多个异常：无法启动 activity、无法实例化片段、膨胀错误 class
Multiple exceptions: Unable to start activity, Unable to instantiate fragment, Error inflating class
我是 Kotlin 的新手，我正在学习教程。 运行 我的应用导致它在 运行 时崩溃。我在底部导航栏应用程序中有三个片段和一个主要片段 activity。我的目标实际上只是 运行 应用成功，这样我就可以尝试 Room 数据库、数据绑定和此类概念。我搜索了它对我不起作用但没有运气的可能原因。这是当前的完整错误消息：
2021-02-27 14:58:23.967 23883-23883/com.jwanhsulaiman.talktag E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.jwanhsulaiman.talktag, PID: 23883
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.jwanhsulaiman.talktag/com.jwanhsulaiman.talktag.MainActivity}: android.view.InflateException: Binary XML file line #21: Binary XML file line #21: Error inflating class androidx.fragment.app.FragmentContainerView
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2919)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3054)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1814)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:280)
at android.app.ActivityThread.main(ActivityThread.java:6706)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: android.view.InflateException: Binary XML file line #21: Binary XML file line #21: Error inflating class androidx.fragment.app.FragmentContainerView
Caused by: android.view.InflateException: Binary XML file line #21: Error inflating class androidx.fragment.app.FragmentContainerView
Caused by: androidx.fragment.app.Fragment$InstantiationException: Unable to instantiate fragment com.jwanhsulaiman.talktag.ui.home.HomeFragment: could not find Fragment constructor
at androidx.fragment.app.Fragment.instantiate(Fragment.java:625)
at androidx.fragment.app.FragmentContainer.instantiate(FragmentContainer.java:57)
at androidx.fragment.app.FragmentManager.instantiate(FragmentManager.java:483)
at androidx.navigation.fragment.FragmentNavigator.instantiateFragment(FragmentNavigator.java:132)
at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.java:162)
at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.java:58)
at androidx.navigation.NavGraphNavigator.navigate(NavGraphNavigator.java:71)
at androidx.navigation.NavGraphNavigator.navigate(NavGraphNavigator.java:28)
at androidx.navigation.NavController.navigate(NavController.java:1059)
at androidx.navigation.NavController.onGraphCreated(NavController.java:639)
at androidx.navigation.NavController.setGraph(NavController.java:592)
at androidx.navigation.NavController.setGraph(NavController.java:557)
at androidx.navigation.NavController.setGraph(NavController.java:539)
at androidx.navigation.fragment.NavHostFragment.onCreate(NavHostFragment.java:248)
at androidx.fragment.app.Fragment.performCreate(Fragment.java:2936)
at androidx.fragment.app.FragmentStateManager.create(FragmentStateManager.java:472)
at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:278)
at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:2177)
at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:2094)
at androidx.fragment.app.FragmentManager.execSingleAction(FragmentManager.java:1959)
at androidx.fragment.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:311)
at androidx.fragment.app.FragmentContainerView.<init>(FragmentContainerView.java:176)
at androidx.fragment.app.FragmentLayoutInflaterFactory.onCreateView(FragmentLayoutInflaterFactory.java:52)
at androidx.fragment.app.FragmentController.onCreateView(FragmentController.java:135)
at androidx.fragment.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:313)
at androidx.fragment.app.FragmentActivity.onCreateView(FragmentActivity.java:292)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:780)
2021-02-27 14:58:23.971 23883-23883/com.jwanhsulaiman.talktag E/AndroidRuntime: at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:863)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:824)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:696)
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:170)
at com.jwanhsulaiman.talktag.MainActivity.onCreate(MainActivity.kt:15)
at android.app.Activity.performCreate(Activity.java:7136)
at android.app.Activity.performCreate(Activity.java:7127)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1272)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2899)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3054)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1814)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:280)
at android.app.ActivityThread.main(ActivityThread.java:6706)
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)
Caused by: java.lang.NoSuchMethodException: <init> []
at java.lang.Class.getConstructor0(Class.java:2327)
at java.lang.Class.getConstructor(Class.java:1725)
at androidx.fragment.app.Fragment.instantiate(Fragment.java:610)
... 50 more
我尝试将第 21 行的 XML 文件（根据错误）从 fragment 更改为 androidx.fragment.app.FragmentContainerView（根据 Android Studio 在悬停时的建议用鼠标。我试过添加依赖项，但似乎没有任何改善。我将提供我的代码的样子。
MainActivity.kt（错误说它在 setContentView(R.layout.activity_main) 上崩溃）
package com.jwanhsulaiman.talktag
import android.os.Bundle
import com.google.android.material.bottomnavigation.BottomNavigationView
import androidx.appcompat.app.AppCompatActivity
import androidx.navigation.findNavController
import androidx.navigation.ui.AppBarConfiguration
import androidx.navigation.ui.setupActionBarWithNavController
import androidx.navigation.ui.setupWithNavController
