Android Studio Jetpack合成中的导航不断崩溃

flmtquvp  于 2022-11-16  发布在  Android
关注(0)|答案(1)|浏览(165)

我尝试使用Navigation从两个不同的函数访问一个带参数的函数。当我在模拟器中尝试时，应用程序崩溃。应用程序正常构建。
我使用的是compose 1.0.1和navigation 2.5.0
这是导航功能：

@Composable
fun Nav() {

    val navController = rememberNavController()

    NavHost(navController = navController, startDestination = "Main") {
        composable("Main") { Main() }
        composable("Detail/{name}") { backStackEntry ->
            Detail(backStackEntry.arguments?.getString("name").toString())
        }
        composable("Info") { Info(navController) }
        composable("Table") { Table(navController) }
    }
}

这是Main函数，在这里我使用TabRow在屏幕之间导航：

@Composable
fun Main() {
    val tabs = listOf(TabItem.Table, TabItem.Info)
    val tabNum = remember { mutableStateOf(0) }
    
    Scaffold(bottomBar = {
        TabRow(modifier = Modifier.backgroudn(Color.Gray), selectedTabIndex = tabNum.value) {
            tabs.forEachIndexed { index, tab ->
                Tab(text = { Text(tab.title) }, selected = tabNum.value == index, onClick = { tabNum.value = index })
            }
        }
    }) {
        Column(modifier = Modifier.fillMaxHeight()) {
            tabs[tabNum.value].screen()
        }
    }
}

这是TabItem密封类，用于导航：

typealias ComposableFun = @Composable () -> Unit

sealed class TabItem(var title: String, var screen: ComposableFun) {
    object Table : TabItem("Table", { Table(rememberNavController()) })
    object Info : TabItem("Info", { Info(rememberNavController()) })
}

这是Table函数的简短版本：

@Composable
fun Table(navController: NavController) {
    val elements1: List<String> = listOf("H", "Li", "Na", "K", "Rb", "Cs", "Fr")

    Column {
        elements1.forEach { i ->
            Box(modifier = Modifier.size(75.dp).padding(1.dp).clickable(onClick = {
                navController.navigate("Detail/$i")
            })) {
                Canvas(modifier = Modifier.size(75.dp), onDraw = {
                    drawRect(color = Color.Red)
                })
                Text(text = i, fontSize = 30.sp)
            }
        }
    }
}

这是Info函数：

@Composable
fun Info(navController: NavController) {

    val elements: List<String> = listOf("H", "He", "Li", "Be", "B", "C", "N", "O", "F", "Ne", "Na")

    Column {
        elements.forEach { i ->
            Box(modifier = Modifier
                .size(width = 1000.dp, height = 50.dp)
                .padding(5.dp)
                .background(Color.Red)
                .clickable(onClick = {
                    navController.navigate("Detail/$i")
                })) {
                Text(text = text i, fontSize = 30.sp)
            }
        }
    }
}

这是Detail函数的简短版本：

@Composable
fun Detail(name: String) {
    
    Column {
        Box(modifier = Modifier.size(75.dp).padding(1.dp)) {
            Canvas(modifier = Modifier.size(75.dp), onDraw = {
                drawRect(color = Color.Red)
            })
            Text(text = name, fontSize = 30.sp)
        }
    }
}

