Android Navcontroller 硬件后退按钮崩溃

【问题标题】：Android Navcontroller hardware back button crashAndroid Navcontroller 硬件后退按钮崩溃
【发布时间】：2019-04-25 11:29:07
【问题描述】：

我正在使用新的 android 故事板来创建应用程序。流程需要如下所示：

SplashFragment -> Fragment1 -> Fragment2

下面是故事板(navigation_main.xml)：

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:app="http://schemas.android.com/apk/res-auto"
            xmlns:tools="http://schemas.android.com/tools" android:id="@+id/launch_navigation_graph"
            app:startDestination="@id/splashFragment">

    <fragment android:id="@+id/splashFragment" android:name="com.myapp.android.SplashFragment"
              android:label="fragment_splash" tools:layout="@layout/fragment_splash">
        <action android:id="@+id/action_splashFragment_to_fragment1"
                app:destination="@id/fragment1"/>
    </fragment>
    <fragment android:id="@+id/fragment1"
              android:name="com.myapp.android.Fragment1"
              android:label="fragment1" tools:layout="@layout/fragment_register_msisdn">
        <action android:id="@+id/action_fragment1_to_fragment2"
                app:destination="@id/fragment2" app:popUpTo="@+id/fragment1"
                app:enterAnim="@anim/nav_default_pop_enter_anim" app:exitAnim="@anim/nav_default_pop_exit_anim"/>
    </fragment>
    <fragment android:id="@+id/fragment2"
              android:name="com.myapp.android.Fragment2"
              android:label="fragment_fragment2" tools:layout="@layout/fragment_fragment2"/>
</navigation>

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context="MainActivity">

    <fragment
            android:id="@+id/mainNavigationHostFragment"
            android:name="androidx.navigation.fragment.NavHostFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:defaultNavHost="true"
            app:navGraph="@navigation/navigation_main" />

</androidx.constraintlayout.widget.ConstraintLayout>

应用主题没有操作栏，因为我不想显示操作栏：

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">

基本上我需要Fragment1 到Fragment2 导航，然后按下硬件返回按钮，返回Fragment1。要从 Fragment1 导航到 Fragment2，我在 Fragment1 中有以下代码：

findNavController().navigate(R.id.action_fragment1_to_fragment2)

SplashFragment 不应保留在堆栈中，因为在启动时首次显示后不需要它。这就是为什么我只有在Fragment1 到Fragment2 行动中才有popTo。但是在运行相同的程序后，从Fragment2 按下返回，第一次什么都不做（不弹出），第二次，它崩溃并出现以下异常：

