Develop Reference

How to get LiveData from Room?

I'm trying to get LiveData from Room. So my RecycleView can have Live updates if anything in database is changed
I have tried with out LiveData and that works, but when i add LiveData that always shows this error.
error: Not sure how to convert a Cursor to this method's return type (androidx.lifecycle.LiveData<java.util.List<com.example.models.Club>>).
public abstract java.lang.Object getAll(#org.jetbrains.annotations.NotNull()
I googled and looked on this site for solution, but every on with this issue have used rxjava, rxandroid, rxkotlin or ArrayList.
And for them solution is to replace ArrayList with List, and for RX to try coroutine.
Well i am using Coroutine and List and still no progress.
This is my ClubDao
ClubDao
#Query("SELECT * FROM club")
suspend fun getAll(): LiveData<List<Club>>
In Club i have this attributes
Club
#Entity
data class Club(#PrimaryKey var id: Int,
#ColumnInfo(name = "logo_url") var logoUrl: String,
#ColumnInfo(name = "name") var name: String,
#ColumnInfo(name = "town") var town: String,
#ColumnInfo(name = "address") var address: String,
#ColumnInfo(name = "contact_name") var contactName: String,
#ColumnInfo(name = "phone_numbers") var phoneNumbers: String,
#ColumnInfo(name = "email") var email: String)
phoneNumbers should be List, but i convert those to and from json with TypeConverters
TypeConverter is here
TypeConverter
class ConvertersDB {
#TypeConverter
fun fromString(value: String): ArrayList<String> {
val listType = object : TypeToken<ArrayList<String>>() {
}.type
return Gson().fromJson(value, listType)
}
#TypeConverter
fun fromArrayList(list: ArrayList<String>): String {
val gson = Gson()
return gson.toJson(list)
}
}
And my DB
DataBase
#Database(entities = [Club::class], version = 1, exportSchema = false)
#TypeConverters(ConvertersDB::class)
abstract class AppDatabase : RoomDatabase() {
abstract fun clubDao(): ClubDao
companion object {
#Volatile
private var instance: AppDatabase? = null
private val LOCK = Any()
operator fun invoke(context: Context) = instance ?: synchronized(LOCK) {
instance ?: buildDatabase(context).also { instance = it }
}
private fun buildDatabase(context: Context) = Room.databaseBuilder(context,
AppDatabase::class.java, "pss.db")
.allowMainThreadQueries()
.build()
}
}
In my fragment i need to observe all the clubs from database via ViewModel and Repository and send them to RecycleView
Now i am getting error:
error: Not sure how to convert a Cursor to this method's return type (androidx.lifecycle.LiveData<java.util.List<com.example.models.Club>>).
public abstract java.lang.Object getAll(#org.jetbrains.annotations.NotNull()
Does anyone know solution for this?
EDIT:
Gradle
apply plugin: 'com.android.application'
apply plugin: 'androidx.navigation.safeargs'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'
android {
compileSdkVersion 28
defaultConfig {
applicationId "com.overswayit.plesnisavezsrbije"
minSdkVersion 24
targetSdkVersion 28
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}
dataBinding {
enabled true
}
packagingOptions {
exclude 'META-INF/atomicfu.kotlin_module'
}
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.31"
implementation 'com.jakewharton:butterknife:10.1.0'
implementation 'com.google.android.material:material:1.1.0-alpha07'
implementation 'androidx.cardview:cardview:1.0.0'
implementation 'androidx.appcompat:appcompat:1.1.0-beta01'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
implementation 'androidx.legacy:legacy-support-v4:1.0.0'
// Room components
implementation "androidx.room:room-runtime:$rootProject.roomVersion"
implementation "androidx.room:room-ktx:$rootProject.roomVersion"
kapt "androidx.room:room-compiler:$rootProject.roomVersion"
androidTestImplementation "androidx.room:room-testing:$rootProject.roomVersion"
// Room and RxJava
implementation "androidx.room:room-rxjava2:$rootProject.roomVersion"
// Lifecycle components
implementation "androidx.lifecycle:lifecycle-extensions:$rootProject.archLifecycleVersion"
kapt "androidx.lifecycle:lifecycle-compiler:$rootProject.archLifecycleVersion"
androidTestImplementation "androidx.arch.core:core-testing:$rootProject.androidxArchVersion"
// ViewModel Kotlin support
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$rootProject.archLifecycleVersion"
//LiveData Kotlin
implementation "androidx.lifecycle:lifecycle-livedata:$rootProject.archLifecycleVersion"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:$rootProject.archLifecycleVersion"
implementation "androidx.lifecycle:lifecycle-runtime-ktx:$rootProject.archLifecycleVersion"
// Coroutines
api "org.jetbrains.kotlinx:kotlinx-coroutines-core:$rootProject.coroutines"
api "org.jetbrains.kotlinx:kotlinx-coroutines-android:$rootProject.coroutines"
//RxJava
implementation 'io.reactivex.rxjava2:rxandroid:2.1.1'
implementation "io.reactivex.rxjava2:rxjava:2.2.6"
implementation 'com.jakewharton.rxbinding3:rxbinding:3.0.0-alpha2'
implementation "org.jetbrains.kotlin:kotlin-stdlib:1.3.31"
annotationProcessor 'com.jakewharton:butterknife-compiler:10.1.0'
implementation 'com.squareup.picasso:picasso:2.71828'
implementation 'com.kaopiz:kprogresshud:1.0.5'
implementation 'com.squareup:otto:1.3.8'
implementation 'agency.tango.android:avatar-view:0.0.2'
implementation 'agency.tango.android:avatar-view-picasso:0.0.2'
implementation 'com.mikhaellopez:circularimageview:3.2.0'
implementation 'com.googlecode.libphonenumber:libphonenumber:8.1.0'
// Data Binding
kapt "com.android.databinding:compiler:3.1.4"
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test:runner:1.2.0'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
implementation project(path: ':tuple')
// Navigation Component
implementation 'androidx.navigation:navigation-fragment-ktx:2.0.0'
implementation 'androidx.navigation:navigation-ui-ktx:2.0.0'
//Gson
implementation 'com.google.code.gson:gson:2.8.5'
}
kapt {
generateStubs = true
}
Top Level Gradle
buildscript {
repositories {
google()
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:3.4.1'
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.31"
classpath "android.arch.navigation:navigation-safe-args-gradle-plugin:1.0.0"
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
allprojects {
repositories {
google()
jcenter()
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}
ext {
roomVersion = '2.1.0'
archLifecycleVersion = '2.2.0-alpha01'
androidxArchVersion = '2.0.0'
coroutines = '1.2.0'
}

