I implemented Google OneTap Authentication using FirebaseAuth on my Jetpack Compose application. The problem I face is that after I sign in successfully, if I close my application and start it again I get a NullPointerException caused by my checkAuthState() function which redirects the user to the profile page if it is already authenticated.
Error:
FATAL EXCEPTION: main
Process: com.codrutursache.casey, PID: 28428
java.lang.NullPointerException
at androidx.navigation.NavController.navigate(NavController.kt:1652)
at androidx.navigation.NavController.navigate(NavController.kt:1984)
at androidx.navigation.NavController.navigate$default(NavController.kt:1979)
at com.codrutursache.casey.presentation.MainActivity.navigateToProfileScreen(MainActivity.kt:78)
at com.codrutursache.casey.presentation.MainActivity.checkAuthState(MainActivity.kt:74)
at com.codrutursache.casey.presentation.MainActivity.access$checkAuthState(MainActivity.kt:33)
at com.codrutursache.casey.presentation.MainActivity$onCreate$1.invoke(MainActivity.kt:68)
at com.codrutursache.casey.presentation.MainActivity$onCreate$1.invoke(MainActivity.kt:42)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:108)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
at androidx.compose.ui.platform.ComposeView.Content(ComposeView.android.kt:428)
at androidx.compose.ui.platform.AbstractComposeView$ensureCompositionCreated$1.invoke(ComposeView.android.kt:252)
at androidx.compose.ui.platform.AbstractComposeView$ensureCompositionCreated$1.invoke(ComposeView.android.kt:251)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:108)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
at androidx.compose.runtime.CompositionLocalKt.CompositionLocalProvider(CompositionLocal.kt:228)
at androidx.compose.ui.platform.CompositionLocalsKt.ProvideCommonCompositionLocals(CompositionLocals.kt:195)
at androidx.compose.ui.platform.AndroidCompositionLocals_androidKt$ProvideAndroidCompositionLocals$3.invoke(AndroidCompositionLocals.android.kt:119)
at androidx.compose.ui.platform.AndroidCompositionLocals_androidKt$ProvideAndroidCompositionLocals$3.invoke(AndroidCompositionLocals.android.kt:118)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:108)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
at androidx.compose.runtime.CompositionLocalKt.CompositionLocalProvider(CompositionLocal.kt:228)
at androidx.compose.ui.platform.AndroidCompositionLocals_androidKt.ProvideAndroidCompositionLocals(AndroidCompositionLocals.android.kt:110)
at androidx.compose.ui.platform.WrappedComposition$setContent$1$1$2.invoke(Wrapper.android.kt:158)
at androidx.compose.ui.platform.WrappedComposition$setContent$1$1$2.invoke(Wrapper.android.kt:157)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:108)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
at androidx.compose.runtime.CompositionLocalKt.CompositionLocalProvider(CompositionLocal.kt:228)
at androidx.compose.ui.platform.WrappedComposition$setContent$1$1.invoke(Wrapper.android.kt:157)
at androidx.compose.ui.platform.WrappedComposition$setContent$1$1.invoke(Wrapper.android.kt:142)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:108)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
at androidx.compose.runtime.ActualJvm_jvmKt.invokeComposable(ActualJvm.jvm.kt:78)
at androidx.compose.runtime.ComposerImpl.doCompose(Composer.kt:3340)
at androidx.compose.runtime.ComposerImpl.composeContent$runtime_release(Composer.kt:3273)
at androidx.compose.runtime.CompositionImpl.composeContent(Composition.kt:588)
at androidx.compose.runtime.Recomposer.composeInitial$runtime_release(Recomposer.kt:1013)
at androidx.compose.runtime.CompositionImpl.setContent(Composition.kt:520)
at androidx.compose.ui.platform.WrappedComposition$setContent$1.invoke(Wrapper.android.kt:142)
at androidx.compose.ui.platform.WrappedComposition$setContent$1.invoke(Wrapper.android.kt:133)
2024-01-08 18:13:08.263 28428-28428 AndroidRuntime com.codrutursache.casey E at androidx.compose.ui.platform.AndroidComposeView.setOnViewTreeOwnersAvailable(AndroidComposeView.android.kt:1191)
at androidx.compose.ui.platform.WrappedComposition.setContent(Wrapper.android.kt:133)
at androidx.compose.ui.platform.WrappedComposition.onStateChanged(Wrapper.android.kt:183)
