Instantly share code, notes, and snippets.
Last active
September 25, 2018 10:17
-
Star
(0)
0
You must be signed in to star a gist -
Fork
(0)
0
You must be signed in to fork a gist
-
Save SpaceBison/a318ec21e319f7ac20e37bb29d92509d to your computer and use it in GitHub Desktop.
Android Kotlin - SharedPreferences property delegates
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
import android.content.SharedPreferences | |
import kotlin.properties.ReadWriteProperty | |
import kotlin.reflect.KFunction3 | |
import kotlin.reflect.KProperty | |
@Suppress("UNCHECKED_CAST") | |
inline fun <reified T> sharedPreferences(sharedPreferences: SharedPreferences, key: String): SharedPreferencesNullableProperty<T> = | |
when (T::class) { | |
Boolean::class -> SharedPreferencesNullableProperty(sharedPreferences, key, false, | |
SharedPreferences::getBoolean, SharedPreferences.Editor::putBoolean) | |
Float::class -> SharedPreferencesNullableProperty(sharedPreferences, key, 0f, | |
SharedPreferences::getFloat, SharedPreferences.Editor::putFloat) | |
Int::class -> SharedPreferencesNullableProperty(sharedPreferences, key, 0, | |
SharedPreferences::getInt, SharedPreferences.Editor::putInt) | |
Long::class -> SharedPreferencesNullableProperty(sharedPreferences, key, 0L, | |
SharedPreferences::getLong, SharedPreferences.Editor::putLong) | |
String::class -> SharedPreferencesNullableProperty(sharedPreferences, key, null, | |
SharedPreferences::getString, SharedPreferences.Editor::putString) | |
Set::class -> SharedPreferencesNullableProperty(sharedPreferences, key, null, | |
SharedPreferences::getStringSet, SharedPreferences.Editor::putStringSet) | |
else -> throw IllegalStateException("Illegal property type: ${T::class}") | |
} as SharedPreferencesNullableProperty<T> | |
class SharedPreferencesNullableProperty<T>( | |
private val sharedPreferences: SharedPreferences, | |
val key: String, | |
val defaultValue: T, | |
val getValue: KFunction3<SharedPreferences, String, T, T>, | |
val setValue: KFunction3<SharedPreferences.Editor, String, T, SharedPreferences.Editor>) | |
: ReadWriteProperty<Any, T?> { | |
override fun getValue(thisRef: Any, property: KProperty<*>): T? = | |
if (!sharedPreferences.contains(key)) { | |
null | |
} else { | |
getValue(sharedPreferences, key, defaultValue) | |
} | |
override fun setValue(thisRef: Any, property: KProperty<*>, value: T?) = | |
sharedPreferences.edit().apply { | |
if (value == null) { | |
remove(key) | |
} else { | |
setValue(sharedPreferences.edit(), key, value).apply() | |
} | |
}.apply() | |
} |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
import android.content.SharedPreferences | |
import kotlin.properties.ReadWriteProperty | |
import kotlin.reflect.KFunction3 | |
import kotlin.reflect.KProperty | |
@Suppress("UNCHECKED_CAST") | |
fun <T> sharedPreferences(sharedPreferences: SharedPreferences, key: String, defaultValue: T): SharedPreferencesProperty<T> = | |
when (defaultValue) { | |
is Boolean -> SharedPreferencesProperty(sharedPreferences, key, defaultValue, | |
SharedPreferences::getBoolean, SharedPreferences.Editor::putBoolean) | |
is Float -> SharedPreferencesProperty(sharedPreferences, key, defaultValue, | |
SharedPreferences::getFloat, SharedPreferences.Editor::putFloat) | |
is Int -> SharedPreferencesProperty(sharedPreferences, key, defaultValue, | |
SharedPreferences::getInt, SharedPreferences.Editor::putInt) | |
is Long -> SharedPreferencesProperty(sharedPreferences, key, defaultValue, | |
SharedPreferences::getLong, SharedPreferences.Editor::putLong) | |
is String -> SharedPreferencesProperty(sharedPreferences, key, defaultValue, | |
SharedPreferences::getString, SharedPreferences.Editor::putString) | |
is Set<*> -> SharedPreferencesProperty(sharedPreferences, key, defaultValue as Set<String>, | |
SharedPreferences::getStringSet, SharedPreferences.Editor::putStringSet) | |
else -> throw IllegalStateException("Illegal property type: ${(defaultValue as Any).javaClass}") | |
} as SharedPreferencesProperty<T> | |
open class SharedPreferencesProperty<T>( | |
private val sharedPreferences: SharedPreferences, | |
val key: String, | |
val defaultValue: T, | |
val getValue: KFunction3<SharedPreferences, String, T, T>, | |
val setValue: KFunction3<SharedPreferences.Editor, String, T, SharedPreferences.Editor>) | |
: ReadWriteProperty<Any, T> { | |
override fun getValue(thisRef: Any, property: KProperty<*>): T = | |
getValue(sharedPreferences, key, defaultValue) | |
override fun setValue(thisRef: Any, property: KProperty<*>, value: T) = | |
setValue(sharedPreferences.edit(), key, value).apply() | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment