リサイクラービューのサンプル

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リサイクラービュー、ややこしい。もっと簡単にならないものか。
絶対覚えてられないので、メモを残しておく。

表示だけ

* activity_main.xml*

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycleSampleView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

* row.xml*

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">


    <TextView
        android:id="@+id/custom_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />

</LinearLayout>

MainActivity.kt

package com.konishisoft.recyclertest

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.text.Layout
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import android.widget.Toast
import androidx.recyclerview.widget.DividerItemDecoration
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView

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

        //リサイクルビューの設定
        val recycleSampleView = findViewById<RecyclerView>(R.id.recycleSampleView)
        val layout = LinearLayoutManager(applicationContext)
        recycleSampleView.layoutManager = layout

        //データの登録
        val dataList = mutableListOf<String>("aaa", "bbb", "ccc")
        val adapter = RecyclerListAdapter(dataList)
        recycleSampleView.adapter = adapter

        //区切り線
        val decorator = DividerItemDecoration(applicationContext, layout.orientation)
        recycleSampleView.addItemDecoration(decorator)
    }

    /* ビューホルダクラス */
    private inner class RecyclerListViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        var customTextView : TextView

        init {
            customTextView = itemView.findViewById(R.id.custom_text)
        }

    }

    /* アダプタクラス */
    private inner class RecyclerListAdapter(private val listData:MutableList<String>):RecyclerView.Adapter<RecyclerListViewHolder>() {
        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerListViewHolder {
            val inflater = LayoutInflater.from(applicationContext)
            //row.xml取得
            val view = inflater.inflate(R.layout.row, parent, false)

            val holder = RecyclerListViewHolder(view)

            view.setOnClickListener {
                val menu =it.findViewById<TextView>(R.id.custom_text)
                Toast.makeText(applicationContext, menu.text, Toast.LENGTH_SHORT).show()
            }
            return holder
        }

        override fun onBindViewHolder(holder: RecyclerListViewHolder, position: Int) {
            val item = listData[position]
            holder.customTextView.text = item.toString()
        }

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

    }
}

実行結果