Release 0.1.7

- load more pages of GE results
- If server-side clustering is not available, apply local Clustering

app/build.gradle

@@ -13,8 +13,8 @@ android {
         applicationId "net.vonforst.evmap"
         minSdkVersion 21
         targetSdkVersion 29
-        versionCode 13
-        versionName "0.1.5"
+        versionCode 15
+        versionName "0.1.7"
 
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
@@ -87,11 +87,7 @@ dependencies {
     implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
     implementation 'androidx.recyclerview:recyclerview:1.1.0'
     implementation 'androidx.browser:browser:1.2.0'
-    implementation 'com.google.maps.android:android-maps-utils:0.5'
     implementation 'com.github.johan12345:CustomBottomSheetBehavior:f69f532660'
-    implementation 'com.google.android.gms:play-services-maps:17.0.0'
-    implementation 'com.google.android.gms:play-services-location:17.0.0'
-    implementation 'com.google.android.libraries.places:places:2.3.0'
     implementation 'com.squareup.retrofit2:retrofit:2.7.2'
     implementation 'com.squareup.retrofit2:converter-moshi:2.7.2'
     implementation 'com.squareup.moshi:moshi-kotlin:1.9.2'
@@ -102,6 +98,15 @@ dependencies {
     implementation 'com.airbnb.android:lottie:3.4.0'
     implementation 'io.michaelrocks:bimap:1.0.2'
 
+    // Google Maps v3 Beta
+    implementation name:'maps-sdk-3.0.0-beta', ext:'aar'
+    implementation name:'places-maps-sdk-3.0.0-beta', ext:'aar'
+    implementation 'com.google.maps.android:android-maps-utils-v3:1.3.3'
+    implementation 'com.google.android.gms:play-services-basement:17.3.0'
+    implementation 'com.google.android.gms:play-services-base:17.3.0'
+    implementation 'com.google.android.gms:play-services-gcm:17.0.0'
+    implementation 'com.google.android.gms:play-services-location:17.0.0'
+
     // navigation library
     def nav_version = "2.3.0-beta01"
     implementation "androidx.navigation:navigation-fragment-ktx:$nav_version"

app/src/main/java/net/vonforst/evmap/MapsActivity.kt

@@ -1,5 +1,6 @@
 package net.vonforst.evmap
 
+import android.content.Context
 import android.content.Intent
 import android.net.Uri
 import android.os.Bundle
@@ -19,6 +20,7 @@ import com.google.android.material.navigation.NavigationView
 import com.google.android.material.snackbar.Snackbar
 import net.vonforst.evmap.api.goingelectric.ChargeLocation
 import net.vonforst.evmap.storage.PreferenceDataSource
+import net.vonforst.evmap.utils.LocaleContextWrapper
 
 
 const val REQUEST_LOCATION_PERMISSION = 1
@@ -34,6 +36,14 @@ class MapsActivity : AppCompatActivity() {
     var fragmentCallback: FragmentCallback? = null
     private lateinit var prefs: PreferenceDataSource
 
+    override fun attachBaseContext(newBase: Context) {
+        return super.attachBaseContext(
+            LocaleContextWrapper.wrap(
+                newBase, PreferenceDataSource(newBase).language
+            )
+        );
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 

app/src/main/java/net/vonforst/evmap/api/goingelectric/GoingElectricApi.kt

@@ -3,6 +3,7 @@ package net.vonforst.evmap.api.goingelectric
 import android.content.Context
 import com.facebook.stetho.okhttp3.StethoInterceptor
 import com.squareup.moshi.Moshi
+import net.vonforst.evmap.BuildConfig
 import okhttp3.Cache
 import okhttp3.OkHttpClient
 import retrofit2.Call
@@ -25,7 +26,8 @@ interface GoingElectricApi {
         @Query("min_power") minPower: Int,
         @Query("plugs") plugs: String?,
         @Query("chargecards") chargecards: String?,
-        @Query("networks") networks: String?
+        @Query("networks") networks: String?,
+        @Query("startkey") startkey: Int?
     ): Response<ChargepointList>
 
