【Kotlin】リサイクラービューでリスト表示【Androidアプリ開発】

class SampleAdapter(context: Context, private val onItemClicked: (TimeZone) -> Unit):
        RecyclerView.Adapter<SampleAdapter.SampleViewHolder>() {

    private val inflater = LayoutInflater.from(context)
    private val timeZones = TimeZone.getAvailableIDs().map {
        id -> TimeZone.getTimeZone(id)
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): SampleViewHolder {
        val view = inflater.inflate(R.layout.list_time_zone_row, parent, false)
        val viewHolder = SampleViewHolder(view)

        view.setOnClickListener {
            val position = viewHolder.adapterPosition
            val timeZone = timeZones[position]
            onItemClicked(timeZone)
        }
        return viewHolder
    }

    override fun getItemCount(): Int = timeZones.size

    override fun onBindViewHolder(holder: SampleViewHolder, position: Int) {
        val timeZone = timeZones[position]
        holder.timeZone.text = timeZone.id
    }

    class SampleViewHolder(view: View) : RecyclerView.ViewHolder(view) {
        val timeZone = view.findViewById<TextView>(R.id.timeZone)
    }

}

class MainActivity : AppCompatActivity() {

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

        
        val sampleAdapter = SampleAdapter(this) { timeZone ->
            Toast.makeText(this, timeZone.displayName, Toast.LENGTH_SHORT).show()
        }
        val gridManager = GridLayoutManager(this, 4)

        val recyclerView = findViewById<RecyclerView>(R.id.timeZoneList). apply {
            adapter = sampleAdapter
            layoutManager = gridManager
        }

    }
}

android:layout_width="80dp"
android:layout_height="80dp"

val screenWidthDp = resources.configuration.screenWidthDp // 追記
val spanCount:Int = screenWidthDp / 88 // 追記
val gridManager = GridLayoutManager(this, spanCount) // spanCountに修正