As mentioned in the comments, remove suspend.
When a method returns an observable, there is no reason to make it suspend since it just returns and object, does not run any query until it is observed.
#Query("SELECT * FROM club")
fun getAll(): LiveData<List<Club>>
Room's coroutines integration brings ability to return suspend values but when the value itself is asnyc, there is no reason to use it.

I found a good solution to the problem with using rxJava with room and livedata.
The approach is similar to using Retrofit with RxJava, using LiveDataReactiveStreams, which
by default uses flowable.
In your approach i would recomend is:
#Query("SELECT * FROM club")
suspend fun getAll(): LiveData<List<Club>>
changed to
DAO:
#Query("SELECT * FROM club")
fun getAll(): (Any rxJava object) Flowable<List<Club>>
Repository:
fun getAllClubs() : LiveData<List<Club>>{
return LiveDataReactiveStreams.fromPublisher(dao.getAll()"do any transformation or
other functionality you want and then if using Maybe for example transform to
flowable by .toFlowable()")
}
ViewModel:
val clubList : MediatorLiveData<List<Club>>()
fun setClubData(){
clubList.addSource(repository.getAllClubs(), {
clubList.value = it
})
}
then you can observe the livedata object as usual in your view.
Hope what i wrote is understandable, if not i will try to make it better :)

Putting generic parameter clazz to RealmQuery when parameter is getting from generic function overrited

Actually I'm writing a repository pattern with Kotlin for an Android Studio project. I have a generic interface named "BaseRepository". This interface is extended from "BaseRealmRepository" and others.
I need to get all results from Realm.db into findAll(), but I can't modify this inherited function because it is generic in other repositories.
When I try, I am getting the following error:
"fun findAllRealm
(
clazz: Class
)
: List
is not satisfied: inferred type GenericRealmModelType<> is not a subtype of RealmModel"*
but my real problem is clazz parameter of Class, that I need do cast or something for pass to "where" clausule of realmQuery without modify the generic function adding upper bounds like or similar
This is my generic interface:
interface BaseRepository<T> {
fun create(item: T) : T
fun remove(item: T)
fun update(item: T) : T
fun find(item: T): T
fun <T> findAll(clazz: Class<T>): List<T>
}
I'm created a generic type for do cast:
interface GenericRealmModelType<out T: RealmModel>{}
And finally, my abstract class "BaseObjectsRealmRepository" that is extended from "BaseRepository":
abstract class BaseObjectsRealmRepository<T> : BaseRepository<T> {
...
override fun <T> findAll(clazz: Class<T>): List<T> {
var klazz: Class<GenericRealmModelType<*>> = clazz as Class<GenericRealmModelType<*>>
val allResults = findAllRealm(klazz)
return allResults
}
private fun <T: RealmModel> findAllRealm(clazz: Class<T>): List<T>{
val realm = Realm.getDefaultInstance()
val realmResults = realm
.where(clazz) //CLAZZ IS MY PROBLEM
.findAll()
val allResults: List<T> = realm.copyFromRealm(realmResults)
return allResults
}
}
The project configuration is the following:
Project build.gradle:
buildscript {
ext.kotlin_version = '1.2.41'
repositories {
google()
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:3.1.2'
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
classpath "io.realm:realm-gradle-plugin:5.1.0"
classpath 'com.google.gms:google-services:3.2.0'
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
allprojects {
repositories {
google()
jcenter()
maven {
url "https://maven.google.com"
}
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}
Module app build.gradle:
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'
apply plugin: 'realm-android'
android {
compileSdkVersion 27
defaultConfig {
applicationId "com.example.example"
minSdkVersion 16
targetSdkVersion 27
versionCode 1
versionName "1.0"
testInstrumentationRunner
"android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'),
'proguard-rules.pro'
}
}
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
implementation 'com.android.support:appcompat-v7:27.1.1'
implementation 'com.android.support.constraint:constraint-layout:1.1.0'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.2'
androidTestImplementation 'com.android.support.test.espresso:espresso-
core:3.0.2'
implementation 'com.google.dagger:dagger-android:2.12'
implementation 'com.google.dagger:dagger-android-support:2.12'
kapt 'com.google.dagger:dagger-android-processor:2.12'
kapt 'com.google.dagger:dagger-compiler:2.13'
implementation 'com.android.support:support-annotations:27.1.1'
implementation 'com.google.firebase:firebase-auth:15.1.0'
implementation 'com.google.android.gms:play-services-auth:15.0.1'
implementation 'com.google.firebase:firebase-core:15.0.2'
implementation 'com.android.support:support-v4:27.1.1'
implementation 'com.android.support:recyclerview-v7:27.1.1'
implementation 'com.android.support:design:27.1.1'
}
realm {
syncEnabled = true
}
repositories {
mavenCentral()
}
// Add to the bottom of the file
apply plugin: 'com.google.gms.google-services'
What can I do?
Thank you!