     @GET("chargepoints/")
@@ -56,7 +58,9 @@ interface GoingElectricApi {
                     original = original.newBuilder().url(url).build()
                     chain.proceed(original)
                 }
-                addNetworkInterceptor(StethoInterceptor())
+                if (BuildConfig.DEBUG) {
+                    addNetworkInterceptor(StethoInterceptor())
+                }
                 if (context != null) {
                     cache(Cache(context.getCacheDir(), cacheSize))
                 }

app/src/main/java/net/vonforst/evmap/api/goingelectric/GoingElectricModel.kt

@@ -24,7 +24,8 @@ import kotlin.math.floor
 @JsonClass(generateAdapter = true)
 data class ChargepointList(
     val status: String,
-    val chargelocations: List<ChargepointListItem>
+    val chargelocations: List<ChargepointListItem>,
+    @JsonObjectOrFalse val startkey: Int?
 )
 
 @JsonClass(generateAdapter = true)
@@ -277,4 +278,4 @@ data class ChargeCard(
     @Json(name = "card_id") @PrimaryKey val id: Long,
     val name: String,
     val url: String
-)
+)

app/src/main/java/net/vonforst/evmap/fragment/FavoritesFragment.kt

@@ -18,7 +18,7 @@ import androidx.recyclerview.widget.DividerItemDecoration
 import androidx.recyclerview.widget.LinearLayoutManager
 import com.google.android.gms.location.FusedLocationProviderClient
 import com.google.android.gms.location.LocationServices
-import com.google.android.gms.maps.model.LatLng
+import com.google.android.libraries.maps.model.LatLng
 import net.vonforst.evmap.MapsActivity
 import net.vonforst.evmap.R
 import net.vonforst.evmap.adapter.FavoritesAdapter

app/src/main/java/net/vonforst/evmap/fragment/MapFragment.kt

@@ -34,11 +34,11 @@ import androidx.transition.TransitionInflater
 import androidx.transition.TransitionManager
 import com.google.android.gms.location.FusedLocationProviderClient
 import com.google.android.gms.location.LocationServices
-import com.google.android.gms.maps.CameraUpdateFactory
-import com.google.android.gms.maps.GoogleMap
-import com.google.android.gms.maps.OnMapReadyCallback
-import com.google.android.gms.maps.SupportMapFragment
-import com.google.android.gms.maps.model.*
+import com.google.android.libraries.maps.CameraUpdateFactory
+import com.google.android.libraries.maps.GoogleMap
+import com.google.android.libraries.maps.OnMapReadyCallback
+import com.google.android.libraries.maps.SupportMapFragment
+import com.google.android.libraries.maps.model.*
 import com.google.android.libraries.places.api.model.Place
 import com.google.android.libraries.places.widget.Autocomplete
 import com.google.android.libraries.places.widget.model.AutocompleteActivityMode
@@ -89,6 +89,7 @@ class MapFragment : Fragment(), OnMapReadyCallback, MapsActivity.FragmentCallbac
     private var markers: MutableBiMap<Marker, ChargeLocation> = HashBiMap()
     private var clusterMarkers: List<Marker> = emptyList()
     private var searchResultMarker: Marker? = null
+    private var connectionErrorSnackbar: Snackbar? = null
 
     private lateinit var clusterIconGenerator: ClusterIconGenerator
     private lateinit var chargerIconGenerator: ChargerIconGenerator
@@ -312,9 +313,31 @@ class MapFragment : Fragment(), OnMapReadyCallback, MapsActivity.FragmentCallbac
                 unhighlightAllMarkers()
             }
         })
-        vm.chargepoints.observe(viewLifecycleOwner, Observer {
-            val chargepoints = it.data
-            if (chargepoints != null) updateMap(chargepoints)
+        vm.chargepoints.observe(viewLifecycleOwner, Observer { res ->
+            when (res.status) {
+                Status.ERROR -> {
+                    val view = view ?: return@Observer
+
+                    connectionErrorSnackbar?.dismiss()
+                    connectionErrorSnackbar = Snackbar
+                        .make(view, R.string.connection_error, Snackbar.LENGTH_INDEFINITE)
+                        .setAction(R.string.retry) {
+                            connectionErrorSnackbar?.dismiss()
+                            vm.reloadChargepoints()
+                        }
+                    connectionErrorSnackbar!!.show()
+                }
+                Status.SUCCESS -> {
+                    connectionErrorSnackbar?.dismiss()
+                }
+                Status.LOADING -> {
+                }
+            }
+
+            val chargepoints = res.data
+            if (chargepoints != null) {
+                updateMap(chargepoints)
+            }
         })
         vm.favorites.observe(viewLifecycleOwner, Observer {
             updateFavoriteToggle()
@@ -347,11 +370,14 @@ class MapFragment : Fragment(), OnMapReadyCallback, MapsActivity.FragmentCallbac
         vm.mapTrafficEnabled.observe(viewLifecycleOwner, Observer {
             map?.isTrafficEnabled = it
         })
+
+        updateBackPressedCallback()
     }
 
