Snipet to read file from asset/internal storage on Android with Kotlin

ContextExts.kt

import android.content.Context
import com.google.gson.Gson
import com.google.gson.reflect.TypeToken

/**
 * Created by Hoa Vo on 1/18/19.
 */
fun Context.readAssetAsString(fileName: String): String = this.assets.open(fileName).use {
        String(it.readBytes())
}

inline fun <reified T: Any> Context.readAsset(fileName: String): T =
    Gson().fromJson(this.readAssetAsString(fileName), object: TypeToken<T>() {}.type)


fun Context.readFileAsString(fileName: String): String = this.openFileInput(fileName).use {
    String(it.readBytes())
}

inline fun<reified T: Any> Context.readFile(fileName: String): T =
    Gson().fromJson(this.readFileAsString(fileName), object: TypeToken<T>() {}.type)

fun Context.writeFile(fileName: String, data: Any){
    this.openFileOutput(fileName, Context.MODE_PRIVATE).use { it.write(Gson().toJson(data).toByteArray()) }
}


//Use
articles.addAll(context.readAsset("articles.json"))
...
context.writeFile("data.json", articles);