How to import Room into Android Studio correctly?

I am having problems importing Room into Android Studio correctly. I created a little Counter App, in which the count should be stored in a database. My files for importing Room are:

build.gradle.kts (Project):

plugins {
    alias(libs.plugins.android.application)
    alias(libs.plugins.kotlin.compose)
    id("com.google.devtools.ksp")
}

android {
    namespace = "com.example.counter"
    compileSdk {
        version = release(36) {
            minorApiLevel = 1
        }
    }
    
    defaultConfig {
        applicationId = "com.example.counter"
        minSdk = 24
        targetSdk = 36
        versionCode = 1
        versionName = "1.0"

        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            isMinifyEnabled = false
            proguardFiles(
                getDefaultProguardFile("proguard-android-optimize.txt"),
                "proguard-rules.pro"
            )
        }
    }
    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_11
        targetCompatibility = JavaVersion.VERSION_11
    }
    buildFeatures {
        compose = true
    }
}

dependencies {
    implementation(libs.room.compiler)
    ksp(libs.androidx.room.compiler)
    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.compose.ui)
    implementation(libs.androidx.compose.ui.graphics)
    implementation(libs.androidx.compose.ui.tooling.preview)
    implementation(libs.androidx.compose.material3)
    implementation(libs.androidx.lifecycle.viewmodel.compose)
    testImplementation(libs.junit)
    androidTestImplementation(libs.androidx.junit)
    androidTestImplementation(libs.androidx.espresso.core)
    androidTestImplementation(platform(libs.androidx.compose.bom))
    androidTestImplementation(libs.androidx.compose.ui.test.junit4)
    debugImplementation(libs.androidx.compose.ui.tooling)
    debugImplementation(libs.androidx.compose.ui.test.manifest)
}

build.gradle.kts (Module: app)

// Top-level build file where you can add configuration options common to all sub-projects/modules.
plugins {
    alias(libs.plugins.android.application) apply false
    alias(libs.plugins.kotlin.compose) apply false
    id("com.google.devtools.ksp") version "2.3.4" apply false
}

libs.versions.toml

[versions]
agp = "9.2.0"
coreKtx = "1.10.1"
junit = "4.13.2"
junitVersion = "1.1.5"
espressoCore = "3.5.1"
lifecycleRuntimeKtx = "2.6.1"
activityCompose = "1.8.0"
kotlin = "2.2.10"
composeBom = "2026.02.01"
lifecycleViewmodelCompose = "2.10.0"
roomCompiler = "2.5.0"
roomRuntime = "2.8.4"
roomCompilerVersion = "2.8.4"

[libraries]
androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
androidx-lifecycle-viewmodel-compose = { module = "androidx.lifecycle:lifecycle-viewmodel-compose", version.ref = "lifecycleViewmodelCompose" }
androidx-room-compiler = { module = "androidx.room:room-compiler", version.ref = "roomCompiler" }
androidx-room-runtime = { module = "androidx.room:room-runtime", version.ref = "roomRuntime" }
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-compose-ui = { group = "androidx.compose.ui", name = "ui" }
androidx-compose-ui-graphics = { group = "androidx.compose.ui", name = "ui-graphics" }
androidx-compose-ui-tooling = { group = "androidx.compose.ui", name = "ui-tooling" }
androidx-compose-ui-tooling-preview = { group = "androidx.compose.ui", name = "ui-tooling-preview" }
androidx-compose-ui-test-manifest = { group = "androidx.compose.ui", name = "ui-test-manifest" }
androidx-compose-ui-test-junit4 = { group = "androidx.compose.ui", name = "ui-test-junit4" }
androidx-compose-material3 = { group = "androidx.compose.material3", name = "material3" }
room-compiler = { group = "androidx.room", name = "room-compiler", version.ref = "roomCompilerVersion" }

[plugins]
android-application = { id = "com.android.application", version.ref = "agp" }
kotlin-compose = { id = "org.jetbrains.kotlin.plugin.compose", version.ref = "kotlin" }

When I try to code a room database, I get the errors:

  • Illegal annotation class 'Entity'

  • Unresolved reference 'PrimaryKey'

package com.example.counter.counter.data
import androidx.room.vo.Entity

@Entity
data class Counter(
    @PrimaryKey val id: Int = 0,
    val count: Int)

Did I import Room correctly and if not, how do I achive that?

2
Apr 30 at 10:54 AM
User AvatarBenedikt Schlüter
#android#kotlin#android-room

Accepted Answer

In your TOML, you have:

androidx-room-runtime = { module = "androidx.room:room-runtime", version.ref = "roomRuntime" }

However, you never reference it.

In your module's dependencies closure, you have:

    implementation(libs.room.compiler)
    ksp(libs.androidx.room.compiler)

As shown in the documentation, your first line is supposed to be for the runtime:

    implementation(libs.androidx.room.runtime)
    ksp(libs.androidx.room.compiler)
User AvatarCommonsWare
Apr 30 at 11:00 AM
2