Iam new to coding in kotlin on android studio and I am currently trying to set up a room database for my project but iam getting a bunch of errors during runtime that iam not sure how to fix. The app is meant to display a list of names in a swipeable pager format, using Jetpack Compose for the UI, Room for local database storage,a ViewModel for app data management ,repository, ViewModelFactory for injecting the repository into view model and a database class for accessing the DAO. Could you please tell me What I am missing or doing wrong?
Here is the list of errors iam receiving:
2024-06-23 10:13:58.120 26589-26589 System com.example.tutorialfollowing
W ClassLoader referenced unknown path: /data/app/com.example.tutorialfollowing-2/lib/x86
2024-06-23 10:13:58.145 26589-26589 AndroidRuntime com.example.tutorialfollowing
D Shutting down VM
2024-06-23 10:13:58.145 26589-26589 AndroidRuntime com.example.tutorialfollowing
E FATAL EXCEPTION: main (Ask Gemini)
Process: com.example.tutorialfollowing, PID: 26589
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tutorialfollowing/com.example.tutorialfollowing.MainActivity}: java.lang.RuntimeException: Cannot find implementation for com.example.tutorialfollowing.AppDatabase. AppDatabase_Impl does not exist
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.RuntimeException: Cannot find implementation for com.example.tutorialfollowing.AppDatabase. AppDatabase_Impl does not exist
at androidx.room.Room.getGeneratedImplementation(Room.kt:58)
at androidx.room.RoomDatabase$Builder.build(RoomDatabase.kt:1351)
at com.example.tutorialfollowing.MainActivity.onCreate(MainActivity.kt:54)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
For context here is the code for my MainActivity.kt:
import android.os.Bundle
import android.content.res.Resources
import android.graphics.Bitmap
import android.graphics.BitmapFactory
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.activity.enableEdgeToEdge
import androidx.activity.viewModels
import androidx.compose.foundation.ExperimentalFoundationApi
import androidx.compose.foundation.Image
import androidx.compose.foundation.background
import androidx.compose.foundation.gestures.Orientation
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.PaddingValues
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.pager.HorizontalPager
import androidx.compose.foundation.pager.rememberPagerState
import androidx.compose.ui.graphics.Color
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.pager.PageSize
import androidx.compose.foundation.pager.PagerDefaults
import androidx.compose.foundation.pager.PagerScope
import androidx.compose.material3.Scaffold
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Text
import androidx.compose.ui.Alignment
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.key
import androidx.compose.runtime.livedata.observeAsState
import androidx.compose.ui.Modifier
import androidx.compose.ui.layout.ContentScale
import androidx.compose.ui.res.painterResource
import androidx.compose.ui.tooling.preview.Preview
import androidx.room.Room
import androidx.compose.ui.unit.dp
import com.example.tutorialfollowing.ui.theme.TutorialFollowingTheme
class MainActivity : ComponentActivity() {
private lateinit var database: AppDatabase
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
database = Room.databaseBuilder(
applicationContext,
AppDatabase::class.java, "names-database"
).build()
val nameDao = database.nameDao()
val repository = NameRepository(nameDao)
val viewModel: NameViewModel by viewModels { NameViewModelFactory(repository) }
setContent {
TutorialFollowingTheme {
val names by viewModel.allNames.observeAsState(emptyList())
NamePagerScreen(names)
}
}
}
}
@OptIn(ExperimentalFoundationApi::class)
@Composable
fun NamePagerScreen(names: List<Name>) {
val pagerState = rememberPagerState(
initialPage = 0,
initialPageOffsetFraction = 0f
) {
names.size
}
Box(modifier = Modifier.fillMaxSize()) {
HorizontalPager(
state = pagerState
) { page ->
val name = names[page]
val background = when (name.gender) {
"Girl" -> R.drawable.pink
"Boy" -> R.drawable.blue
else -> R.drawable.default_background
