LiveData with shared preferences

Question

I have a settings screen where I am setting some values. When I set those values it gets saved in shared preferences and these values are needed in my request to the network api call as parameters.

Now I can use a listener for shared preferences in my activity then make an api call and get fresh data, but I want to use this with LiveData.

How can I listen for changes in the shared preferences using LiveData and then make the network call using the new parameters.

Answer 1

The following awesome piece of code is LiveData Implementation of SharedPreference. It works perfectly.

package com.chargingwatts.chargingalarm.util.preference;  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) }