Helper for shared preferences management - Kotlin version

PreferenceHelper.kt

package com.programacionymas.helpers

import android.content.Context
import android.content.SharedPreferences
import android.preference.PreferenceManager

object PreferenceHelper {

    fun defaultPrefs(context: Context): SharedPreferences
            = PreferenceManager.getDefaultSharedPreferences(context)

    fun customPrefs(context: Context, name: String): SharedPreferences
            = context.getSharedPreferences(name, Context.MODE_PRIVATE)

    private inline fun SharedPreferences.edit(operation: (SharedPreferences.Editor) -> Unit) {
        val editor = this.edit()
        operation(editor)
        editor.apply()
    }

    /**
     * puts a value for the given [key].
     */
    operator fun SharedPreferences.set(key: String, value: Any?)
        = when (value) {
            is String? -> edit { it.putString(key, value) }
            is Int -> edit { it.putInt(key, value) }
            is Boolean -> edit { it.putBoolean(key, value) }
            is Float -> edit { it.putFloat(key, value) }
            is Long -> edit { it.putLong(key, value) }
            else -> throw UnsupportedOperationException("Not yet implemented")
        }

    /**
     * finds a preference based on the given [key].
     * [T] is the type of value
     * @param defaultValue optional defaultValue - will take a default defaultValue if it is not specified
     */
    inline operator fun <reified T : Any> SharedPreferences.get(key: String, defaultValue: T? = null): T
        = when (T::class) {
            String::class -> getString(key, defaultValue as? String ?: "") as T
            Int::class -> getInt(key, defaultValue as? Int ?: -1) as T
            Boolean::class -> getBoolean(key, defaultValue as? Boolean ?: false) as T
            Float::class -> getFloat(key, defaultValue as? Float ?: -1f) as T
            Long::class -> getLong(key, defaultValue as? Long ?: -1) as T
            else -> throw UnsupportedOperationException("Not yet implemented")
        }
}

Very useful! Thank you!

Very elegant solution! I ended up combining it with this other solution for an even more accessible way of storing my app's SharedPreferences.

Great. @ivangarzab do you mind sharing your combined solution?

@JCarlosR I used it like below, to get the Prefs object globally:

Prefs.kt

object Prefs {

    private const val APP_PREFERENCES = "app_preferences"
    lateinit var preferences: SharedPreferences

    fun init(context: Context) {
        preferences = context.getSharedPreferences(APP_PREFERENCES, Context.MODE_PRIVATE)
    }

    private inline fun SharedPreferences.edit(operation: (SharedPreferences.Editor) -> Unit) {
        val editor = this.edit()
        operation(editor)
        editor.apply()
    }

    operator fun set(key: String, value: Any?) =
        when (value) {
            is String? -> preferences.edit { it.putString(key, value) }
            is Int -> preferences.edit { it.putInt(key, value) }
            is Boolean -> preferences.edit { it.putBoolean(key, value) }
            is Float -> preferences.edit { it.putFloat(key, value) }
            is Long -> preferences.edit { it.putLong(key, value) }
            else -> throw UnsupportedOperationException("Not yet implemented")
        }

    inline operator fun <reified T : Any> get(
        key: String,
        defaultValue: T? = null
    ): T =
        when (T::class) {
            String::class -> preferences.getString(key, defaultValue as String? ?: "") as T
            Int::class -> preferences.getInt(key, defaultValue as? Int ?: -1) as T
            Boolean::class -> preferences.getBoolean(key, defaultValue as? Boolean ?: false) as T
            Float::class -> preferences.getFloat(key, defaultValue as? Float ?: -1f) as T
            Long::class -> preferences.getLong(key, defaultValue as? Long ?: -1) as T
            else -> throw UnsupportedOperationException("Not yet implemented")
        }
}

App.kt

class App : Application() {
    override fun onCreate() {
        super.onCreate()
        Prefs.init(this)
    }
}