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社区首页 >问答首页 >导航jetpack组合时应用程序崩溃

问导航jetpack组合时应用程序崩溃
EN

Stack Overflow用户
提问于 2022-02-06 18:22:54
回答 2查看 2.2K关注 0票数 3

我总共有两个屏幕，即SplashScreen和BottomNavScreen(带有底部导航)。BottomNavScreen有两个屏幕，即Screen1和Screen2。

我想从SplashScreen返回到Screen2，但是在导航到SplashScreen时我得到了这个错误。

代码语言：javascript
运行
复制
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.lool, PID: 8610
    java.lang.IllegalStateException: ViewModelStore should be set before setGraph call
        at androidx.navigation.NavController.setViewModelStore(NavController.kt:2164)
        at androidx.navigation.NavHostController.setViewModelStore(NavHostController.kt:101)
        at androidx.navigation.compose.NavHostKt.NavHost(NavHost.kt:106)
        at androidx.navigation.compose.NavHostKt.NavHost(NavHost.kt:69)
        at com.example.lool.NavigationKt.BottomNav(navigation.kt:34)
        at com.example.lool.screens.Bottom_nav_screenKt$BottomNavScreen$2.invoke(bottom_nav_screen.kt:31)
        at com.example.lool.screens.Bottom_nav_screenKt$BottomNavScreen$2.invoke(bottom_nav_screen.kt:30)
        at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:116)
        at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:34)
        at androidx.compose.material.ScaffoldKt$ScaffoldLayout$1$1$1$bodyContentPlaceables$1.invoke(Scaffold.kt:316)
        at androidx.compose.material.ScaffoldKt$ScaffoldLayout$1$1$1$bodyContentPlaceables$1.invoke(Scaffold.kt:314)
        at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:107)
        at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:34)
        at androidx.compose.ui.layout.SubcomposeLayoutState$subcompose$2$1$1.invoke(SubcomposeLayout.kt:241)
        at androidx.compose.ui.layout.SubcomposeLayoutState$subcompose$2$1$1.invoke(SubcomposeLayout.kt:241)
        at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:107)
        at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:34)
        at androidx.compose.runtime.ComposerKt.invokeComposable(Composer.kt:3330)
        at androidx.compose.runtime.ComposerImpl$doCompose$2$5.invoke(Composer.kt:2577)
        at androidx.compose.runtime.ComposerImpl$doCompose$2$5.invoke(Composer.kt:2573)
        at androidx.compose.runtime.SnapshotStateKt.observeDerivedStateRecalculations(SnapshotState.kt:540)
        at androidx.compose.runtime.ComposerImpl.doCompose(Composer.kt:2566)
        at androidx.compose.runtime.ComposerImpl.composeContent$runtime_release(Composer.kt:2517)
        at androidx.compose.runtime.CompositionImpl.composeContent(Composition.kt:476)
        at androidx.compose.runtime.Recomposer.composeInitial$runtime_release(Recomposer.kt:727)
        at androidx.compose.runtime.ComposerImpl$CompositionContextImpl.composeInitial$runtime_release(Composer.kt:2980)
        at androidx.compose.runtime.CompositionImpl.setContent(Composition.kt:432)
        at androidx.compose.ui.layout.SubcomposeLayoutState.subcomposeInto(SubcomposeLayout.kt:259)
        at androidx.compose.ui.layout.SubcomposeLayoutState.access$subcomposeInto(SubcomposeLayout.kt:145)
        at androidx.compose.ui.layout.SubcomposeLayoutState$subcompose$2.invoke(SubcomposeLayout.kt:234)
        at androidx.compose.ui.layout.SubcomposeLayoutState$subcompose$2.invoke(SubcomposeLayout.kt:231)
        at androidx.compose.runtime.snapshots.SnapshotStateObserver.withNoObservations(SnapshotStateObserver.kt:144)
        at androidx.compose.ui.node.OwnerSnapshotObserver.withNoSnapshotReadObservation$ui_release(OwnerSnapshotObserver.kt:49)
        at androidx.compose.ui.node.LayoutNode.withNoSnapshotReadObservation$ui_release(LayoutNode.kt:1107)
        at androidx.compose.ui.layout.SubcomposeLayoutState.subcompose(SubcomposeLayout.kt:231)
        at androidx.compose.ui.layout.SubcomposeLayoutState.subcompose(SubcomposeLayout.kt:226)
        at androidx.compose.ui.layout.SubcomposeLayoutState.subcompose$ui_release(SubcomposeLayout.kt:215)
        at androidx.compose.ui.layout.SubcomposeLayoutState$Scope.subcompose(SubcomposeLayout.kt:466)
