SharedPref2

package ドメイン.sharedpref2

import android.content.Context

import android.content.SharedPreferences

import androidx.appcompat.app.AppCompatActivity

import android.os.Bundle

import android.view.View

import android.widget.Toast

import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    companion object {

        const val PREF_FILE_NAME = "record"

        const val PREF_SET_KEY = "scores"

    }

    private lateinit var preferences: SharedPreferences

    private val initBtnListener = View.OnClickListener {

        val scores = listOf(

            Score("Geri", 71),

            Score("Enoch", 82),

            Score("Pamela", 62),

            Score("Cornelius", 100),

            Score("Joanna", 59)

        )

        listView.adapter = ScoreAdapter(this, scores)

    }

    private val saveBtnListener = View.OnClickListener {

        val adapter = listView.adapter as ScoreAdapter

        val scores = adapter.scores

        val data = mutableSetOf<String>()

        for (score in scores) {

            // データを文字列にして Set<String> に add する

            data.add(score.toString())

        }

        // SharedPref に保存する

        preferences.edit().putStringSet(PREF_SET_KEY, data).apply()

        Toast.makeText(this, "保存しました", Toast.LENGTH_SHORT).show()

    }

    private fun showData() {

        val scoresSet = preferences.getStringSet(PREF_SET_KEY, null)

        if (scoresSet != null) {

            val scores = mutableListOf<Score>()

            for (score in scoresSet) {

                scores.add(Score.fromString(score))

            }

            listView.adapter = ScoreAdapter(this, scores)

        }

    }

    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_main)

        preferences = getSharedPreferences(PREF_FILE_NAME, Context.MODE_PRIVATE)

        btnInit.setOnClickListener(initBtnListener)

        btnSave.setOnClickListener(saveBtnListener)

        // SharedPreferences から読み込んでデータを表示させる

        showData()

    }

}

package ドメイン.sharedpref2

data class Score(val name: String, val score: Int) {

    companion object {

        /**

         * Score インスタンスを作成する FactoryMethod

         * @param score "NAME,SCORE" -> CSV 形式の文字列

         */

        fun fromString(score: String): Score {

            val array = score.split(",")

            return Score(array[0], array[1].toInt())

        }

    }

    override fun toString(): String {

        return "$name,$score"

    }

}

package ドメイン.sharedpref2

import android.content.Context

import android.view.LayoutInflater

import android.view.View

import android.view.ViewGroup

import android.widget.BaseAdapter

import android.widget.TextView

class ScoreAdapter(

    private val context: Context,

    val scores: List<Score>

) : BaseAdapter() {

    override fun getView(position: Int, convertView: View?, parent: ViewGroup?): View {

        val view = convertView ?: createView(parent)

        val item = getItem(position)

        (view.tag as ViewHolder).run {

            name.text = item.name

            item.score.toString()

        }

        return view

    }

    override fun getItem(position: Int) = scores[position]

    override fun getItemId(position: Int) = position.toLong()

    override fun getCount() = scores.size

    private fun createView(parent: ViewGroup?): View {

        val view = LayoutInflater.from(context).inflate(

            R.layout.list_item_row,

            parent,

            false

        )

        view.tag = ViewHolder(view)

        return view

    }

    private class ViewHolder(view: View) {

        val name: TextView = view.findViewById(R.id.txtName)

        val score: TextView = view.findViewById(R.id.txtScore)

    }

}