at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.kt:314)
at androidx.lifecycle.LifecycleRegistry.addObserver(LifecycleRegistry.kt:192)
at androidx.compose.ui.platform.WrappedComposition$setContent$1.invoke(Wrapper.android.kt:140)
at androidx.compose.ui.platform.WrappedComposition$setContent$1.invoke(Wrapper.android.kt:133)
at androidx.compose.ui.platform.AndroidComposeView.onAttachedToWindow(AndroidComposeView.android.kt:1266)
at android.view.View.dispatchAttachedToWindow(View.java:21980)
at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3490)
at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3497)
at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3497)
at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3497)
at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3497)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:3014)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:2465)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:9305)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1339)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1348)
at android.view.Choreographer.doCallbacks(Choreographer.java:952)
at android.view.Choreographer.doFrame(Choreographer.java:882)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1322)
at android.os.Handler.handleCallback(Handler.java:958)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loopOnce(Looper.java:205)
at android.os.Looper.loop(Looper.java:294)
at android.app.ActivityThread.main(ActivityThread.java:8177)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:552)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:971)
This is my MainActivity code which handles the auth check and instantiates the navController:
@AndroidEntryPoint
@ExperimentalAnimationApi
class MainActivity : ComponentActivity() {
private lateinit var navController: NavHostController
private lateinit var authViewModel: AuthViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContent {
navController = rememberNavController()
authViewModel = hiltViewModel<AuthViewModel>()
val isBottomBarVisible =
rememberSaveable { mutableStateOf(false) }
CaseyTheme {
isBottomBarVisible.value = when (currentRoute(navController)) {
Route.AuthRoute.route -> false
Route.ProfileRoute.route -> true
else -> true
}
Scaffold(
bottomBar = {
if (isBottomBarVisible.value)
BottomBar(navController = navController)
}
) { paddingValues ->
NavGraph(
navController = navController,
modifier = Modifier.padding(paddingValues)
)
}
}
checkAuthState()
}
}
private fun checkAuthState() {
if (authViewModel.isUserAuthenticated) {
navigateToProfileScreen()
}
}
private fun navigateToProfileScreen() = navController.navigate("profile_screen")
}
@Composable
fun currentRoute(navController: NavController): String? {
val navBackStackEntry by navController.currentBackStackEntryAsState()
return navBackStackEntry?.destination?.route
}
I can't exactly tell where the error is coming from, as you are using a fairly atypical structure in your Activity. You can try to move the
checkAuthState function call into a LaunchedEffect like this:
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContent {
CaseyTheme {
navController = rememberNavController()
authViewModel = hiltViewModel<AuthViewModel>()
val isBottomBarVisible = rememberSaveable { mutableStateOf(false) }
isBottomBarVisible.value = when (currentRoute(navController)) {
Route.AuthRoute.route -> false
Route.ProfileRoute.route -> true
else -> true
}
Scaffold(
bottomBar = {
if (isBottomBarVisible.value)
BottomBar(navController = navController)
}
) { paddingValues ->
LaunchedEffect(Unit) {
checkAuthState()
}
NavGraph(
navController = navController,
modifier = Modifier.padding(paddingValues)
)
}
}
}
}
A typical Activity in Compose looks like this:
class MainActivity : ComponentActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContent {
CaseyTheme {
Surface(
modifier = Modifier.fillMaxSize(),
color = MaterialTheme.colorScheme.background
) {
CaseyApp()
}
}
}
}
}
Then, you place your root Scaffold into the CaseyApp Composable:
@Composable
CaseyApp() {
navController = rememberNavController()
//...
Scaffold(
//...
) { paddingValues ->
LaunchedEffect(Unit) {
checkAuthState()
}
//...
}
}