I believe you can solve this problem by removing interface GenericRealmModelType<out T: RealmModel>{} entirely.
abstract class BaseObjectsRealmRepository<T> : BaseRepository<T> {
...
override fun <T> findAll(clazz: Class<T>): List<T> =
Realm.getDefaultInstance().use { r ->
r.copyFromRealm(r.where(clazz).findAll())
}

I'm get the solution for this:
BaseObjectsrealmRepository:
Change this:
Old:
abstract class BaseObjectsRealmRepository : BaseRepository {
New:
abstract class BaseObjectsRealmRepository constructor(clazz: Class): BaseRepository {
And now the next code:
override fun findAll(clazz: Class<T>): List<T> {
val allResults = findAllRealm(clazz)
return allResults
}
private fun findAllRealm(clazz: Class<T>): List<T>{
val realm = Realm.getDefaultInstance()
val realmResults = realm
.where(clazz)
.findAll()
val allResults: List<T> = realm.copyFromRealm(realmResults)
return allResults
}
Thank you!

ParcelCreator lint suppression not working

I'm trying to add Parcelize implementation but it doesn't seem to be working.
This is whaat my project's gradle looks like:
buildscript {
ext.kotlin_version = '1.2.30'
repositories {
maven { url "https://jitpack.io" }
google()
jcenter() }
dependencies {
classpath 'com.android.tools.build:gradle:3.1.0'
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
//Realm as ORM
classpath "io.realm:realm-gradle-plugin:4.3.3"
}
}
allprojects {
repositories {
maven { url "https://jitpack.io" }
google()
jcenter()
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}
App's build gradle:
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'
apply plugin: 'realm-android'
android {
compileSdkVersion 27
defaultConfig {
applicationId "com.----.----"
minSdkVersion 21
targetSdkVersion 27
multiDexEnabled true
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
kapt {
generateStubs = true
}
dependencies {
def supportVersion = '27.1.0'
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.support:appcompat-v7:' + supportVersion
implementation 'com.android.support:preference-v14:' + supportVersion
implementation 'com.android.support:support-v4:' + supportVersion
implementation 'com.android.support:design:' + supportVersion
implementation 'com.android.support.constraint:constraint-layout:1.0.2'
testImplementation 'junit:junit:4.12'
//noinspection GradleCompatible
androidTestImplementation 'com.android.support.test:runner:1.0.1'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
implementation "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
// Dagger 2
implementation 'com.google.dagger:dagger:2.14.1'
kapt 'com.google.dagger:dagger-compiler:2.14.1'
// Retrofit
implementation 'com.squareup.retrofit2:retrofit:2.4.0'
implementation 'com.squareup.retrofit2:adapter-rxjava2:2.4.0'
implementation 'com.squareup.retrofit2:converter-moshi:2.4.0'
implementation 'com.squareup.moshi:moshi-kotlin:1.5.0'
//Rx
implementation 'io.reactivex.rxjava2:rxandroid:2.0.2'
implementation 'io.reactivex.rxjava2:rxjava:2.1.9'
implementation 'io.reactivex.rxjava2:rxkotlin:2.2.0'
//Glide
implementation 'com.github.bumptech.glide:glide:4.6.1'
implementation 'jp.wasabeef:glide-transformations:3.1.1'
kapt 'com.github.bumptech.glide:compiler:4.6.1'
//Recycler view, Card view
implementation 'com.android.support:recyclerview-v7:27.1.0'
implementation 'com.android.support:cardview-v7:27.1.0'
//video player
implementation 'com.google.android.exoplayer:exoplayer:r2.5.1'
//circle image view
implementation 'de.hdodenhof:circleimageview:2.2.0'
//page indicator
implementation 'com.romandanylyk:pageindicatorview:1.0.0'
//spinner
implementation 'com.jaredrummler:material-spinner:1.2.4'
}
repositories {
mavenCentral()
}
And this is the model where I am trying to implement Parcelize:
#SuppressLint("ParcelCreator")
#Parcelize
data class StatusMessagesSender(#Json(name = "firstName")
val firstName: String?,
#Json(name = "lastName")
val lastName: String?,
#Json(name = "pushDeviceToken")
val pushDeviceToken: String?,
#Json(name = "address")
val address: String?,
#Json(name = "phoneNumber")
val phoneNumber: String?,
#Json(name = "name")
val name: String?,
#Json(name = "userId")
val userId: String?,
#Json(name = "age")
val age: Int?,
#Json(name = "email")
val email: String?): Parcelable
So even if I add this annotation #SuppressLint("ParcelCreator"), nothing changes.. It still gives me the same error without it:
"Class 'StatusMessagesSender' is not abstract and does not implement abstract member public abstract fun writeToParcel(dest: Parcel!, flags: Int): Unit defined in android.os.Parcelable"
Anyone can tell if I did something wrong here?