        at androidx.compose.material.ScaffoldKt$ScaffoldLayout$1$1$1.invoke(Scaffold.kt:314)
        at androidx.compose.material.ScaffoldKt$ScaffoldLayout$1$1$1.invoke(Scaffold.kt:241)
        at androidx.compose.ui.layout.MeasureScope$layout$1.placeChildren(MeasureScope.kt:68)
E/AndroidRuntime:     at androidx.compose.ui.layout.SubcomposeLayoutState$createMeasurePolicy$1$measure$1.placeChildren(SubcomposeLayout.kt:357)
        at androidx.compose.ui.node.LayoutNode$layoutChildren$1.invoke(LayoutNode.kt:925)
        at androidx.compose.ui.node.LayoutNode$layoutChildren$1.invoke(LayoutNode.kt:915)
        at androidx.compose.runtime.snapshots.SnapshotStateObserver.observeReads(SnapshotStateObserver.kt:128)
        at androidx.compose.ui.node.OwnerSnapshotObserver.observeReads$ui_release(OwnerSnapshotObserver.kt:75)
        at androidx.compose.ui.node.OwnerSnapshotObserver.observeLayoutSnapshotReads$ui_release(OwnerSnapshotObserver.kt:56)
        at androidx.compose.ui.node.LayoutNode.layoutChildren$ui_release(LayoutNode.kt:915)
        at androidx.compose.ui.node.LayoutNode.onNodePlaced$ui_release(LayoutNode.kt:901)
        at androidx.compose.ui.node.InnerPlaceable.placeAt-f8xVGno(InnerPlaceable.kt:94)
        at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:31)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50(Placeable.kt:370)
        at androidx.compose.ui.node.OuterMeasurablePlaceable.placeAt-f8xVGno(OuterMeasurablePlaceable.kt:149)
        at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:31)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50(Placeable.kt:370)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50$default(Placeable.kt:203)
        at androidx.compose.foundation.layout.BoxKt.placeInBox(Box.kt:186)
        at androidx.compose.foundation.layout.BoxKt.access$placeInBox(Box.kt:1)
        at androidx.compose.foundation.layout.BoxKt$boxMeasurePolicy$1$measure$2.invoke(Box.kt:126)
        at androidx.compose.foundation.layout.BoxKt$boxMeasurePolicy$1$measure$2.invoke(Box.kt:125)
        at androidx.compose.ui.layout.MeasureScope$layout$1.placeChildren(MeasureScope.kt:68)
        at androidx.compose.ui.node.LayoutNode$layoutChildren$1.invoke(LayoutNode.kt:925)
        at androidx.compose.ui.node.LayoutNode$layoutChildren$1.invoke(LayoutNode.kt:915)
        at androidx.compose.runtime.snapshots.SnapshotStateObserver.observeReads(SnapshotStateObserver.kt:128)
        at androidx.compose.ui.node.OwnerSnapshotObserver.observeReads$ui_release(OwnerSnapshotObserver.kt:75)
        at androidx.compose.ui.node.OwnerSnapshotObserver.observeLayoutSnapshotReads$ui_release(OwnerSnapshotObserver.kt:56)
        at androidx.compose.ui.node.LayoutNode.layoutChildren$ui_release(LayoutNode.kt:915)
        at androidx.compose.ui.node.LayoutNode.onNodePlaced$ui_release(LayoutNode.kt:901)
        at androidx.compose.ui.node.InnerPlaceable.placeAt-f8xVGno(InnerPlaceable.kt:94)
        at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:31)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50(Placeable.kt:370)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50$default(Placeable.kt:203)
        at androidx.compose.ui.node.DelegatingLayoutNodeWrapper$measure$1$1.placeChildren(DelegatingLayoutNodeWrapper.kt:123)
        at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.placeAt-f8xVGno(DelegatingLayoutNodeWrapper.kt:111)
        at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:31)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50(Placeable.kt:370)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50$default(Placeable.kt:203)
        at androidx.compose.ui.node.DelegatingLayoutNodeWrapper$measure$1$1.placeChildren(DelegatingLayoutNodeWrapper.kt:123)
        at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.placeAt-f8xVGno(DelegatingLayoutNodeWrapper.kt:111)
        at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:31)
        at androidx.compose.ui.layout.Placeable$PlacementScope.placeWithLayer(Placeable.kt:393)
        at androidx.compose.ui.layout.Placeable$PlacementScope.placeWithLayer$default(Placeable.kt:266)
        at androidx.compose.ui.graphics.SimpleGraphicsLayerModifier$measure$1.invoke(GraphicsLayerModifier.kt:221)
E/AndroidRuntime:     at androidx.compose.ui.graphics.SimpleGraphicsLayerModifier$measure$1.invoke(GraphicsLayerModifier.kt:220)
        at androidx.compose.ui.layout.MeasureScope$layout$1.placeChildren(MeasureScope.kt:68)
        at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.placeAt-f8xVGno(DelegatingLayoutNodeWrapper.kt:111)
        at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:31)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50(Placeable.kt:370)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50$default(Placeable.kt:203)
        at androidx.compose.ui.node.DelegatingLayoutNodeWrapper$measure$1$1.placeChildren(DelegatingLayoutNodeWrapper.kt:123)
        at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.placeAt-f8xVGno(DelegatingLayoutNodeWrapper.kt:111)
        at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:31)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50(Placeable.kt:370)
        at androidx.compose.ui.node.OuterMeasurablePlaceable.placeAt-f8xVGno(OuterMeasurablePlaceable.kt:149)
        at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:31)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50(Placeable.kt:370)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50$default(Placeable.kt:203)
        at androidx.compose.foundation.layout.BoxKt.placeInBox(Box.kt:186)
        at androidx.compose.foundation.layout.BoxKt.access$placeInBox(Box.kt:1)
        at androidx.compose.foundation.layout.BoxKt$boxMeasurePolicy$1$measure$2.invoke(Box.kt:126)
        at androidx.compose.foundation.layout.BoxKt$boxMeasurePolicy$1$measure$2.invoke(Box.kt:125)
        at androidx.compose.ui.layout.MeasureScope$layout$1.placeChildren(MeasureScope.kt:68)
        at androidx.compose.ui.node.LayoutNode$layoutChildren$1.invoke(LayoutNode.kt:925)
        at androidx.compose.ui.node.LayoutNode$layoutChildren$1.invoke(LayoutNode.kt:915)
        at androidx.compose.runtime.snapshots.SnapshotStateObserver.observeReads(SnapshotStateObserver.kt:128)
        at androidx.compose.ui.node.OwnerSnapshotObserver.observeReads$ui_release(OwnerSnapshotObserver.kt:75)
        at androidx.compose.ui.node.OwnerSnapshotObserver.observeLayoutSnapshotReads$ui_release(OwnerSnapshotObserver.kt:56)
        at androidx.compose.ui.node.LayoutNode.layoutChildren$ui_release(LayoutNode.kt:915)
        at androidx.compose.ui.node.LayoutNode.onNodePlaced$ui_release(LayoutNode.kt:901)
        at androidx.compose.ui.node.InnerPlaceable.placeAt-f8xVGno(InnerPlaceable.kt:94)
        at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:31)
        at androidx.compose.ui.layout.Placeable$PlacementScope.placeWithLayer(Placeable.kt:393)
        at androidx.compose.ui.layout.Placeable$PlacementScope.placeWithLayer$default(Placeable.kt:266)
        at androidx.compose.ui.graphics.BlockGraphicsLayerModifier$measure$1.invoke(GraphicsLayerModifier.kt:164)
        at androidx.compose.ui.graphics.BlockGraphicsLayerModifier$measure$1.invoke(GraphicsLayerModifier.kt:163)
        at androidx.compose.ui.layout.MeasureScope$layout$1.placeChildren(MeasureScope.kt:68)
        at androidx.compose.ui.node.DelegatingLayoutNodeWrapper.placeAt-f8xVGno(DelegatingLayoutNodeWrapper.kt:111)
        at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:31)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50(Placeable.kt:370)
        at androidx.compose.ui.node.OuterMeasurablePlaceable.placeAt-f8xVGno(OuterMeasurablePlaceable.kt:149)
        at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:31)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50(Placeable.kt:370)
        at androidx.compose.ui.layout.Placeable$PlacementScope.place-70tqf50$default(Placeable.kt:203)
        at androidx.compose.foundation.layout.BoxKt.placeInBox(Box.kt:186)
        at androidx.compose.foundation.layout.BoxKt.access$placeInBox(Box.kt:1)
