空指针异常只发生在 KitKat 上
Null Pointer Exception only happens on KitKat
我的应用程序有一个小问题。在设置片段中，按下导航栏上的后退按钮或后退箭头将导致崩溃。这只发生在 API 19。我正在使用 Navigator 和 Settings androidX 组件。我确保我使用的是最新的一切，从 gradle 到 androidX 模块。我的最小 API 是 19，因为我希望一些旧设备可以与此应用程序一起使用。我完全不知道问题出在哪里，唯一的解决办法是忍受它（每次进入设置时重新启动应用程序）或将最小 API 级别提高到 21.
发生崩溃的一段 MainScreen 片段 [什么是 NullPointerException，我该如何解决][1] 没有帮助：
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View?
{
//crash happens here, but only when returning from settings
val view = inflater.inflate(R.layout.fragment_main_screen, container, false)
setHasOptionsMenu(true)
view.button_newEntry.setOnClickListener {
view.findNavController().navigate(R.id.action_mainScreen_to_newEntry)
}
return view
}
似乎在主屏幕视图的第二个 inflation 期间失败，不知道为什么。在较新版本上工作正常。
编辑：根据要求，mainScreen.xml我也知道 nullPointerException 是什么 [什么是 NullPointerException，我该如何修复它？][1] 没有帮助：
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Fragments.MainScreen">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ProgressBar
android:id="@+id/uploadProgressBar"
style="@style/Widget.AppCompat.ProgressBar.Horizontal"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/searchView" />
<SearchView
android:id="@+id/searchView"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/rw_items"
android:layout_width="0dp"
android:layout_height="0dp"
android:isScrollContainer="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/uploadProgressBar"
tools:listitem="@layout/item" />
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="@+id/button_newEntry"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:layout_marginBottom="16dp"
android:background="#00FFFFFF"
android:clickable="true"
android:focusable="true"
android:src="@android:drawable/ic_input_add"
android:visibility="visible"
app:backgroundTint="#3F51B5"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</FrameLayout>
完整错误信息：
Process: sk.tuke.archivator, PID: 5329
android.view.InflateException: Binary XML file line #22: Error inflating class <unknown>
at android.view.LayoutInflater.createView(LayoutInflater.java:621)
at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56)
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:670)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:695)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:756)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:759)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
at sk.tuke.archivator.Fragments.MainScreen.onCreateView(MainScreen.kt:43)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881)
at androidx.fragment.app.FragmentManagerImpl.addAddedFragments(FragmentManagerImpl.java:2100)
at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1874)
at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1830)
at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
at androidx.fragment.app.FragmentManagerImpl.run(FragmentManagerImpl.java:150)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.constructNative(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at android.view.LayoutInflater.createView(LayoutInflater.java:595)
at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56)
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:670)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:695)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:756)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:759)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
at sk.tuke.archivator.Fragments.MainScreen.onCreateView(MainScreen.kt:43)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881)
at androidx.fragment.app.FragmentManagerImpl.addAddedFragments(FragmentManagerImpl.java:2100)
at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1874)
at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1830)
at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
at androidx.fragment.app.FragmentManagerImpl.run(FragmentManagerImpl.java:150)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.widget.SearchView.onRtlPropertiesChanged(SearchView.java:1359)
at android.view.View.resolvePadding(View.java:12407)
at android.view.ViewGroup.resolvePadding(ViewGroup.java:5665)
at android.view.View.initializeScrollbars(View.java:4239)
at android.view.View.<init>(View.java:3934)
at android.view.ViewGroup.<init>(ViewGroup.java:470)
at android.widget.LinearLayout.<init>(LinearLayout.java:176)
at android.widget.LinearLayout.<init>(LinearLayout.java:172)
at android.widget.SearchView.<init>(SearchView.java:245)
at java.lang.reflect.Constructor.constructNative(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at android.view.LayoutInflater.createView(LayoutInflater.java:595)
at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56)
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:670)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:695)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:756)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:759)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
at sk.tuke.archivator.Fragments.MainScreen.onCreateView(MainScreen.kt:43)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881)
at androidx.fragment.app.FragmentManagerImpl.addAddedFragments(FragmentManagerImpl.java:2100)
at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1874)
at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1830)
at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
at androidx.fragment.app.FragmentManagerImpl.run(FragmentManagerImpl.java:150)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method) ```
[1]:
感谢 @LenaBru I managed to find out that the searchView was causing the crash. After quite some trial and error replacing searchView with androidx.appcompat.widget.SearchView 解决了这个问题。谢谢大家的帮助。
您的应用在 XML 上 line #22
问题是它找不到您的 SearchView
如果您将其注释掉或替换为其他内容，它应该可以工作。
我的应用程序有一个小问题。在设置片段中，按下导航栏上的后退按钮或后退箭头将导致崩溃。这只发生在 API 19。我正在使用 Navigator 和 Settings androidX 组件。我确保我使用的是最新的一切，从 gradle 到 androidX 模块。我的最小 API 是 19，因为我希望一些旧设备可以与此应用程序一起使用。我完全不知道问题出在哪里，唯一的解决办法是忍受它（每次进入设置时重新启动应用程序）或将最小 API 级别提高到 21.