Put the next code inside android { } in the file build.gradle of your App.
androidExtensions {
experimental = true
}

This is a known issue you can ignore and it's fixed with kotlin 1.2.31, so just update kotlin in your gradle file

Room Persistence lib implementation in Kotlin(Gradle error)

I am implementing Room persistence lib in kotlin for my database implementation.
Same question is asked in Android Room Persistences library and Kotlin thread, applying those solution resulted in different gradle errors:
Following are my Entity, Dao and Database classes:
Food.kt
#Entity
class Food(#ColumnInfo(name = "food_name") var foodName: String,
#ColumnInfo(name = "food_desc") var foodDesc: String,
#ColumnInfo(name = "protein") var protein: Double,
#ColumnInfo(name = "carbs") var carbs: Double,
#ColumnInfo(name = "fat") var fat: Double)
{
#ColumnInfo(name = "id")
#PrimaryKey(autoGenerate = true)
var id: Long = 0
#ColumnInfo(name = "calories")
var calories: Double = 0.toDouble()
}
PersonalizedFood.kt
#Entity(primaryKeys = arrayOf("food_id","date"))
class PersonalizedFood(#ColumnInfo(name = "quantity") var quantity: Int,
#ColumnInfo(name = "unit") var unit: String,
#ColumnInfo(name = "date") var date: Date){
#ColumnInfo(name = "food_id")
var foodId:Long = 0
}
FoodDao.kt
#Dao
interface FoodDao {
companion object{
const val ID = "id"
const val NAME = "name"
const val PROTEIN = "protein"
const val DESC = "desc"
const val CARBS = "carbs"
const val FAT = "fat"
const val DATE = "date"
const val FOOD_ID = "food_id"
const val ALL_FOOD_LIST = "food"
const val PERSONALISED_FOOD_LIST = "personalised_food"
}
/**
* Returns food details of a food given by food_id
*/
#Query("SELECT * FROM $ALL_FOOD_LIST WHERE $ID=:food_id")
fun getFoodDetails(food_id:Long):Food
/**
* Inserts food items in all_food_list
*/
#Insert
fun addFoodList(list:ArrayList<Food>)
#Insert(onConflict = REPLACE)
fun saveFood(food:PersonalizedFood)
#Query("SELECT * FROM $PERSONALISED_FOOD_LIST WHERE $FOOD_ID=:foodId and $DATE=:date")
fun getFood(foodId:Int, data:Date):PersonalizedFood
#Query("SELECT * FROM $ALL_FOOD_LIST where $ID in (select $FOOD_ID from $PERSONALISED_FOOD_LIST where $DATE = :date)")
fun getFood(date:Date):ArrayList<Food>
}
Converter.kt
class Converter {
companion object{
#TypeConverter
fun fromTimestamp(value: Long?): Date? {
return if (value == null) null else Date(value)
}
#TypeConverter
fun dateToTimestamp(date: Date): Long {
return date.time
}
}
}
FoodDatabase.kt
#Database(entities = arrayOf(Food::class, PersonalizedFood::class), version = 1)
#TypeConverters(Converter::class)
abstract class FoodDatabase : RoomDatabase(){
abstract fun foodDao():FoodDao
companion object{
private val databaseName = "diet"
var dbInstance:FoodDao? = null
fun getInstance(context:Context):FoodDao?{
if(dbInstance == null)
dbInstance = Room.inMemoryDatabaseBuilder(context, FoodDatabase::class.java).build().foodDao()
return dbInstance;
}
}
}
And when i run following code to create database:
FoodDatabase.getInstance(baseContext)?.getFood(Calendar.getInstance().time)
It gives me following exception:
Caused by: java.lang.RuntimeException: cannot find implementation for com.chandilsachin.diettracker.database.FoodDatabase. FoodDatabase_Impl does not exist
at android.arch.persistence.room.Room.getGeneratedImplementation(Room.java:90)
at android.arch.persistence.room.RoomDatabase$Builder.build(RoomDatabase.java:340)
at com.chandilsachin.diettracker.database.FoodDatabase$Companion.getInstance(FoodDatabase.kt:21)
at com.chandilsachin.diettracker.MainActivity$SetUpFoodDatabase.doInBackground(MainActivity.kt:95)
at com.chandilsachin.diettracker.MainActivity$SetUpFoodDatabase.doInBackground(MainActivity.kt:77)
at android.os.AsyncTask$2.call(AsyncTask.java:295)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234) 
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588) 
at java.lang.Thread.run(Thread.java:818) 
Has anyone implemented room persistence in kotlin?
Edited
My previous question on same topic was marked duplicate of this. Though problem statement is same but solution given does not solve my problem. Solution says i have to add replace annotationProcessor to kapt "android.arch.persistence.room:compiler:1.0.0-alpha1" dependency. I made those changes and it resulted in gradle error while project build.
Information:Gradle tasks [:app:assembleDebug]
Warning:warning: Supported source version 'RELEASE_7' from annotation processor 'android.arch.persistence.room.RoomProcessor' less than -source '1.8'
Warning:warning: The following options were not recognized by any processor: '[kapt.kotlin.generated]'
