moonlight200 · August 4, 2020 12:27
diff --git a/example.kt b/example.kt
 // 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.getBooleanLiveData("analytics_enabled", false).observe(this, { enabled ->
    if (enabled) {
      sendAnalytics()
    }
 })
diff --git a/SharedPreferenceLiveData.kt b/SharedPreferenceLiveData.kt
 import android.content.SharedPreferences
 import androidx.lifecycle.LiveData

 class SharedPreferenceLiveData<T>(
        private val sharedPrefs: SharedPreferences,
        val key: String,
        val defaultValue: T,
        private val valueExtractor: (sharedPrefs: SharedPreferences, prefKey: String, defValue: T) -> T
 ) : LiveData<T>() {
    private val preferenceChangeListener = SharedPreferences.OnSharedPreferenceChangeListener { sharedPrefs, key ->
        if (key == this.key) {
            postValue(valueExtractor(sharedPrefs, key, defaultValue))
        }
    }

    init {
        postValue(valueExtractor(sharedPrefs, key, defaultValue))
    }

    override fun onActive() {
        super.onActive()
        sharedPrefs.registerOnSharedPreferenceChangeListener(preferenceChangeListener)
    }

    override fun onInactive() {
        sharedPrefs.unregisterOnSharedPreferenceChangeListener(preferenceChangeListener)
        super.onInactive()
    }
 }

 fun SharedPreferences.getIntLiveData(key: String, defaultValue: Int = 0): LiveData<Int> =
        SharedPreferenceLiveData(this, key, defaultValue) { sharedPrefs, prefKey, defValue ->
            sharedPrefs.getInt(prefKey, defValue)
        }

 fun SharedPreferences.getStringLiveData(key: String, defaultValue: String = ""): LiveData<String> =
        SharedPreferenceLiveData(this, key, defaultValue) { sharedPrefs, prefKey, defValue ->
            sharedPrefs.getString(prefKey, defValue) ?: defValue
        }

 fun SharedPreferences.getBooleanLiveData(key: String, defaultValue: Boolean = false): LiveData<Boolean> =
        SharedPreferenceLiveData(this, key, defaultValue) { sharedPrefs, prefKey, defValue ->
            sharedPrefs.getBoolean(prefKey, defValue)
        }

 fun SharedPreferences.getFloatLiveData(key: String, defaultValue: Float = 0.0F): LiveData<Float> =
        SharedPreferenceLiveData(this, key, defaultValue) { sharedPrefs, prefKey, defValue ->
            sharedPrefs.getFloat(prefKey, defValue)
        }

 fun SharedPreferences.getLongLiveData(key: String, defaultValue: Long = 0L): LiveData<Long> =
        SharedPreferenceLiveData(this, key, defaultValue) { sharedPrefs, prefKey, defValue ->
            sharedPrefs.getLong(prefKey, defValue)
        }

 fun SharedPreferences.getStringSetLiveData(key: String, defaultValue: Set<String> = emptySet()): LiveData<Set<String>> =
        SharedPreferenceLiveData(this, key, defaultValue) { sharedPrefs, prefKey, defValue ->
            sharedPrefs.getStringSet(prefKey, defValue) ?: defValue
        }
	// 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.getBooleanLiveData("analytics_enabled", false).observe(this, { enabled ->
	if (enabled) {
	sendAnalytics()
	}
	})
	import android.content.SharedPreferences
	import androidx.lifecycle.LiveData

	class SharedPreferenceLiveData<T>(
	private val sharedPrefs: SharedPreferences,
	val key: String,
	val defaultValue: T,
	private val valueExtractor: (sharedPrefs: SharedPreferences, prefKey: String, defValue: T) -> T
	) : LiveData<T>() {
	private val preferenceChangeListener = SharedPreferences.OnSharedPreferenceChangeListener { sharedPrefs, key ->
	if (key == this.key) {
	postValue(valueExtractor(sharedPrefs, key, defaultValue))
	}
	}

	init {
	postValue(valueExtractor(sharedPrefs, key, defaultValue))
	}

	override fun onActive() {
	super.onActive()
	sharedPrefs.registerOnSharedPreferenceChangeListener(preferenceChangeListener)
	}

	override fun onInactive() {
	sharedPrefs.unregisterOnSharedPreferenceChangeListener(preferenceChangeListener)
	super.onInactive()
	}
	}

	fun SharedPreferences.getIntLiveData(key: String, defaultValue: Int = 0): LiveData<Int> =
	SharedPreferenceLiveData(this, key, defaultValue) { sharedPrefs, prefKey, defValue ->
	sharedPrefs.getInt(prefKey, defValue)
	}

	fun SharedPreferences.getStringLiveData(key: String, defaultValue: String = ""): LiveData<String> =
	SharedPreferenceLiveData(this, key, defaultValue) { sharedPrefs, prefKey, defValue ->
	sharedPrefs.getString(prefKey, defValue) ?: defValue
	}

	fun SharedPreferences.getBooleanLiveData(key: String, defaultValue: Boolean = false): LiveData<Boolean> =
	SharedPreferenceLiveData(this, key, defaultValue) { sharedPrefs, prefKey, defValue ->
	sharedPrefs.getBoolean(prefKey, defValue)
	}

	fun SharedPreferences.getFloatLiveData(key: String, defaultValue: Float = 0.0F): LiveData<Float> =
	SharedPreferenceLiveData(this, key, defaultValue) { sharedPrefs, prefKey, defValue ->
	sharedPrefs.getFloat(prefKey, defValue)
	}

	fun SharedPreferences.getLongLiveData(key: String, defaultValue: Long = 0L): LiveData<Long> =
	SharedPreferenceLiveData(this, key, defaultValue) { sharedPrefs, prefKey, defValue ->
	sharedPrefs.getLong(prefKey, defValue)
	}

	fun SharedPreferences.getStringSetLiveData(key: String, defaultValue: Set<String> = emptySet()): LiveData<Set<String>> =
	SharedPreferenceLiveData(this, key, defaultValue) { sharedPrefs, prefKey, defValue ->
	sharedPrefs.getStringSet(prefKey, defValue) ?: defValue
	}