以下是崩溃日志：

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.tavolaperiodica, PID: 8360
    java.lang.NullPointerException
        at androidx.navigation.NavController.navigate(NavController.kt:1652)
        at androidx.navigation.NavController.navigate(NavController.kt:1984)
        at androidx.navigation.NavController.navigate$default(NavController.kt:1979)
        at com.example.tavolaperiodica.TableKt$Table$1$1$1$1$1$1.invoke(Table.kt:50)
        at com.example.tavolaperiodica.TableKt$Table$1$1$1$1$1$1.invoke(Table.kt:49)
        at androidx.compose.foundation.ClickableKt$clickable$4$gesture$1$2.invoke-k-4lQ0M(Clickable.kt:137)
        at androidx.compose.foundation.ClickableKt$clickable$4$gesture$1$2.invoke(Clickable.kt:137)
        at androidx.compose.foundation.gestures.TapGestureDetectorKt$detectTapAndPress$2$1$1.invokeSuspend(TapGestureDetector.kt:378)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.DispatchedTaskKt.resume(DispatchedTask.kt:178)
        at kotlinx.coroutines.DispatchedTaskKt.dispatch(DispatchedTask.kt:166)
        at kotlinx.coroutines.CancellableContinuationImpl.dispatchResume(CancellableContinuationImpl.kt:397)
        at kotlinx.coroutines.CancellableContinuationImpl.resumeImpl(CancellableContinuationImpl.kt:431)
        at kotlinx.coroutines.CancellableContinuationImpl.resumeImpl$default(CancellableContinuationImpl.kt:420)
        at kotlinx.coroutines.CancellableContinuationImpl.resumeWith(CancellableContinuationImpl.kt:328)
        at androidx.compose.ui.input.pointer.SuspendingPointerInputFilter$PointerEventHandlerCoroutine.offerPointerEvent(SuspendingPointerInputFilter.kt:432)
        at androidx.compose.ui.input.pointer.SuspendingPointerInputFilter.dispatchPointerEvent(SuspendingPointerInputFilter.kt:330)
        at androidx.compose.ui.input.pointer.SuspendingPointerInputFilter.onPointerEvent-H0pRuoY(SuspendingPointerInputFilter.kt:343)
        at androidx.compose.ui.input.pointer.Node.dispatchMainEventPass(HitPathTracker.kt:287)
        at androidx.compose.ui.input.pointer.Node.dispatchMainEventPass(HitPathTracker.kt:275)
        at androidx.compose.ui.input.pointer.Node.dispatchMainEventPass(HitPathTracker.kt:275)
        at androidx.compose.ui.input.pointer.NodeParent.dispatchMainEventPass(HitPathTracker.kt:151)
        at androidx.compose.ui.input.pointer.HitPathTracker.dispatchChanges(HitPathTracker.kt:90)
        at androidx.compose.ui.input.pointer.PointerInputEventProcessor.process-gBdvCQM(PointerInputEventProcessor.kt:77)
        at androidx.compose.ui.platform.AndroidComposeView.dispatchTouchEvent(AndroidComposeView.android.kt:860)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3030)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2719)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3030)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2719)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3030)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2719)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3030)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2719)
        at com.android.internal.policy.DecorView.superDispatchTouchEvent(DecorView.java:440)
        at com.android.internal.policy.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1830)
        at android.app.Activity.dispatchTouchEvent(Activity.java:3400)
        at com.android.internal.policy.DecorView.dispatchTouchEvent(DecorView.java:398)
        at android.view.View.dispatchPointerEvent(View.java:12752)
        at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:5106)
        at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4909)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4426)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4479)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4445)
        at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4585)
E/AndroidRuntime:     at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4453)
        at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4642)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4426)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4479)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4445)
        at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4453)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4426)
        at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:7092)
        at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:7061)
        at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:7022)
        at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:7195)
        at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:186)
        at android.os.MessageQueue.nativePollOnce(Native Method)
        at android.os.MessageQueue.next(MessageQueue.java:326)
        at android.os.Looper.loop(Looper.java:160)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
        Suppressed: kotlinx.coroutines.DiagnosticCoroutineContextException: [androidx.compose.runtime.BroadcastFrameClock@3ef7ee, StandaloneCoroutine{Cancelling}@a6e448f, AndroidUiDispatcher@f70f31c]
I/Process: Sending signal. PID: 8360 SIG: 9
android-studio

1条答案

按热度按时间
zengzsys

zengzsys1#

问题出在您的TabItem密封类别。当建立Table对象和Info对象时，它们会呼叫rememberNavController()，这会导致为您的Activity建立新的NavController执行严修。这表示您正在覆写您在Nav可组合函式中建立的NavController。
您应该遵循文档中提到的原则：
您应该在可组合层次结构中所有需要引用它的可组合对象都可以访问它的位置创建NavController。（）作为更新屏幕外的可组合对象的真实源。有关此功能的示例，请参阅与底部导航栏集成。
https://developer.android.com/jetpack/compose/navigation#getting-started

赞(0）分享  回复(0）举报  2022-11-16
我来回答

相关问题

    查看更多

    热门标签

    更多
    JavaquerypythonNode开发语言requestUtil数据库Table后端算法LoggerMessageElementParser

    最新问答

    更多
    • 蜀ICP备2022004421号-2 NULL123 https://www.null123.com © All rights reserved
    • 本站内容来源互联网,如果侵犯您的权益请联系我们删除, 联系方式：448109455@qq.com