Kotlin Extensions - Android SharedPreferences

SharedPreferencesExtensions.kt

import android.content.SharedPreferences
import android.text.TextUtils
import java.security.spec.InvalidParameterSpecException

/**
 * Return value on the given key.
 * [T] is the type of value
 * @param defaultValue optional default value
 */
inline operator fun <reified T : Any> SharedPreferences.get(key: String, defaultValue: T? = null): T {
    return 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")
    }
}

/**
 * Puts a key value pair in SharedPreferences if doesn't exists, otherwise updates value on given [key]
 */
@Suppress("UNCHECKED_CAST")
inline operator fun <reified T> SharedPreferences.set(key: String, value: T) {
    if (TextUtils.isEmpty(key)) {
        throw InvalidParameterSpecException("Invalid key")
    }

    val editor = this.edit()
    when (value) {
        is Boolean -> editor.putBoolean(key, value as Boolean)
        is Float -> editor.putFloat(key, value as Float)
        is Int -> editor.putInt(key, value as Int)
        is Long -> editor.putLong(key, value as Long)
        is String -> editor.putString(key, value as String)
        is Set<*> -> editor.putStringSet(key, value as Set<String>)
        else -> throw UnsupportedOperationException("Not yet implemented")
    }
    editor.apply()
}

SharedPreferencesExtensionsExample.kt

import *.utils.extensions.get
import *.utils.extensions.set
import android.content.SharedPreferences

class SharedPreferencesExtensionsExample(private val sharedPreferences: SharedPreferences) {

    fun shouldShowDialog(): Boolean {
        return sharedPreferences["dialog_key", true]
    }

    fun setShouldShowDialog(shouldShowDialog: Boolean) {
        sharedPreferences["dialog_key"] = shouldShowDialog
    }
}