}
Box(modifier = Modifier.fillMaxSize()) {
Image(
painter = painterResource(id = background),
contentDescription = null,
contentScale = ContentScale.Crop,
modifier = Modifier.fillMaxSize()
)
Box(
modifier = Modifier
.align(Alignment.Center)
.background(Color(0x80000000))
.fillMaxWidth()
.padding(16.dp)
) {
Text(
text = "${name.childFirstName} - ${name.gender}",
style = MaterialTheme.typography.headlineMedium,
color = Color.White,
modifier = Modifier.align(Alignment.Center)
)
}
}
}
}
}
@Preview(showBackground = true)
@Composable
fun DefaultPreview() {
TutorialFollowingTheme {
NamePagerScreen(
listOf(
Name(1, 2020, "Girl", "Asian", "Lily", 10, 1),
Name(2, 2020, "Boy", "Hispanic", "Joel", 8, 2)
)
)
}
}
here is my data class 'Name.kt':
import androidx.room.ColumnInfo
import androidx.room.Entity
import androidx.room.PrimaryKey
@Entity(tableName = "names")
data class Name(
@PrimaryKey(autoGenerate = true) val nameId: Int,
@ColumnInfo(name = "year_of_birth") val yearOfBirth: Int,
@ColumnInfo(name = "gender") val gender: String,
@ColumnInfo(name = "ethnicity") val ethnicity: String,
@ColumnInfo(name = "child_first_name") val childFirstName: String,
@ColumnInfo(name = "count") val count: Int,
@ColumnInfo(name = "rank") val rank: Int
)
Database class 'appDatabase'
import androidx.room.Database
import androidx.room.RoomDatabase
@Database(entities = [Name::class], version = 1)
abstract class AppDatabase: RoomDatabase(){
abstract fun nameDao(): NameDao
}
DAO interface file 'NameDao':
import androidx.room.Dao
import androidx.room.Insert
import androidx.room.Query
import kotlinx.coroutines.flow.Flow
@Dao
interface NameDao {
@Query("SELECT * FROM names")
fun getAll(): Flow<List<Name>>
@Insert
fun insertAll(vararg names: Name)
}
class 'NameRepository':
import androidx.annotation.WorkerThread import kotlinx.coroutines.flow.Flow
class NameRepository(private val nameDao: NameDao) {
val allNames: Flow<List<Name>> = nameDao.getAll()
@WorkerThread
suspend fun insert(name: Name) {
nameDao.insertAll(name)
}
} Class 'NameViewModel':
import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import kotlinx.coroutines.launch
class NameViewModel (private val repository: NameRepository) : ViewModel() {
private val _allNames = MutableLiveData<List<Name>>()
val allNames: LiveData<List<Name>> = _allNames
init {
viewModelScope.launch {
repository.allNames.collect { names ->
_allNames.value = names
}
}
}
fun insert(name: Name) = viewModelScope.launch {
repository.insert(name)
}
}
class file 'NameViewModelFactory' :
import androidx.lifecycle.ViewModel
import androidx.lifecycle.ViewModelProvider
class NameViewModelFactory(private val repository: NameRepository) : ViewModelProvider.NewInstanceFactory() {
override fun <T : ViewModel> create(modelClass: Class<T>): T {
if (modelClass.isAssignableFrom(NameViewModel::class.java)) {
@Suppress("UNCHECKED_CAST")
return NameViewModel(repository) as T
}
throw IllegalArgumentException("Unknown ViewModel class")
}
}
libs.Versions.toml:
[versions]
agp = "8.4.1"
kotlin = "1.9.0"
coreKtx = "1.13.1"
junit = "4.13.2"
junitVersion = "1.1.5"
espressoCore = "3.5.1"
lifecycleRuntimeKtx = "2.8.1"
activityCompose = "1.9.0"
composeBom = "2023.08.00"
room = "2.6.1"
roomCommon = "2.6.1"
runtimeLivedata = "1.6.8"
org-jetbrains-kotlin-android = "1.8.0"
[libraries]
androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
junit = { group = "junit", name = "junit", version.ref = "junit" }
androidx-junit = { group = "androidx.test.ext", name = "junit", version.ref = "junitVersion" }
androidx-espresso-core = { group = "androidx.test.espresso", name = "espresso-core", version.ref = "espressoCore" }
androidx-lifecycle-runtime-ktx = { group = "androidx.lifecycle", name = "lifecycle-runtime-ktx", version.ref = "lifecycleRuntimeKtx" }
androidx-activity-compose = { group = "androidx.activity", name = "activity-compose", version.ref = "activityCompose" }
androidx-compose-bom = { group = "androidx.compose", name = "compose-bom", version.ref = "composeBom" }
androidx-ui = { group = "androidx.compose.ui", name = "ui" }
androidx-ui-graphics = { group = "androidx.compose.ui", name = "ui-graphics" }
