Android SharedPreferences Rx extension

SharedPreferences+Rx.kt

import android.content.SharedPreferences
import io.reactivex.Maybe
import io.reactivex.Single

@androidx.annotation.CheckResult
fun SharedPreferences.boolean(key: String, defValue: Boolean): Single<Boolean> = Single.just(getBoolean(key, defValue))

@androidx.annotation.CheckResult
fun SharedPreferences.boolean(key: String): Maybe<Boolean> = Maybe.create { maybeEmitter ->
    if (contains(key)) {
        maybeEmitter.onSuccess(getBoolean(key, false))
    }
    maybeEmitter.onComplete()
}

@androidx.annotation.CheckResult
fun SharedPreferences.float(key: String, defValue: Float): Single<Float> = Single.just(getFloat(key, defValue))

@androidx.annotation.CheckResult
fun SharedPreferences.float(key: String): Maybe<Float> = Maybe.create { maybeEmitter ->
    if (contains(key)) {
        maybeEmitter.onSuccess(getFloat(key, -1f))
    }
    maybeEmitter.onComplete()
}

@androidx.annotation.CheckResult
fun SharedPreferences.int(key: String, defValue: Int): Single<Int> = Single.just(getInt(key, defValue))

@androidx.annotation.CheckResult
fun SharedPreferences.int(key: String): Maybe<Int> = Maybe.create { maybeEmitter ->
    if (contains(key)) {
        maybeEmitter.onSuccess(getInt(key, -1))
    }
    maybeEmitter.onComplete()
}

@androidx.annotation.CheckResult
fun SharedPreferences.long(key: String, defValue: Long): Single<Long> = Single.just(getLong(key, defValue))

@androidx.annotation.CheckResult
fun SharedPreferences.long(key: String): Maybe<Long> = Maybe.create { maybeEmitter ->
    if (contains(key)) {
        maybeEmitter.onSuccess(getLong(key, -1L))
    }
    maybeEmitter.onComplete()
}

@androidx.annotation.CheckResult
fun SharedPreferences.string(key: String, defValue: String): Single<String> = Single.just(getString(key, defValue))

@androidx.annotation.CheckResult
fun SharedPreferences.stringSet(key: String, defValue: Set<String>): Single<Set<String>> = Single.just(getStringSet(key, defValue))

@androidx.annotation.CheckResult
fun SharedPreferences.string(key: String): Maybe<String> = Maybe.create { maybeEmitter ->
    getString(key, null)?.let {
        maybeEmitter.onSuccess(it)
    }
    maybeEmitter.onComplete()
}

@androidx.annotation.CheckResult
fun SharedPreferences.stringSet(key: String): Maybe<Set<String>> = Maybe.create { maybeEmitter ->
    getStringSet(key, null)?.let {
        maybeEmitter.onSuccess(it)
    }
    maybeEmitter.onComplete()
}