     private fun updateBackPressedCallback() {
         backPressedCallback.isEnabled =
-            vm.bottomSheetState.value != STATE_HIDDEN || vm.searchResult.value != null
+            vm.bottomSheetState.value != null && vm.bottomSheetState.value != STATE_HIDDEN
+                    || vm.searchResult.value != null
                     || (vm.layersMenuOpen.value ?: false)
     }
 

app/src/main/java/net/vonforst/evmap/fragment/SettingsFragment.kt

@@ -1,5 +1,6 @@
 package net.vonforst.evmap.fragment
 
+import android.content.SharedPreferences
 import android.os.Bundle
 import android.view.View
 import androidx.appcompat.widget.Toolbar
@@ -11,7 +12,8 @@ import net.vonforst.evmap.MapsActivity
 import net.vonforst.evmap.R
 
 
-class SettingsFragment : PreferenceFragmentCompat() {
+class SettingsFragment : PreferenceFragmentCompat(),
+    SharedPreferences.OnSharedPreferenceChangeListener {
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
         val toolbar = view.findViewById(R.id.toolbar) as Toolbar
@@ -33,4 +35,26 @@ class SettingsFragment : PreferenceFragmentCompat() {
         }
     }
 
+    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences, key: String) {
+        when (key) {
+            "language" -> {
+                activity?.let {
+                    it.finish();
+                    it.startActivity(it.intent);
+                }
+            }
+        }
+    }
+
+    override fun onResume() {
+        super.onResume()
+        preferenceManager.sharedPreferences.registerOnSharedPreferenceChangeListener(this)
+    }
+
+    override fun onPause() {
+        preferenceManager.sharedPreferences
+            .unregisterOnSharedPreferenceChangeListener(this)
+        super.onPause()
+    }
+
 }

app/src/main/java/net/vonforst/evmap/storage/PreferenceDataSource.kt

@@ -30,4 +30,7 @@ class PreferenceDataSource(context: Context) {
         set(value) {
             sp.edit().putLong("last_chargecard_update", value.toEpochMilli()).apply()
         }
+
+    val language: String
+        get() = sp.getString("language", "default")!!
 }

app/src/main/java/net/vonforst/evmap/ui/Clustering.kt

@@ -0,0 +1,41 @@
+package net.vonforst.evmap.ui;
+
+import com.google.android.libraries.maps.model.LatLng
+import com.google.maps.android.clustering.ClusterItem
+import com.google.maps.android.clustering.algo.NonHierarchicalDistanceBasedAlgorithm
+import net.vonforst.evmap.api.goingelectric.ChargeLocation
+import net.vonforst.evmap.api.goingelectric.ChargeLocationCluster
+import net.vonforst.evmap.api.goingelectric.ChargepointListItem
+import net.vonforst.evmap.api.goingelectric.Coordinate
+
+
+fun cluster(
+    result: List<ChargepointListItem>,
+    zoom: Float,
+    clusterDistance: Int
+): List<ChargepointListItem> {
+    val clusters = result.filterIsInstance<ChargeLocationCluster>()
+    val locations = result.filterIsInstance<ChargeLocation>()
+
+    val clusterItems = locations.map { ChargepointClusterItem(it) }
+
+    val algo = NonHierarchicalDistanceBasedAlgorithm<ChargepointClusterItem>()
+    algo.maxDistanceBetweenClusteredItems = clusterDistance
+    algo.addItems(clusterItems)
+    return algo.getClusters(zoom).map {
+        if (it.size == 1) {
+            it.items.first().charger
+        } else {
+            ChargeLocationCluster(it.size, Coordinate(it.position.latitude, it.position.longitude))
+        }
+    } + clusters
+}
+
+private class ChargepointClusterItem(val charger: ChargeLocation) : ClusterItem {
+    override fun getSnippet(): String? = null
+
+    override fun getTitle(): String? = charger.name
+
+    override fun getPosition(): LatLng = LatLng(charger.coordinates.lat, charger.coordinates.lng)
+
+}

app/src/main/java/net/vonforst/evmap/ui/IconGenerators.kt

@@ -11,8 +11,8 @@ import androidx.annotation.ColorRes
 import androidx.core.content.ContextCompat
 import androidx.core.graphics.drawable.DrawableCompat
 import androidx.core.widget.TextViewCompat
-import com.google.android.gms.maps.model.BitmapDescriptor
-import com.google.android.gms.maps.model.BitmapDescriptorFactory
+import com.google.android.libraries.maps.model.BitmapDescriptor
+import com.google.android.libraries.maps.model.BitmapDescriptorFactory
 import com.google.maps.android.ui.IconGenerator
 import com.google.maps.android.ui.SquareTextView
 import net.vonforst.evmap.R

app/src/main/java/net/vonforst/evmap/ui/MarkerUtils.kt

@@ -5,7 +5,7 @@ import android.view.animation.BounceInterpolator
 import androidx.core.animation.addListener
 import androidx.interpolator.view.animation.FastOutLinearInInterpolator
 import androidx.interpolator.view.animation.LinearOutSlowInInterpolator
-import com.google.android.gms.maps.model.Marker
+import com.google.android.libraries.maps.model.Marker
 import net.vonforst.evmap.R
 import net.vonforst.evmap.api.goingelectric.ChargeLocation
 import kotlin.math.max

app/src/main/java/net/vonforst/evmap/utils/LocaleContextWrapper.kt

@@ -0,0 +1,42 @@
+package net.vonforst.evmap.utils
+
+import android.annotation.TargetApi
+import android.content.Context
+import android.content.ContextWrapper
+import android.content.res.Configuration
+import android.os.Build
+import java.util.*
+
+
+class LocaleContextWrapper(base: Context?) : ContextWrapper(base) {
+    companion object {
+        fun wrap(context: Context, language: String): ContextWrapper {
+            val config: Configuration = context.resources.configuration
+            var sysLocale: Locale? = null
+            sysLocale = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
+                config.locales.get(0)
+            } else {
+                @Suppress("DEPRECATION")
+                config.locale
+            }
+            var ctx = context
+            if (language != "" && language != "default" && sysLocale.language != language) {
+                val locale = Locale(language)
+                Locale.setDefault(locale)
+                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
+                    config.setLocale(locale)
+                } else {
+                    @Suppress("DEPRECATION")
+                    config.locale = locale
+                }
+                ctx = context.createConfigurationContext(config)
+            }
+            return LocaleContextWrapper(ctx)
+        }
+
+        @TargetApi(Build.VERSION_CODES.N)
+        fun setSystemLocale(config: Configuration, locale: Locale?) {
+            config.setLocale(locale)
+        }
+    }
+}

app/src/main/java/net/vonforst/evmap/viewmodel/FavoritesViewModel.kt

@@ -2,7 +2,7 @@ package net.vonforst.evmap.viewmodel
 
 import android.app.Application
 import androidx.lifecycle.*
-import com.google.android.gms.maps.model.LatLng
+import com.google.android.libraries.maps.model.LatLng
 import kotlinx.coroutines.async
 import kotlinx.coroutines.awaitAll
 import kotlinx.coroutines.launch

app/src/main/java/net/vonforst/evmap/viewmodel/FilterViewModel.kt

@@ -61,7 +61,7 @@ private fun MediatorLiveData<List<Filter<FilterValue>>>.buildFilters(
         plug.name to (plugNames[plug.name] ?: plug.name)
     }?.toMap() ?: return
     val networkMap = networks.value?.map { it.name to it.name }?.toMap() ?: return
-    val chargecardMap = chargeCards.value?.map { it.name to it.name }?.toMap() ?: return
+    val chargecardMap = chargeCards.value?.map { it.id.toString() to it.name }?.toMap() ?: return
     value = listOf(
         BooleanFilter(application.getString(R.string.filter_free), "freecharging"),
         BooleanFilter(application.getString(R.string.filter_free_parking), "freeparking"),

app/src/main/java/net/vonforst/evmap/viewmodel/MapViewModel.kt

@@ -2,18 +2,21 @@ package net.vonforst.evmap.viewmodel
 
 import android.app.Application
 import androidx.lifecycle.*
-import com.google.android.gms.maps.GoogleMap
-import com.google.android.gms.maps.model.LatLngBounds
+import com.google.android.libraries.maps.GoogleMap
+import com.google.android.libraries.maps.model.LatLngBounds
 import com.google.android.libraries.places.api.model.Place
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
 import net.vonforst.evmap.api.availability.ChargeLocationStatus
 import net.vonforst.evmap.api.availability.getAvailability
 import net.vonforst.evmap.api.goingelectric.*
 import net.vonforst.evmap.storage.*
+import net.vonforst.evmap.ui.cluster
 import retrofit2.Call
 import retrofit2.Callback
 import retrofit2.Response
+import java.io.IOException
 
 data class MapPosition(val bounds: LatLngBounds, val zoom: Float)
 
@@ -74,9 +77,7 @@ class MapViewModel(application: Application, geApiKey: String) : AndroidViewMode
                 value = Resource.loading(emptyList())
                 listOf(mapPosition, filtersWithValue).forEach {
                     addSource(it) {
-                        val pos = mapPosition.value ?: return@addSource
-                        val filters = filtersWithValue.value ?: return@addSource
-                        loadChargepoints(pos, filters)
+                        reloadChargepoints()
                     }
                 }
             }
@@ -172,6 +173,12 @@ class MapViewModel(application: Application, geApiKey: String) : AndroidViewMode
         }
     }
 
+    fun reloadChargepoints() {
+        val pos = mapPosition.value ?: return
+        val filters = filtersWithValue.value ?: return
+        loadChargepoints(pos, filters)
+    }
+
     private fun loadChargepoints(
         mapPosition: MapPosition,
         filters: List<FilterWithValue<out FilterValue>>
@@ -218,35 +225,63 @@ class MapViewModel(application: Application, geApiKey: String) : AndroidViewMode
         val networks = formatMultipleChoice(networksVal)
 
         // do not use clustering if filters need to be applied locally.
-        val useClustering = minConnectors <= 1 && zoom < 13
+        val useClustering = zoom < 13
+        val geClusteringAvailable = minConnectors <= 1
+        val useGeClustering = useClustering && geClusteringAvailable
         val clusterDistance = if (useClustering) getClusterDistance(zoom) else null
 
-        val response = api.getChargepoints(
-            bounds.southwest.latitude, bounds.southwest.longitude,
-            bounds.northeast.latitude, bounds.northeast.longitude,
-            clustering = useClustering, zoom = zoom,
-            clusterDistance = clusterDistance, freecharging = freecharging, minPower = minPower,
-            freeparking = freeparking, plugs = connectors, chargecards = chargeCards,
-            networks = networks
-        )
-
-        if (!response.isSuccessful || response.body()!!.status != "ok") {
-            return Resource.error(response.message(), chargepoints.value?.data)
-        } else {
-            val data = response.body()!!.chargelocations.filter { it ->
-                // apply filters which GoingElectric does not support natively
-                if (it is ChargeLocation) {
-                    it.chargepoints
-                        .filter { it.power >= minPower }
-                        .filter { if (!connectorsVal.all) it.type in connectorsVal.values else true }
-                        .sumBy { it.count } >= minConnectors
+        var startkey: Int? = null
+        val data = mutableListOf<ChargepointListItem>()
+        do {
+            // load all pages of the response
+            try {
+                val response = api.getChargepoints(
+                    bounds.southwest.latitude,
+                    bounds.southwest.longitude,
+                    bounds.northeast.latitude,
+                    bounds.northeast.longitude,
+                    clustering = useGeClustering,
+                    zoom = zoom,
+                    clusterDistance = clusterDistance,
+                    freecharging = freecharging,
+                    minPower = minPower,
+                    freeparking = freeparking,
+                    plugs = connectors,
+                    chargecards = chargeCards,
+                    networks = networks,
+                    startkey = startkey
+                )
+                if (!response.isSuccessful || response.body()!!.status != "ok") {
+                    return Resource.error(response.message(), chargepoints.value?.data)
                 } else {
-                    true
+                    val body = response.body()!!
+                    data.addAll(body.chargelocations)
+                    startkey = body.startkey
                 }
+            } catch (e: IOException) {
+                return Resource.error(e.message, chargepoints.value?.data)
             }
+        } while (startkey != null && startkey < 10000)
 
-            return Resource.success(data)
+        var result = data.filter { it ->
+            // apply filters which GoingElectric does not support natively
+            if (it is ChargeLocation) {
+                it.chargepoints
+                    .filter { it.power >= minPower }
+                    .filter { if (!connectorsVal.all) it.type in connectorsVal.values else true }
+                    .sumBy { it.count } >= minConnectors
+            } else {
+                true
+            }
         }
+        if (!geClusteringAvailable && useClustering) {
+            // apply local clustering if server side clustering is not available
+            Dispatchers.IO.run {
+                result = cluster(result, zoom, clusterDistance!!)
+            }
+        }
+
+        return Resource.success(result)
     }
 
     private fun formatMultipleChoice(connectorsVal: MultipleChoiceFilterValue) =

app/src/main/res/layout/fragment_map.xml

@@ -21,7 +21,7 @@
 
         <fragment
             android:id="@+id/map"
-            android:name="com.google.android.gms.maps.SupportMapFragment"
+            android:name="com.google.android.libraries.maps.SupportMapFragment"
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             tools:context=".MapsActivity" />

app/src/main/res/layout/map_layers.xml

@@ -6,7 +6,7 @@
 
         <import type="net.vonforst.evmap.viewmodel.MapViewModel" />
 
-        <import type="com.google.android.gms.maps.GoogleMap" />
+        <import type="com.google.android.libraries.maps.GoogleMap" />
 
         <variable
             name="vm"

app/src/main/res/values-de/arrays.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string-array name="pref_language_names">
+        <item>Gerätesprache verwenden</item>
+        <item>Englisch</item>
+        <item>Deutsch</item>
+    </string-array>
+</resources>

app/src/main/res/values-de/strings.xml

@@ -90,4 +90,8 @@
     <string name="edit">bearbeiten</string>
     <string name="cancel">Abbrechen</string>
     <string name="ok">OK</string>
+    <string name="pref_language">Sprache</string>
+    <string name="pref_language_summary">App-Sprache ändern</string>
+    <string name="connection_error">Ladesäulen konnten nicht geladen werden</string>
+    <string name="retry">Wiederholen</string>
 </resources>

app/src/main/res/values/arrays.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string-array name="pref_language_names">
+        <item>Device default</item>
+        <item>English</item>
+        <item>German</item>
+    </string-array>
+    <string-array name="pref_language_values" tranlatable="false">
+        <item>default</item>
+        <item>en</item>
+        <item>de</item>
+    </string-array>
+</resources>

app/src/main/res/values/strings.xml

@@ -89,4 +89,8 @@
     <string name="edit">edit</string>
     <string name="cancel">Cancel</string>
     <string name="ok">OK</string>
+    <string name="pref_language">Language</string>
+    <string name="pref_language_summary">Change the app language</string>
+    <string name="connection_error">Could not load charging stations</string>
+    <string name="retry">Retry</string>
 </resources>

app/src/main/res/xml/settings.xml

@@ -10,6 +10,13 @@
             android:summaryOff="@string/pref_navigate_use_maps_off"
             android:defaultValue="true" />
 
+        <ListPreference
+            android:key="language"
+            android:title="@string/pref_language"
+            android:entries="@array/pref_language_names"
+            android:entryValues="@array/pref_language_values"
+            android:defaultValue="default"
+            android:summary="@string/pref_language_summary" />
 
     </PreferenceCategory>
 </PreferenceScreen>

build.gradle

@@ -25,6 +25,9 @@ allprojects {
         google()
         jcenter()
         maven { url 'https://jitpack.io' }
+        flatDir {
+            dirs 'libs'
+        }
     }
 }