androidx-ui-tooling = { group = "androidx.compose.ui", name = "ui-tooling" }
androidx-ui-tooling-preview = { group = "androidx.compose.ui", name = "ui-tooling-preview" }
androidx-ui-test-manifest = { group = "androidx.compose.ui", name = "ui-test-manifest" }
androidx-ui-test-junit4 = { group = "androidx.compose.ui", name = "ui-test-junit4" }
androidx-material3 = { group = "androidx.compose.material3", name = "material3" }
room-ktx = { group = "androidx.room", name = "room-ktx", version.ref = "room" }
androidx-room-common = { group = "androidx.room", name = "room-common", version.ref = "roomCommon" }
androidx-runtime-livedata = { group = "androidx.compose.runtime", name = "runtime-livedata", version.ref = "runtimeLivedata" }
[plugins]
android-application = { id = "com.android.application", version.ref = "agp" }
jetbrains-kotlin-android = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }
org-jetbrains-kotlin-kapt = { id = "org.jetbrains.kotlin.kapt", version.ref = "org-jetbrains-kotlin-android" }
Build.gradle.kts(App):
plugins {
alias(libs.plugins.android.application) apply false
alias(libs.plugins.jetbrains.kotlin.android) apply false
alias(libs.plugins.org.jetbrains.kotlin.kapt) apply false
}
Build.gradle.kts(module):
plugins {
alias(libs.plugins.android.application)
alias(libs.plugins.jetbrains.kotlin.android)
alias(libs.plugins.org.jetbrains.kotlin.kapt)
}
android {
namespace = "com.example.tutorialfollowing"
compileSdk = 34
defaultConfig {
applicationId = "com.example.tutorialfollowing"
minSdk = 24
targetSdk = 34
versionCode = 1
versionName = "1.0"
testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
vectorDrawables {
useSupportLibrary = true
}
}
buildTypes {
release {
isMinifyEnabled = false
proguardFiles(
getDefaultProguardFile("proguard-android-optimize.txt"),
"proguard-rules.pro"
)
}
}
compileOptions {
sourceCompatibility = JavaVersion.VERSION_1_8
targetCompatibility = JavaVersion.VERSION_1_8
}
kotlinOptions {
jvmTarget = "1.8"
}
buildFeatures {
compose = true
dataBinding =true
}
composeOptions {
kotlinCompilerExtensionVersion = "1.5.1"
}
packaging {
resources {
excludes += "/META-INF/{AL2.0,LGPL2.1}"
}
}
}
dependencies {
implementation(libs.androidx.core.ktx)
implementation(libs.androidx.lifecycle.runtime.ktx)
implementation(libs.androidx.activity.compose)
implementation(platform(libs.androidx.compose.bom))
implementation(libs.androidx.ui)
implementation(libs.androidx.ui.graphics)
implementation(libs.androidx.ui.tooling.preview)
implementation(libs.androidx.material3)
implementation(libs.androidx.room.common)
implementation(libs.room.ktx)
implementation(libs.androidx.runtime.livedata)
testImplementation(libs.junit)
androidTestImplementation(libs.androidx.junit)
androidTestImplementation(libs.androidx.espresso.core)
androidTestImplementation(platform(libs.androidx.compose.bom))
androidTestImplementation(libs.androidx.ui.test.junit4)
debugImplementation(libs.androidx.ui.tooling)
debugImplementation(libs.androidx.ui.test.manifest)
}
From some source I have found online of people getting similar errors is that there may be due to some kind of misconfiguration in the project setup. I have tried changing it but was still getting the same errors.
You need to add the necessary dependencies room-compiler and room-runtime, upgrade Kotlin to version 2.0.0 and add the KSP plugin.
In build.gradle.kts(:app)
plugins {
//...
alias(libs.plugins.kotlinAndroidKsp)
}
dependecies {
// ...
implementation(libs.androidx.room.ktx)
implementation(libs.androidx.room.runtime)
ksp(libs.androidx.room.compiler)
}
build.gradle.kts(project)
plugins {
// ...
alias(libs.plugins.kotlinAndroidKsp) apply false
}
libs.versions.toml
[versions]
kotlin = "2.0.0"
room = "2.6.1"
ksp = "2.0.0-1.0.22"
[libraries]
androidx-room-ktx = { group = "androidx.room", name = "room-ktx", version.ref = "room" }
androidx-room-compiler = { group = "androidx.room", name = "room-compiler", version.ref = "room" }
androidx-room-runtime = { group = "androidx.room", name = "room-runtime", version.ref = "room" }
[plugins]
kotlinAndroidKsp = { id = "com.google.devtools.ksp", version.ref = "ksp" }