        at androidx.compose.foundation.layout.BoxKt$boxMeasurePolicy$1$measure$5.invoke(Box.kt:167)
E/AndroidRuntime:     at androidx.compose.foundation.layout.BoxKt$boxMeasurePolicy$1$measure$5.invoke(Box.kt:163)
        at androidx.compose.ui.layout.MeasureScope$layout$1.placeChildren(MeasureScope.kt:68)
        at androidx.compose.ui.node.LayoutNode$layoutChildren$1.invoke(LayoutNode.kt:925)
        at androidx.compose.ui.node.LayoutNode$layoutChildren$1.invoke(LayoutNode.kt:915)
        at androidx.compose.runtime.snapshots.Snapshot$Companion.observe(Snapshot.kt:1776)
        at androidx.compose.runtime.snapshots.SnapshotStateObserver.observeReads(SnapshotStateObserver.kt:123)
        at androidx.compose.ui.node.OwnerSnapshotObserver.observeReads$ui_release(OwnerSnapshotObserver.kt:75)
        at androidx.compose.ui.node.OwnerSnapshotObserver.observeLayoutSnapshotReads$ui_release(OwnerSnapshotObserver.kt:56)
        at androidx.compose.ui.node.LayoutNode.layoutChildren$ui_release(LayoutNode.kt:915)
        at androidx.compose.ui.node.LayoutNode.onNodePlaced$ui_release(LayoutNode.kt:901)
        at androidx.compose.ui.node.InnerPlaceable.placeAt-f8xVGno(InnerPlaceable.kt:94)
        at androidx.compose.ui.layout.Placeable.access$placeAt-f8xVGno(Placeable.kt:31)
        at androidx.compose.ui.layout.Placeable$PlacementScope.placeWithLayer-aW-9-wM(Placeable.kt:396)
        at androidx.compose.ui.node.OuterMeasurablePlaceable.placeAt-f8xVGno(OuterMeasurablePlaceable.kt:151)
        at androidx.compose.ui.node.OuterMeasurablePlaceable.replace(OuterMeasurablePlaceable.kt:161)
        at androidx.compose.ui.node.LayoutNode.replace$ui_release(LayoutNode.kt:811)
        at androidx.compose.ui.node.MeasureAndLayoutDelegate.measureAndLayout(MeasureAndLayoutDelegate.kt:215)
        at androidx.compose.ui.platform.AndroidComposeView.measureAndLayout(AndroidComposeView.android.kt:510)
        at androidx.compose.ui.platform.AndroidComposeView.dispatchDraw(AndroidComposeView.android.kt:666)
        at android.view.View.draw(View.java:22707)
        at android.view.View.updateDisplayListIfDirty(View.java:21579)
        at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:4512)
        at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:4485)
        at android.view.View.updateDisplayListIfDirty(View.java:21535)
        at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:4512)
        at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:4485)
        at android.view.View.updateDisplayListIfDirty(View.java:21535)
        at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:4512)
        at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:4485)
        at android.view.View.updateDisplayListIfDirty(View.java:21535)
        at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:4512)
        at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:4485)
        at android.view.View.updateDisplayListIfDirty(View.java:21535)
        at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:534)
        at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:540)
        at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:616)
        at android.view.ViewRootImpl.draw(ViewRootImpl.java:4457)
        at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:4177)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:3337)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:2145)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:8724)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1037)
        at android.view.Choreographer.doCallbacks(Choreographer.java:845)
        at android.view.Choreographer.doFrame(Choreographer.java:780)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1022)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loopOnce(Looper.java:201)
        at android.os.Looper.loop(Looper.java:288)
        at android.app.ActivityThread.main(ActivityThread.java:7813)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)

这是我的MainActivity.kt

代码语言：javascript
运行
复制
class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            LoolTheme {
                // A surface container using the 'background' color from the theme
                StartNav()
            }
        }
    }
}

这是我的Navigation.kt

代码语言：javascript
运行
复制
@Composable
fun StartNav() {
    val navController = rememberNavController();
    val bottomNavController = rememberNavController();

    NavHost(navController = navController, startDestination = "splash_screen") {
        composable("splash_screen") {
            SplashScreen(navController)
        }
        composable("bottom_nav_screen") {
            BottomNavScreen(
                navController = navController,
                bottomNavHostController = bottomNavController
            )
        }
    }
}


@Composable
fun BottomNav(bottomNavController: NavHostController, navController: NavHostController) {
    NavHost(navController = bottomNavController, startDestination = "screen_1") {
        composable("screen_1") {
            Screen1()
        }
        composable("screen_2") {
            Screen2(navController)
        }
    }
}

这是我的SplashScreen.kt

代码语言：javascript
运行
复制
@Composable
fun SplashScreen(navController: NavController) {
    LaunchedEffect(key1 = true) {
        delay(2000L)
        navController.navigate("bottom_nav_screen")
    }

    Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
        Text("Splash Screen")
    }
}

这是我的BottomNavScreen.kt

代码语言：javascript
运行
复制
var navItems = listOf<NavItem>(
    NavItem(label = "uyguy", route = "screen_1", icon = Icons.Filled.Add),
    NavItem(label = "fvvf", route = "screen_2", icon = Icons.Filled.AddCircle)
)

@Composable
fun BottomNavScreen(
    navController: NavHostController,
    bottomNavHostController: NavHostController,

    ) {
    Scaffold(
        bottomBar = {
            BottomNavBar(items = navItems, navController = bottomNavHostController, onClick = {
                bottomNavHostController.navigate(it.route)
            })
        }
    ) {
        BottomNav(navController = navController, bottomNavController = bottomNavHostController)
    }
}

这是我的Screen1.kt和Screen2.kt

代码语言：javascript
运行
复制
@Composable
fun Screen1(){
    Column(
        modifier = Modifier.fillMaxSize(),
        verticalArrangement = Arrangement.Center,
        horizontalAlignment = Alignment.CenterHorizontally,

        ) {
        Text("1st Screen ", fontSize = 64.sp)
    }
}


@Composable
fun Screen2(navController: NavController) {
    Column(
        modifier = Modifier.fillMaxSize(),
        verticalArrangement = Arrangement.Center,
        horizontalAlignment = Alignment.CenterHorizontally,

        ) {
        Text("2nd Screen Logout ", fontSize = 64.sp, modifier = Modifier.clickable {
            navController.navigate("splash_screen") {

            }
        })
    }
}
android-jetpack-compose
android-jetpack-navigation
android
kotlin
EN

回答 2

Stack Overflow用户

发布于 2022-02-07 13:13:10

调用navigate时，默认情况下它会向导航堆栈添加一个新视图。这并不总是预期的行为--您的资源将不会被释放，当用户单击“后退”时，他将看到前面的屏幕。我想这不是你在注销后所期望的。

这也是导致您崩溃的原因之一--无论是使用索引1的逆堆栈视图还是使用当前索引3的新视图都使用导航控制器的相同状态。

在这种情况下，您需要在导航期间指定一些参数，例如清除导航堆栈，如下所示：

代码语言：javascript
运行
复制
navController.navigate("splash_screen") {
    popUpTo("splash_screen") {
        inclusive = true
    }
}

您还可以将启动屏幕从堆栈中取出，例如，当您不注销时，但是将启动屏幕显示为某种信息屏幕。

即使有了这个修复，您的应用程序仍然会崩溃。但问题似乎与这样一个事实有关:您将bottomNavHostController的定义与它的NavHost分开，因此在不需要重用该NavController时会重用它。