/Users/BBI-M1025/Documents/BBI/Workspace_fun/Android/diet-tracker/app/src/main/java/com/chandilsachin/diettracker/database/Food.kt
Error:(1, 1) Some error(s) occurred while processing annotations. Please see the error messages above.
Error:Execution failed for task ':app:kaptDebugKotlin'.
> Compilation error. See log for more details
Information:BUILD FAILED in 10s
Information:2 errors
Information:2 warnings
Information:See complete output in console
I am attaching my gradle file also:
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'
android {
compileSdkVersion 25
buildToolsVersion "25.0.2"
defaultConfig {
applicationId "com.chandilsachin.diettracker"
minSdkVersion 16
targetSdkVersion 25
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
compile 'com.android.support:appcompat-v7:25.0.1'
compile 'com.android.support.constraint:constraint-layout:1.0.0-alpha8'
compile 'com.android.support:cardview-v7:25.0.1'
compile 'com.android.support:recyclerview-v7:25.0.1'
compile 'com.github.ne1c:rainbowmvp:1.2.1'
compile "org.jetbrains.anko:anko-commons:0.10.0"
/*annotationProcessor "android.arch.persistence.room:compiler:1.0.0-alpha1"
compile "android.arch.lifecycle:extensions:1.0.0-alpha1"
annotationProcessor "android.arch.lifecycle:compiler:1.0.0-alpha1"*/
compile "android.arch.persistence.room:runtime:1.0.0-alpha1"
annotationProcessor "android.arch.persistence.room:compiler:1.0.0-alpha1"
kapt "android.arch.persistence.room:compiler:1.0.0-alpha1"
testCompile 'junit:junit:4.12'
}
repositories {
mavenCentral()
}
Has anyone come across this issue?

After spinning my head around for a while with this problem, I came across to the solution.
It was really hard as there is no official tutorial, blog etc out there to help with this problem as of now.
I had to do several hit and trial for all the combination of gradle plugins and dependencies as i knew that something is wrong with gradle config only.
Lets come to the solution:
I had to remove apply plugin: 'kotlin-kapt' from build.gradle(:module) file
and replace annotationProcessor "android.arch.persistence.room:compiler:1.0.0-alpha1" to kapt "android.arch.persistence.room:compiler:1.0.0-alpha1".
This is the gradle configuration to successfully compile code.
But there more things to check. You have to initialise properties of your #Entity class unlike java given in Room Persistence lib doc. Though there are getter setter but it is not mentioned to create a constructor with initialisation.
So I had to change my #Entity class with this:
#Entity(tableName = "all_food_list")
class Food (#ColumnInfo(name = "food_name") var foodName: String = "",
#ColumnInfo(name = "food_desc") var foodDesc: String = "",
#ColumnInfo(name = "protein") var protein: Double = 0.0,
#ColumnInfo(name = "carbs") var carbs: Double = 0.0,
#ColumnInfo(name = "fat") var fat: Double = 0.0,
#ColumnInfo(name = "calories") var calories: Double = 0.0)
{
#ColumnInfo(name = "id")
#PrimaryKey(autoGenerate = true)
var id: Long = 0
}
Now for TypeConverts, Unlike java, you need to create normal function not static functions(companion object):
class Converters{
#TypeConverter
fun fromTimestamp(value: String): Calendar {
val arr = value.split("-")
val cal = Calendar.getInstance()
cal.set(arr[0].toInt(), arr[1].toInt(), arr[2].toInt())
return cal
}
#TypeConverter
fun dateToTimestamp(date: Calendar): String {
return "${date.get(Calendar.DATE)}-${date.get(Calendar.MONTH)+1}-${date.get(Calendar.YEAR)}"
}
}
I am adding build.gradle file also to make it more clear:
build.gradle(:project)
buildscript {
ext.kotlin_version = '1.1.2-4'
ext.gradle_version_stable = '2.3.2'
ext.gradle_version_preview = '3.0.0-alpha1'
ext.anko_version = '0.10.0'
repositories {
maven { url 'https://maven.google.com' }
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:3.0.0-alpha1'
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
allprojects {
repositories {
maven { url 'https://maven.google.com' }
jcenter()
maven { url "https://jitpack.io" }
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}
build.gradle(:module)
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
android {
compileSdkVersion 25
buildToolsVersion "25.0.2"
defaultConfig {
applicationId "com.chandilsachin.diettracker"
minSdkVersion 16
targetSdkVersion 25
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
...
...
// room persistence dependency
compile "android.arch.persistence.room:runtime:1.0.0-alpha1"
kapt "android.arch.persistence.room:compiler:1.0.0-alpha1"
testCompile 'junit:junit:4.12'
}
repositories {
mavenCentral()
}
I think this is all, I did to make my code woking.
Hope this helps someone else also.

man just add the following in the build.gradle. Above dependencies :D
kapt {
generateStubs = true
}

Room Persistence lib implementation in Kotlin

I am implementing Room persistence lib in kotlin for my database implementation.
Following are my Entity, Dao and Database classes:
Food.kt
#Entity
class Food(#ColumnInfo(name = "food_name") var foodName: String,
#ColumnInfo(name = "food_desc") var foodDesc: String,
#ColumnInfo(name = "protein") var protein: Double,
#ColumnInfo(name = "carbs") var carbs: Double,
#ColumnInfo(name = "fat") var fat: Double)
{
#ColumnInfo(name = "id")
#PrimaryKey(autoGenerate = true)
var id: Long = 0
#ColumnInfo(name = "calories")
var calories: Double = 0.toDouble()
}
PersonalizedFood.kt
#Entity(primaryKeys = arrayOf("food_id","date"))
class PersonalizedFood(#ColumnInfo(name = "quantity") var quantity: Int,
#ColumnInfo(name = "unit") var unit: String,
#ColumnInfo(name = "date") var date: Date){
#ColumnInfo(name = "food_id")
var foodId:Long = 0
}
FoodDao.kt
#Dao
interface FoodDao {
companion object{
const val ID = "id"
const val NAME = "name"
const val PROTEIN = "protein"
const val DESC = "desc"
const val CARBS = "carbs"
const val FAT = "fat"
const val DATE = "date"
const val FOOD_ID = "food_id"
const val ALL_FOOD_LIST = "food"
const val PERSONALISED_FOOD_LIST = "personalised_food"
}
/**
* Returns food details of a food given by food_id
*/
#Query("SELECT * FROM $ALL_FOOD_LIST WHERE $ID=:food_id")
fun getFoodDetails(food_id:Long):Food
/**
* Inserts food items in all_food_list
*/
#Insert
fun addFoodList(list:ArrayList<Food>)
#Insert(onConflict = REPLACE)
fun saveFood(food:PersonalizedFood)
#Query("SELECT * FROM $PERSONALISED_FOOD_LIST WHERE $FOOD_ID=:foodId and $DATE=:date")
fun getFood(foodId:Int, data:Date):PersonalizedFood
#Query("SELECT * FROM $ALL_FOOD_LIST where $ID in (select $FOOD_ID from $PERSONALISED_FOOD_LIST where $DATE = :date)")
fun getFood(date:Date):ArrayList<Food>
}
Converter.kt
class Converter {
companion object{
#TypeConverter
fun fromTimestamp(value: Long?): Date? {
return if (value == null) null else Date(value)
}
#TypeConverter
fun dateToTimestamp(date: Date): Long {
return date.time
}
}
}
FoodDatabase.kt
#Database(entities = arrayOf(Food::class, PersonalizedFood::class), version = 1)
#TypeConverters(Converter::class)
abstract class FoodDatabase : RoomDatabase(){
abstract fun foodDao():FoodDao
companion object{
private val databaseName = "diet"
var dbInstance:FoodDao? = null
fun getInstance(context:Context):FoodDao?{
if(dbInstance == null)
dbInstance = Room.inMemoryDatabaseBuilder(context, FoodDatabase::class.java).build().foodDao()
return dbInstance;
}
}
}
And when i run following code to create database:
FoodDatabase.getInstance(baseContext)?.getFood(Calendar.getInstance().time)
It gives me following exception:
Caused by: java.lang.RuntimeException: cannot find implementation for
com.chandilsachin.diettracker.database.FoodDatabase. FoodDatabase_Impl
does not exist
at
android.arch.persistence.room.Room.getGeneratedImplementation(Room.java:90)
at
android.arch.persistence.room.RoomDatabase$Builder.build(RoomDatabase.java:340)
at
com.chandilsachin.diettracker.database.FoodDatabase$Companion.getInstance(FoodDatabase.kt:21)
at
com.chandilsachin.diettracker.MainActivity$SetUpFoodDatabase.doInBackground(MainActivity.kt:95)
at
com.chandilsachin.diettracker.MainActivity$SetUpFoodDatabase.doInBackground(MainActivity.kt:77)
at android.os.AsyncTask$2.call(AsyncTask.java:295)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234) 
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113) 
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588) 
at java.lang.Thread.run(Thread.java:818)
Has anyone implemented room persistence in kotlin?
Edited
This question was marked duplicate of this. Though problem statement is same but solution given does not solve my problem. Solution says i have to add replace annotationProcessor to kapt "android.arch.persistence.room:compiler:1.0.0-alpha1" dependency. I made those changes and it resulted in gradle error while project build.
Information:Gradle tasks [:app:assembleDebug] Warning:warning:
Supported source version 'RELEASE_7' from annotation processor
'android.arch.persistence.room.RoomProcessor' less than -source '1.8'
Warning:warning: The following options were not recognized by any
processor: '[kapt.kotlin.generated]'
/Users/BBI-M1025/Documents/BBI/Workspace_fun/Android/diet-tracker/app/src/main/java/com/chandilsachin/diettracker/database/Food.kt
Error:(1, 1) Some error(s) occurred while processing annotations. Please see the error messages above.
Error:Execution failed for task ':app:kaptDebugKotlin'.
Compilation error. See log for more details
Information:BUILD FAILED in 10s
Information:2 errors
Information:2 warnings
Information:See complete output in console
I am attaching my gradle file also:
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'
android {
compileSdkVersion 25
buildToolsVersion "25.0.2"
defaultConfig {
applicationId "com.chandilsachin.diettracker"
minSdkVersion 16
targetSdkVersion 25
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
compile 'com.android.support:appcompat-v7:25.0.1'
compile 'com.android.support.constraint:constraint-layout:1.0.0-alpha8'
compile 'com.android.support:cardview-v7:25.0.1'
compile 'com.android.support:recyclerview-v7:25.0.1'
compile 'com.github.ne1c:rainbowmvp:1.2.1'
compile "org.jetbrains.anko:anko-commons:0.10.0"
/*annotationProcessor "android.arch.persistence.room:compiler:1.0.0-alpha1"
compile "android.arch.lifecycle:extensions:1.0.0-alpha1"
annotationProcessor "android.arch.lifecycle:compiler:1.0.0-alpha1"*/
compile "android.arch.persistence.room:runtime:1.0.0-alpha1"
annotationProcessor "android.arch.persistence.room:compiler:1.0.0-alpha1"
kapt "android.arch.persistence.room:compiler:1.0.0-alpha1"
testCompile 'junit:junit:4.12'
}
repositories {
mavenCentral()
}
Has anyone come across this issue?

