Skip to content

Instantly share code, notes, and snippets.

Show Gist options
  • Save kenchoong/968c32b9bed447fc34ac048742a632d9 to your computer and use it in GitHub Desktop.
Save kenchoong/968c32b9bed447fc34ac048742a632d9 to your computer and use it in GitHub Desktop.
Creates LiveData objects that observe a value in SharedPreferences while they have active listeners.
// 1. Get a reference to SharedPreferences however you normally would.
val prefs: SharedPreferences
// 2. Use the extension functions to create a LiveData object of whatever type you need and observe the result.
prefs.booleanLiveData("analytics_enabled", false).observe(this, { enabled ->
if (enabled != null && enabled) {
sendAnalytics()
}
})
import android.arch.lifecycle.LiveData
import android.content.SharedPreferences
abstract class SharedPreferenceLiveData<T>(val sharedPrefs: SharedPreferences,
val key: String,
val defValue: T) : LiveData<T>() {
private val preferenceChangeListener = SharedPreferences.OnSharedPreferenceChangeListener { sharedPreferences, key ->
if (key == this.key) {
value = getValueFromPreferences(key, defValue)
}
}
abstract fun getValueFromPreferences(key: String, defValue: T): T
override fun onActive() {
super.onActive()
value = getValueFromPreferences(key, defValue)
sharedPrefs.registerOnSharedPreferenceChangeListener(preferenceChangeListener)
}
override fun onInactive() {
sharedPrefs.unregisterOnSharedPreferenceChangeListener(preferenceChangeListener)
super.onInactive()
}
}
class SharedPreferenceIntLiveData(sharedPrefs: SharedPreferences, key: String, defValue: Int) :
SharedPreferenceLiveData<Int>(sharedPrefs, key, defValue) {
override fun getValueFromPreferences(key: String, defValue: Int): Int = sharedPrefs.getInt(key, defValue)
}
class SharedPreferenceStringLiveData(sharedPrefs: SharedPreferences, key: String, defValue: String) :
SharedPreferenceLiveData<String>(sharedPrefs, key, defValue) {
override fun getValueFromPreferences(key: String, defValue: String): String = sharedPrefs.getString(key, defValue)
}
class SharedPreferenceBooleanLiveData(sharedPrefs: SharedPreferences, key: String, defValue: Boolean) :
SharedPreferenceLiveData<Boolean>(sharedPrefs, key, defValue) {
override fun getValueFromPreferences(key: String, defValue: Boolean): Boolean = sharedPrefs.getBoolean(key, defValue)
}
class SharedPreferenceFloatLiveData(sharedPrefs: SharedPreferences, key: String, defValue: Float) :
SharedPreferenceLiveData<Float>(sharedPrefs, key, defValue) {
override fun getValueFromPreferences(key: String, defValue: Float): Float = sharedPrefs.getFloat(key, defValue)
}
class SharedPreferenceLongLiveData(sharedPrefs: SharedPreferences, key: String, defValue: Long) :
SharedPreferenceLiveData<Long>(sharedPrefs, key, defValue) {
override fun getValueFromPreferences(key: String, defValue: Long): Long = sharedPrefs.getLong(key, defValue)
}
class SharedPreferenceStringSetLiveData(sharedPrefs: SharedPreferences, key: String, defValue: Set<String>) :
SharedPreferenceLiveData<Set<String>>(sharedPrefs, key, defValue) {
override fun getValueFromPreferences(key: String, defValue: Set<String>): Set<String> = sharedPrefs.getStringSet(key, defValue)
}
fun SharedPreferences.intLiveData(key: String, defValue: Int): SharedPreferenceLiveData<Int> {
return SharedPreferenceIntLiveData(this, key, defValue)
}
fun SharedPreferences.stringLiveData(key: String, defValue: String): SharedPreferenceLiveData<String> {
return SharedPreferenceStringLiveData(this, key, defValue)
}
fun SharedPreferences.booleanLiveData(key: String, defValue: Boolean): SharedPreferenceLiveData<Boolean> {
return SharedPreferenceBooleanLiveData(this, key, defValue)
}
fun SharedPreferences.floatLiveData(key: String, defValue: Float): SharedPreferenceLiveData<Float> {
return SharedPreferenceFloatLiveData(this, key, defValue)
}
fun SharedPreferences.longLiveData(key: String, defValue: Long): SharedPreferenceLiveData<Long> {
return SharedPreferenceLongLiveData(this, key, defValue)
}
fun SharedPreferences.stringSetLiveData(key: String, defValue: Set<String>): SharedPreferenceLiveData<Set<String>> {
return SharedPreferenceStringSetLiveData(this, key, defValue)
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment