settingsList[position].stringDescription
            rvIcon.setImageResource(settingsList[position].itemIcon)
        }
    }

    interface OnItemClickListener {
        fun OnItemClick(position: Int)
    }
}

Answer 1

As you are in apply block to use this you need to add @FragmentSettingsMain while using this.

AdapterSettings(settingsList,this@FragmentSettingsMain)

Or You can use

val listener  = this
rvSettings.apply{
  AdapterSettings(settingsList,listener)
}

Answer 2

您可以将 lambda 传递给适配器，调用adapter.onAction = {}