After spinning my head around for a while with this problem, I came across to the solution.
It was really hard as there is no official tutorial, blog etc out there to help with this problem as of now.
I had to do several hit and trial for all the combination of gradle plugins and dependencies as i knew that something is wrong with gradle config only.
Lets come to the solution:
I had to remove apply plugin: 'kotlin-kapt' from build.gradle(:module) file
and replace annotationProcessor "android.arch.persistence.room:compiler:1.0.0-alpha1" to kapt "android.arch.persistence.room:compiler:1.0.0-alpha1".
This is the gradle configuration to successfully compile code.
But there more things to check. You have to initialise properties of your #Entity class unlike java given in Room Persistence lib doc. Though there are getter setter but it is not mentioned to create a constructor with initialisation.
So I had to change my #Entity class with this:
#Entity(tableName = "all_food_list")
class Food (#ColumnInfo(name = "food_name") var foodName: String = "",
#ColumnInfo(name = "food_desc") var foodDesc: String = "",
#ColumnInfo(name = "protein") var protein: Double = 0.0,
#ColumnInfo(name = "carbs") var carbs: Double = 0.0,
#ColumnInfo(name = "fat") var fat: Double = 0.0,
#ColumnInfo(name = "calories") var calories: Double = 0.0)
{
#ColumnInfo(name = "id")
#PrimaryKey(autoGenerate = true)
var id: Long = 0
}
Now for TypeConverts, Unlike java, you need to create normal function not static functions(companion object):
class Converters{
#TypeConverter
fun fromTimestamp(value: String): Calendar {
val arr = value.split("-")
val cal = Calendar.getInstance()
cal.set(arr[0].toInt(), arr[1].toInt(), arr[2].toInt())
return cal
}
#TypeConverter
fun dateToTimestamp(date: Calendar): String {
return "${date.get(Calendar.DATE)}-${date.get(Calendar.MONTH)+1}-${date.get(Calendar.YEAR)}"
}
}
I am adding build.gradle file also to make it more clear:
build.gradle(:project)
buildscript {
ext.kotlin_version = '1.1.2-4'
ext.gradle_version_stable = '2.3.2'
ext.gradle_version_preview = '3.0.0-alpha1'
ext.anko_version = '0.10.0'
repositories {
maven { url 'https://maven.google.com' }
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:3.0.0-alpha1'
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
allprojects {
repositories {
maven { url 'https://maven.google.com' }
jcenter()
maven { url "https://jitpack.io" }
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}
build.gradle(:module)
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
android {
compileSdkVersion 25
buildToolsVersion "25.0.2"
defaultConfig {
applicationId "com.chandilsachin.diettracker"
minSdkVersion 16
targetSdkVersion 25
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
...
...
// room persistence dependency
compile "android.arch.persistence.room:runtime:1.0.0-alpha1"
kapt "android.arch.persistence.room:compiler:1.0.0-alpha1"
testCompile 'junit:junit:4.12'
}
repositories {
mavenCentral()
}
I think this is all, I did to make my code woking.
Hope this helps someone else also.