2019-04-25 16:52:43.841 28598-28598/com.selfcare.safaricom E/InputEventSender: Exception dispatching finished signal.
2019-04-25 16:52:43.842 28598-28598/com.selfcare.safaricom E/MessageQueue-JNI: Exception in MessageQueue callback: handleReceiveCallback
2019-04-25 16:52:43.846 28598-28598/com.selfcare.safaricom E/MessageQueue-JNI: java.lang.IllegalArgumentException: navigation destination com.selfcare.safaricom:id/action_splashFragment_to_registerMSISDNFragment is unknown to this NavController
        at androidx.navigation.NavController.navigate(NavController.java:803)
        at androidx.navigation.NavController.navigate(NavController.java:744)
        at androidx.navigation.NavController.navigate(NavController.java:730)
        at androidx.navigation.NavController.navigate(NavController.java:718)
        at com.myapp.android.SplashFragment.handleLaunchStatus(SplashFragment.kt:51)
        at com.myapp.android.SplashFragment.access$handleLaunchStatus(SplashFragment.kt:16)
        at com.myapp.android.SplashFragment$attachLaunchObserver$1.onChanged(SplashFragment.kt:44)
        at com.myapp.android.SplashFragment$attachLaunchObserver$1.onChanged(SplashFragment.kt:16)
        at androidx.lifecycle.LiveData.considerNotify(LiveData.java:113)
        at androidx.lifecycle.LiveData.dispatchingValue(LiveData.java:126)
        at androidx.lifecycle.LiveData$ObserverWrapper.activeStateChanged(LiveData.java:424)
        at androidx.lifecycle.LiveData$LifecycleBoundObserver.onStateChanged(LiveData.java:376)
        at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.java:361)
        at androidx.lifecycle.LifecycleRegistry.addObserver(LifecycleRegistry.java:188)
        at androidx.lifecycle.LiveData.observe(LiveData.java:185)
        at com.myapp.android.SplashFragment.attachLaunchObserver(SplashFragment.kt:43)
        at com.myapp.android.SplashFragment.onViewCreated(SplashFragment.kt:35)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:895)
        at androidx.fragment.app.FragmentManagerImpl.addAddedFragments(FragmentManagerImpl.java:2092)
        at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1866)
        at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1822)
        at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManagerImpl.java:298)
        at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManagerImpl.java:241)
        at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManagerImpl.java:288)
        at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManagerImpl.java:241)
        at androidx.fragment.app.FragmentActivity$1.handleOnBackPressed(FragmentActivity.java:144)
        at androidx.activity.OnBackPressedDispatcher.onBackPressed(OnBackPressedDispatcher.java:136)
        at androidx.activity.ComponentActivity.onBackPressed(ComponentActivity.java:283)
        at android.app.Activity.onKeyUp(Activity.java:3083)
        at android.view.KeyEvent.dispatch(KeyEvent.java:2716)
        at android.app.Activity.dispatchKeyEvent(Activity.java:3366)
        at androidx.core.app.ComponentActivity.superDispatchKeyEvent(ComponentActivity.java:80)
        at androidx.core.view.KeyEventDispatcher.dispatchKeyEvent(KeyEventDispatcher.java:84)
        at androidx.core.app.ComponentActivity.dispatchKeyEvent(ComponentActivity.java:98)
        at androidx.appcompat.app.AppCompatActivity.dispatchKeyEvent(AppCompatActivity.java:558)
        at androidx.appcompat.view.WindowCallbackWrapper.dispatchKeyEvent(WindowCallbackWrapper.java:59)
        at androidx.appcompat.app.AppCompatDelegateImpl$AppCompatWindowCallback.dispatchKeyEvent(AppCompatDelegateImpl.java:2736)
        at com.android.internal.policy.DecorView.dispatchKeyEvent(DecorView.java:342)
        at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:5037)
        at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4905)
        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)
        at android.view.ViewRootImpl$InputStage.apply(Vie
2019-04-25 16:52:43.849 28598-28598/com.selfcare.safaricom E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.selfcare.safaricom, PID: 28598
    java.lang.IllegalArgumentException: navigation destination com.selfcare.safaricom:id/action_splashFragment_to_registerMSISDNFragment is unknown to this NavController
        at androidx.navigation.NavController.navigate(NavController.java:803)
        at androidx.navigation.NavController.navigate(NavController.java:744)
        at androidx.navigation.NavController.navigate(NavController.java:730)
        at androidx.navigation.NavController.navigate(NavController.java:718)
        at com.myapp.android.SplashFragment.handleLaunchStatus(SplashFragment.kt:51)
        at com.myapp.android.SplashFragment.access$handleLaunchStatus(SplashFragment.kt:16)
        at com.myapp.android.SplashFragment$attachLaunchObserver$1.onChanged(SplashFragment.kt:44)
        at com.myapp.android.SplashFragment$attachLaunchObserver$1.onChanged(SplashFragment.kt:16)
        at androidx.lifecycle.LiveData.considerNotify(LiveData.java:113)
        at androidx.lifecycle.LiveData.dispatchingValue(LiveData.java:126)
        at androidx.lifecycle.LiveData$ObserverWrapper.activeStateChanged(LiveData.java:424)
        at androidx.lifecycle.LiveData$LifecycleBoundObserver.onStateChanged(LiveData.java:376)
        at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.java:361)
        at androidx.lifecycle.LifecycleRegistry.addObserver(LifecycleRegistry.java:188)
        at androidx.lifecycle.LiveData.observe(LiveData.java:185)
        at com.myapp.android.SplashFragment.attachLaunchObserver(SplashFragment.kt:43)
        at com.myapp.android.SplashFragment.onViewCreated(SplashFragment.kt:35)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:895)
        at androidx.fragment.app.FragmentManagerImpl.addAddedFragments(FragmentManagerImpl.java:2092)
        at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1866)
        at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1822)
        at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManagerImpl.java:298)
        at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManagerImpl.java:241)
        at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManagerImpl.java:288)
        at androidx.fragment.app.FragmentManagerImpl.popBackStackImmediate(FragmentManagerImpl.java:241)
        at androidx.fragment.app.FragmentActivity$1.handleOnBackPressed(FragmentActivity.java:144)
        at androidx.activity.OnBackPressedDispatcher.onBackPressed(OnBackPressedDispatcher.java:136)
        at androidx.activity.ComponentActivity.onBackPressed(ComponentActivity.java:283)
        at android.app.Activity.onKeyUp(Activity.java:3083)
        at android.view.KeyEvent.dispatch(KeyEvent.java:2716)
        at android.app.Activity.dispatchKeyEvent(Activity.java:3366)
        at androidx.core.app.ComponentActivity.superDispatchKeyEvent(ComponentActivity.java:80)
        at androidx.core.view.KeyEventDispatcher.dispatchKeyEvent(KeyEventDispatcher.java:84)
        at androidx.core.app.ComponentActivity.dispatchKeyEvent(ComponentActivity.java:98)
        at androidx.appcompat.app.AppCompatActivity.dispatchKeyEvent(AppCompatActivity.java:558)
        at androidx.appcompat.view.WindowCallbackWrapper.dispatchKeyEvent(WindowCallbackWrapper.java:59)
        at androidx.appcompat.app.AppCompatDelegateImpl$AppCompatWindowCallback.dispatchKeyEvent(AppCompatDelegateImpl.java:2736)
        at com.android.internal.policy.DecorView.dispatchKeyEvent(DecorView.java:342)
        at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:5037)
        at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4905)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4426)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4479)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4445)
2019-04-25 16:52:43.851 28598-28598/com.selfcare.safaricom E/AndroidRuntime:     at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4585)
        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$InputStage.deliver(ViewRootImpl.java:4426)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4479)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4445)
        at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4618)
        at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:4779)
        at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:2571)
        at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:2081)
        at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:2072)
        at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:2548)
        at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141)
        at android.os.MessageQueue.nativePollOnce(Native Method)
        at android.os.MessageQueue.next(MessageQueue.java:326)
        at android.os.Looper.loop(Looper.java:160)
        at android.app.ActivityThread.main(ActivityThread.java:6718)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