我不确定这是一个bug还是一个预期的行为。我建议您使用报告来查看维护人员对它的看法。

最简单的解决方案是摆脱第二个“`NavHost”，例如，参见嵌套导航。

另一种解决方案是将bottomNavHostController声明从StartNav移到BottomNavScreen，或者在composable("bottom_nav_screen")内部(实际上是相同的)，因此简短的修复如下：

代码语言：javascript
运行
复制
composable("bottom_nav_screen") {
    val bottomNavHostController = rememberNavController()
    BottomNavScreen(
        navController = navController,
        bottomNavHostController = bottomNavHostController,
    )
}
票数 3
EN

Stack Overflow用户

发布于 2022-02-07 17:08:55

这是我更新的代码。作曲

我在我的navHost上面做了一个脚手架，在那里我创建了bottomNavbar。

这一行将决定是否显示bottomNavBar

如果(currentRoute !in items)返回@Scaffold

MainActivity.kt

代码语言：javascript
运行
复制
class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            LoolTheme {
                var navItems = listOf<NavItem>(
                    NavItem(label = "label_1", route = "screen_1", icon = Icons.Filled.Add),
                    NavItem(label = "label_2", route = "screen_2", icon = Icons.Filled.AddCircle)
                )
                val navController = rememberNavController()
                Scaffold(
                    bottomBar = {
                        val items = navItems.map {
                            it.route
                        }
                        val navBackStackEntry by navController.currentBackStackEntryAsState()
                        val currentRoute =
                            navBackStackEntry?.destination?.hierarchy?.first()?.route

                        //to hide bottomNavBar
                        if (currentRoute !in items) return@Scaffold

                        BottomNavBar(
                            items = navItems,
                            navController = navController,
                            onClick = {
                                navController.navigate(it.route)
                            })

                    }
                ) {
                    StartNav(navController)
                }

            }
        }
    }
}

navigation.kt

代码语言：javascript
运行
复制
@Composable
fun StartNav(navController: NavHostController) {

    NavHost(navController = navController, startDestination = "splash_screen") {
        composable("splash_screen") {
            SplashScreen(navController)
        }
        composable("screen_1") {
            Screen1(navController)
        }
        composable("screen_2") {
            Screen2(navController)
        }

        composable("screen_3") {
            Screen3(navController)
        }
    }
}

Splashscreen.kt

代码语言：javascript
运行
复制
@Composable
fun SplashScreen(navController: NavController) {
    LaunchedEffect(key1 = true) {
        delay(2000L)
        navController.navigate("screen_1")
    }

    Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
        Text("Splash Screen")
    }
}

Screen1.kt

代码语言：javascript
运行
复制
@Composable
fun Screen1(navController: NavController) {
    Column(
        modifier = Modifier.fillMaxSize(),
        verticalArrangement = Arrangement.Center,
        horizontalAlignment = Alignment.CenterHorizontally,

        ) {
        Text("1st Screen ", fontSize = 64.sp)
    }
}

Screen2.kt

代码语言：javascript
运行
复制
@Composable
fun Screen2(navController: NavController) {
    Column(
        modifier = Modifier.fillMaxSize(),
        verticalArrangement = Arrangement.Center,
        horizontalAlignment = Alignment.CenterHorizontally,

        ) {
        Text("2nd Screen", fontSize = 64.sp,
            modifier = Modifier.clickable {
                navController.navigate("screen_3") {

                }
            })
    }
}

Screen3.kt

代码语言：javascript
运行
复制
@Composable
fun Screen3(navController: NavController) {
    Column(
        modifier = Modifier.fillMaxSize(),
        verticalArrangement = Arrangement.Center,
        horizontalAlignment = Alignment.CenterHorizontally,

        ) {
        Text("3st Screen ", fontSize = 64.sp, modifier = Modifier.clickable {
            navController.navigate("splash_screen") {
                popUpTo("splash_screen") {
                    inclusive = true
                }
            }
        })
    }
}
票数 2
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/71010271

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