发生崩溃的一段 MainScreen 片段 [什么是 NullPointerException，我该如何解决][1] 没有帮助：
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View?
{
//crash happens here, but only when returning from settings
val view = inflater.inflate(R.layout.fragment_main_screen, container, false)
setHasOptionsMenu(true)
view.button_newEntry.setOnClickListener {
view.findNavController().navigate(R.id.action_mainScreen_to_newEntry)
}
return view
}
似乎在主屏幕视图的第二个 inflation 期间失败，不知道为什么。在较新版本上工作正常。
编辑：根据要求，mainScreen.xml我也知道 nullPointerException 是什么 [什么是 NullPointerException，我该如何修复它？][1] 没有帮助：
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Fragments.MainScreen">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ProgressBar
android:id="@+id/uploadProgressBar"
style="@style/Widget.AppCompat.ProgressBar.Horizontal"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/searchView" />
<SearchView
android:id="@+id/searchView"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/rw_items"
android:layout_width="0dp"
android:layout_height="0dp"
android:isScrollContainer="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/uploadProgressBar"
tools:listitem="@layout/item" />
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="@+id/button_newEntry"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:layout_marginBottom="16dp"
android:background="#00FFFFFF"
android:clickable="true"
android:focusable="true"
android:src="@android:drawable/ic_input_add"
android:visibility="visible"
app:backgroundTint="#3F51B5"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</FrameLayout>
完整错误信息：
Process: sk.tuke.archivator, PID: 5329
android.view.InflateException: Binary XML file line #22: Error inflating class <unknown>
at android.view.LayoutInflater.createView(LayoutInflater.java:621)
at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56)
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:670)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:695)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:756)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:759)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
at sk.tuke.archivator.Fragments.MainScreen.onCreateView(MainScreen.kt:43)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881)
at androidx.fragment.app.FragmentManagerImpl.addAddedFragments(FragmentManagerImpl.java:2100)
at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1874)
at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1830)
at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
at androidx.fragment.app.FragmentManagerImpl.run(FragmentManagerImpl.java:150)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.constructNative(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at android.view.LayoutInflater.createView(LayoutInflater.java:595)
at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56)
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:670)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:695)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:756)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:759)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
at sk.tuke.archivator.Fragments.MainScreen.onCreateView(MainScreen.kt:43)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881)
at androidx.fragment.app.FragmentManagerImpl.addAddedFragments(FragmentManagerImpl.java:2100)
at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1874)
at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1830)
at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
at androidx.fragment.app.FragmentManagerImpl.run(FragmentManagerImpl.java:150)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.widget.SearchView.onRtlPropertiesChanged(SearchView.java:1359)
at android.view.View.resolvePadding(View.java:12407)
at android.view.ViewGroup.resolvePadding(ViewGroup.java:5665)
at android.view.View.initializeScrollbars(View.java:4239)
at android.view.View.<init>(View.java:3934)
at android.view.ViewGroup.<init>(ViewGroup.java:470)
at android.widget.LinearLayout.<init>(LinearLayout.java:176)
at android.widget.LinearLayout.<init>(LinearLayout.java:172)
at android.widget.SearchView.<init>(SearchView.java:245)
at java.lang.reflect.Constructor.constructNative(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at android.view.LayoutInflater.createView(LayoutInflater.java:595)
at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56)
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:670)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:695)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:756)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:759)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
at sk.tuke.archivator.Fragments.MainScreen.onCreateView(MainScreen.kt:43)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881)
at androidx.fragment.app.FragmentManagerImpl.addAddedFragments(FragmentManagerImpl.java:2100)
at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1874)
at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1830)
at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
at androidx.fragment.app.FragmentManagerImpl.run(FragmentManagerImpl.java:150)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method) ```
[1]:
感谢 @LenaBru I managed to find out that the searchView was causing the crash. After quite some trial and error replacing searchView with androidx.appcompat.widget.SearchView 解决了这个问题。谢谢大家的帮助。
您的应用在 XML 上 line #22
问题是它找不到您的 SearchView
如果您将其注释掉或替换为其他内容，它应该可以工作。