SharedPreferences Delegates

SharedPreferencesDelegates.kt

import android.content.SharedPreferences
import kotlin.properties.ReadWriteProperty
import kotlin.reflect.KProperty

fun SharedPreferences.boolean(defaultValue: Boolean, key: String = ""): SharedPreferencesBooleanDelegate {
    return SharedPreferencesBooleanDelegate(this, key, defaultValue)
}

fun SharedPreferences.float(defaultValue: Float, key: String = ""): SharedPreferencesFloatDelegate {
    return SharedPreferencesFloatDelegate(this, key, defaultValue)
}

fun SharedPreferences.int(defaultValue: Int, key: String = ""): SharedPreferencesIntDelegate {
    return SharedPreferencesIntDelegate(this, key, defaultValue)
}

fun SharedPreferences.long(defaultValue: Long, key: String = ""): SharedPreferencesLongDelegate {
    return SharedPreferencesLongDelegate(this, key, defaultValue)
}

fun SharedPreferences.string(defaultValue: String, key: String = ""): SharedPreferencesStringDelegate {
    return SharedPreferencesStringDelegate(this, key, defaultValue)
}

fun SharedPreferences.stringSet(defaultValue: Set<String>, key: String = ""): SharedPreferencesStringSetDelegate {
    return SharedPreferencesStringSetDelegate(this, key, defaultValue)
}

//region Delegates

sealed class SharedPreferencesDelegate<T>(private val key: String) : ReadWriteProperty<Any, T> {
    protected fun getKey(property: KProperty<*>): String {
        return if (key.isEmpty()) property.name else key
    }
}

class SharedPreferencesBooleanDelegate(
        private val preferences: SharedPreferences,
        key: String,
        private val defaultValue: Boolean) : SharedPreferencesDelegate<Boolean>(key) {

    override operator fun getValue(thisRef: Any, property: KProperty<*>): Boolean {
        return preferences.getBoolean(getKey(property), defaultValue)
    }

    override operator fun setValue(thisRef: Any, property: KProperty<*>, value: Boolean) {
        preferences.edit().putBoolean(getKey(property), value).apply()
    }
}

class SharedPreferencesFloatDelegate(
        private val preferences: SharedPreferences,
        key: String,
        private val defaultValue: Float) : SharedPreferencesDelegate<Float>(key) {

    override operator fun getValue(thisRef: Any, property: KProperty<*>): Float {
        return preferences.getFloat(getKey(property), defaultValue)
    }

    override operator fun setValue(thisRef: Any, property: KProperty<*>, value: Float) {
        preferences.edit().putFloat(getKey(property), value).apply()
    }
}

class SharedPreferencesIntDelegate(
        private val preferences: SharedPreferences,
        key: String,
        private val defaultValue: Int) : SharedPreferencesDelegate<Int>(key) {

    override operator fun getValue(thisRef: Any, property: KProperty<*>): Int {
        return preferences.getInt(getKey(property), defaultValue)
    }

    override operator fun setValue(thisRef: Any, property: KProperty<*>, value: Int) {
        preferences.edit().putInt(getKey(property), value).apply()
    }
}

class SharedPreferencesLongDelegate(
        private val preferences: SharedPreferences,
        key: String,
        private val defaultValue: Long) : SharedPreferencesDelegate<Long>(key) {

    override operator fun getValue(thisRef: Any, property: KProperty<*>): Long {
        return preferences.getLong(getKey(property), defaultValue)
    }

    override operator fun setValue(thisRef: Any, property: KProperty<*>, value: Long) {
        preferences.edit().putLong(getKey(property), value).apply()
    }
}

class SharedPreferencesStringDelegate(
        private val preferences: SharedPreferences,
        key: String,
        private val defaultValue: String) : SharedPreferencesDelegate<String>(key) {

    override operator fun getValue(thisRef: Any, property: KProperty<*>): String {
        return preferences.getString(getKey(property), defaultValue) ?: defaultValue
    }

    override operator fun setValue(thisRef: Any, property: KProperty<*>, value: String) {
        preferences.edit().putString(getKey(property), value).apply()
    }
}

class SharedPreferencesStringSetDelegate(
        private val preferences: SharedPreferences,
        key: String,
        private val defaultValue: Set<String>) : SharedPreferencesDelegate<Set<String>>(key) {

    override operator fun getValue(thisRef: Any, property: KProperty<*>): Set<String> {
        return preferences.getStringSet(getKey(property), defaultValue) ?: defaultValue
    }

    override operator fun setValue(thisRef: Any, property: KProperty<*>, value: Set<String>) {
        preferences.edit().putStringSet(getKey(property), value).apply()
    }
}

//endregion