Here my gradle files, i didn't need to add thoses plugins.
build.gradle(project):
buildscript {
ext.kotlin_version = '1.1.2-4'
ext.lifecycle_version = '1.0.0-alpha1'
ext.room_version = '1.0.0-alpha1'
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:2.3.2'
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
}
}
build.gradle (app)
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
//enable anotation processing with kotlin, disabled by default
kapt {
generateStubs = true
}
android {
/**
...
**/
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
//kotlin
compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
//support
compile 'com.android.support:appcompat-v7:25.3.1'
//google architecture
compile "android.arch.lifecycle:runtime:$lifecycle_version"
compile "android.arch.lifecycle:extensions:$lifecycle_version"
annotationProcessor "android.arch.lifecycle:compiler:$lifecycle_version"
kapt "android.arch.lifecycle:compiler:$lifecycle_version"
//database
compile "android.arch.persistence.room:runtime:$room_version"
annotationProcessor "android.arch.persistence.room:compiler:$room_version"
kapt "android.arch.persistence.room:compiler:$room_version"
}
repositories {
mavenCentral()
}
Then run menu build-> make project to create impl class.
Hope this helps

I made an example similar using Java and used to have same problem and solution was add APT line apt "android.arch.persistence.room:compiler:1.0.0-alpha1"
without apply: apply plugin: 'kotlin-kapt'. Remove this line!!
You have to clear project and rebuild it before run again and try uninstall existing app on phone or Virtual device.
Hope you help.

I got the same issue when I try to migrate from Java to Kotlin:
RuntimeException: cannot find implementation for AppDatabase. AppDatabase_Impl does not exist
I tried all these answers in this question, none all them works, then I found an article: Kotlinlang Tutorials - Android Frameworks Using Annotation Processing:
In Kotlin you specify the dependencies in a similar to Java way using Kotlin Annotation processing tool (kapt) instead of annotationProcessor.
Then I modified the build.gradle(Module:app) by changing all annotationProcessor to kapt, it works:
--- a/app/build.gradle
+++ b/app/build.gradle
## -2,6 +2,8 ## apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-kapt'
apply plugin: 'kotlin-android-extensions'
android {
// Butter Knife
implementation "com.jakewharton:butterknife:$butterknife_version"
- annotationProcessor "com.jakewharton:butterknife-compiler:$butterknife_version"
+ kapt "com.jakewharton:butterknife-compiler:$butterknife_version"
// Room
implementation "android.arch.persistence.room:runtime:$arch_lifecycle_version"
- annotationProcessor "android.arch.persistence.room:compiler:$arch_lifecycle_version"
+ kapt "android.arch.persistence.room:compiler:$arch_lifecycle_version"
// LifeCycle
implementation "android.arch.lifecycle:runtime:$arch_lifecycle_version"
implementation "android.arch.lifecycle:extensions:$arch_lifecycle_version"
implementation "android.arch.lifecycle:common-java8:$arch_lifecycle_version"
- annotationProcessor "android.arch.lifecycle:compiler:$arch_lifecycle_version"
+ kapt "android.arch.lifecycle:compiler:$arch_lifecycle_version"
// Dagger
implementation "com.google.dagger:dagger:$dagger_version"
implementation "com.google.dagger:dagger-android-support:$dagger_version"
- annotationProcessor "com.google.dagger:dagger-compiler:$dagger_version"
- annotationProcessor "com.google.dagger:dagger-android-processor:$dagger_version"
+ kapt "com.google.dagger:dagger-compiler:$dagger_version"
+ kapt "com.google.dagger:dagger-android-processor:$dagger_version"
}
If you use Butter Knife, you should also change to kapt, otherwise the views which are injected might be null.

in the Dao interface check that the annotations like #Query .. are imported from the room database class and not from somewhere else