SplashFragment 第 51 行是：

findNavController().navigate(R.id.action_splashFragment_to_fragment1)

如果我将 popTo 从 Fragment1 删除到 Fragment2 操作，则此异常消失，但后退按钮也不起作用。我在这里做错了什么？

编辑 1：

根据 Stavro Xhardha 的评论，我对导航 XML 进行了一些修改：

<fragment android:id="@+id/splashFragment" android:name="com.myapp.android.SplashFragment"
          android:label="fragment_splash" tools:layout="@layout/fragment_splash">
    <action android:id="@+id/action_splashFragment_to_fragment1"
            app:destination="@id/fragment1"
    app:popUpToInclusive="true" app:popUpTo="@+id/splashFragment"/> <!--Added this line -->
</fragment>
<fragment android:id="@+id/fragment1"
          android:name="com.myapp.android.Fragment1"
          android:label="fragment1" tools:layout="@layout/fragment_register_msisdn">
    <action android:id="@+id/action_fragment1_to_fragment2"
            app:destination="@id/fragment2" app:popUpTo="@+id/fragment1"/>
</fragment>
<fragment android:id="@+id/fragment2"
          android:name="com.myapp.android.Fragment2"
          android:label="fragment_fragment2" tools:layout="@layout/fragment_fragment2"/>

并在MainActivity 中覆盖 onBackPressed 如下：

override fun onBackPressed() {
    super.onBackPressed()
    if (!findNavController(R.id.launchNavigationHostFragment).navigateUp()) {
        finish()
    }
}

现在Fragment2 弹出到Fragment1，但随后在Fragment1 上的后按继续使Fragment1 循环。我无法退出应用程序。

【问题讨论】：

  • 好吧，我真的不知道答案，但也许我可以通过此链接为您提供帮助 proandroiddev.com/…
  • 那也行不通。后退导航仍然无法正常工作。不过，在飞溅中包含弹出动作后，崩溃就消失了。但是 Fragment2 还没有弹出到 Fragment1
  • 您是否覆盖了活动中的OnSupportNavigateUp()？
  • 是的，但它没有被调用。
  • 好的，您的第一条评论实际上适用于一个小的修改不活动代码，但仍然存在一个问题。我会更新问题。

