kotlin SharedPreferences Generic MutableList 읽기, 쓰기.

https://stackoverflow.com/questions/7361627/how-can-write-code-to-make-sharedpreferences-for-array-in-android

stackoverflow 에 올라온 코드를 참조해 제네릭하게 만들어 봤습니다.

사용법은 아래와 같습니다.

val sharedPref = getSharedPreferences("config", MODE_PRIVATE)

setArrayPref<String>(sharedPref, "testList ", <<inList>> )

val testList = getArrayPref<String>(sharedPref, "testList")

fun <T> setArrayPref(prefs: SharedPreferences, key: String, values: MutableList<T>) {
    val editor = prefs.edit()
    val jArray = JSONArray()
    for (i in 0 until values.size) {
        jArray.put(values[i])
    }
    if (values.isNotEmpty()) {
        editor.putString(key, jArray.toString())
    } else {
        editor.putString(key, null)
    }
    editor.commit()
}

fun <T> getArrayPref(prefs: SharedPreferences, key: String): MutableList<T> {
    val json = prefs.getString(key, null)
    val list = mutableListOf<T>()
    if (json != null) {
        try {
            val a = JSONArray(json)
            for (i in 0 until a.length()) {
                val str = a.optString(i) as? T
                if (str != null) {
                    list.add(str)
                }
            }
        } catch (e: JSONException) {
            e.printStackTrace()
        }
    }
    return list
}