标签： android android-jetpack android-jetpack-navigation


【解决方案1】：

我终于设法找出问题并解决了它。

问题是，我从ViewModel 观察到MutableLiveData，并根据它的值进行导航。但我不知道片段的生命周期所有者倾向于破坏观察者并根据视图生命周期重新实例化它以避免泄漏。因此，一旦导航发生，观察者就不再存在，导航代码在观察者之内。导航返回时需要相同的代码，因此当尝试访问它时，代码会崩溃。

当需要导航时，我通过使用接口给片段回调来解决了这个问题。

【讨论】：

  • 是的！如果我们在实时数据回调中导航，那么您是正确的
  • 你的解决方案是什么样的
  • 是一个简单的接口回调。 Fragment 使用接口充当 ViewModel 的侦听器。 ViewModel调用接口方法时，在fragment中调用，导航发生在fragment中。
【解决方案2】：

您的错误日志显示您正在使用 navcontroller 调用操作，操作 ID 为 action_splashFragment_to_registerMSISDNFragment。尝试找到该操作 ID 并检查它是否有效。在action_splashFragment_to_fragment1 中也使用app:popUpTo="@id/splashFragment" app:popUpToInclusive="true" 而不是action_fragment1_to_fragment2。这将从后台堆栈中删除飞溅片段。这是代码sn-p：

<?xml version="1.0" encoding="utf-8"?>
    <navigation xmlns:android="http://schemas.android.com/apk/res/android"
                xmlns:app="http://schemas.android.com/apk/res-auto"
                xmlns:tools="http://schemas.android.com/tools" android:id="@+id/launch_navigation_graph"
                app:startDestination="@id/splashFragment">

        <fragment android:id="@+id/splashFragment" android:name="com.myapp.android.SplashFragment"
                  android:label="fragment_splash" tools:layout="@layout/fragment_splash">
            <action android:id="@+id/action_splashFragment_to_fragment1"
                    app:destination="@id/fragment1"
                app:popUpTo="@id/splashFragment"
                app:popUpToInclusive="true" />
        </fragment>
        <fragment android:id="@+id/fragment1"
                  android:name="com.myapp.android.Fragment1"
                  android:label="fragment1" tools:layout="@layout/fragment_register_msisdn">
            <action android:id="@+id/action_fragment1_to_fragment2"
                    app:destination="@id/fragment2"
                    app:enterAnim="@anim/nav_default_pop_enter_anim" app:exitAnim="@anim/nav_default_pop_exit_anim"/>
        </fragment>
        <fragment android:id="@+id/fragment2"
                  android:name="com.myapp.android.Fragment2"
                  android:label="fragment_fragment2" tools:layout="@layout/fragment_fragment2"/>
    </navigation>

【讨论】：

  • 这在实现 onBackPressed 后很有帮助，但我仍然遇到 Edit1 下提到的问题
  • 您不需要覆盖 onBackPressed。还可以尝试从操作 action_fragment1_to_fragment2 中删除 app:popUpTo="@+id/fragment1"。
【解决方案3】：

导航到新片段后，我刚刚删除了观察者。像这样：

myLiveData.removeObservers(this)

【讨论】：

    猜你喜欢
    • 1970-01-01
    • 1970-01-01
    • 1970-01-01
    • 1970-01-01
    • 2011-04-02
    • 1970-01-01
    • 2019-02-03
    • 1970-01-01
    相关资源
    最近更新 更多
    热门标签
    Java Python linux javascript Mysql C# Docker 算法 前端 SpringBoot Redis Vue spring 设计模式 .net core .net kubernetes c++ 数据库 数据结构 大数据 js 机器学习 微服务 Android Go 程序员 面试 JVM ASP.net core 云原生 人工智能 后端 PHP git CSS golang k8s Nginx Django mybatis 深度学习 多线程 React 架构 devops 爬虫 云计算 Spring Boot LeetCode