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val navView: BottomNavigationView = findViewById(R.id.nav_view)
val navController = findNavController(R.id.nav_host_fragment)
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
val appBarConfiguration = AppBarConfiguration(setOf(
R.id.navigation_home, R.id.navigation_dashboard, R.id.navigation_notifications))
setupActionBarWithNavController(navController, appBarConfiguration)
navView.setupWithNavController(navController)
}
}
activity_main.xml
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingTop="?attr/actionBarSize">
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/nav_view"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="0dp"
android:layout_marginEnd="0dp"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="@menu/bottom_nav_menu" />
<androidx.fragment.app.FragmentContainerView
android:id="@+id/nav_host_fragment"
class = "androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:layout_constraintBottom_toTopOf="@id/nav_view"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="@navigation/mobile_navigation" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
以及 HomeFragment 的完整片段以防相关
package com.jwanhsulaiman.talktag.ui.home
import android.content.Context
import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.databinding.DataBindingUtil
import androidx.fragment.app.Fragment
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import com.jwanhsulaiman.talktag.R
import com.jwanhsulaiman.talktag.database.VocabData
import com.jwanhsulaiman.talktag.database.VocabRepository
import com.jwanhsulaiman.talktag.databinding.FragmentHomeBinding
class HomeFragment(val applicationContext: Context) : Fragment() {
private lateinit var homeViewModel: HomeViewModel
private lateinit var binding: FragmentHomeBinding
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
homeViewModel =
ViewModelProvider(this).get(HomeViewModel::class.java)
val root = inflater.inflate(R.layout.fragment_home, container, false)
val textView: TextView = root.findViewById(R.id.text_home)
homeViewModel.text.observe(viewLifecycleOwner, Observer {
textView.text = it
})
binding = DataBindingUtil.inflate(inflater, R.layout.fragment_home, container, false)
val dao = VocabData.getInstance(this).VocabDao
val repository = VocabRepository(dao)
val factory = HomeViewModelFactory(repository)
homeViewModel = ViewModelProvider(this, factory).get(HomeViewModel::class.java)
binding.myViewModel = homeViewModel
binding.lifecycleOwner = this
displayVocabList()
return binding.root
}
private fun displayVocabList() {
homeViewModel.vocabs.observe(viewLifecycleOwner, Observer {
Log.i("MYTAG", it.toString())
})
}
}
感谢您的任何见解！
Caused by: java.lang.NoSuchMethodException: <init> []
从 HomeFragment 中删除构造函数，原因有二：
它不会工作，因为片段系统需要一个 public 零参数构造函数
您不需要传入 Context，因为一旦您的片段附加到 activity，您就可以调用 requireContext() 来检索 Context 来使用（如果你真的需要 Application 可以参考 applicationContext）
我是 Kotlin 的新手，我正在学习教程。 运行 我的应用导致它在 运行 时崩溃。我在底部导航栏应用程序中有三个片段和一个主要片段 activity。我的目标实际上只是 运行 应用成功，这样我就可以尝试 Room 数据库、数据绑定和此类概念。我搜索了它对我不起作用但没有运气的可能原因。这是当前的完整错误消息：
2021-02-27 14:58:23.967 23883-23883/com.jwanhsulaiman.talktag E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.jwanhsulaiman.talktag, PID: 23883
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.jwanhsulaiman.talktag/com.jwanhsulaiman.talktag.MainActivity}: android.view.InflateException: Binary XML file line #21: Binary XML file line #21: Error inflating class androidx.fragment.app.FragmentContainerView
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2919)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3054)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1814)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:280)
at android.app.ActivityThread.main(ActivityThread.java:6706)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: android.view.InflateException: Binary XML file line #21: Binary XML file line #21: Error inflating class androidx.fragment.app.FragmentContainerView
Caused by: android.view.InflateException: Binary XML file line #21: Error inflating class androidx.fragment.app.FragmentContainerView
Caused by: androidx.fragment.app.Fragment$InstantiationException: Unable to instantiate fragment com.jwanhsulaiman.talktag.ui.home.HomeFragment: could not find Fragment constructor
at androidx.fragment.app.Fragment.instantiate(Fragment.java:625)
at androidx.fragment.app.FragmentContainer.instantiate(FragmentContainer.java:57)
at androidx.fragment.app.FragmentManager.instantiate(FragmentManager.java:483)
at androidx.navigation.fragment.FragmentNavigator.instantiateFragment(FragmentNavigator.java:132)
at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.java:162)
at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.java:58)
at androidx.navigation.NavGraphNavigator.navigate(NavGraphNavigator.java:71)
at androidx.navigation.NavGraphNavigator.navigate(NavGraphNavigator.java:28)
at androidx.navigation.NavController.navigate(NavController.java:1059)
at androidx.navigation.NavController.onGraphCreated(NavController.java:639)
at androidx.navigation.NavController.setGraph(NavController.java:592)
at androidx.navigation.NavController.setGraph(NavController.java:557)
at androidx.navigation.NavController.setGraph(NavController.java:539)
at androidx.navigation.fragment.NavHostFragment.onCreate(NavHostFragment.java:248)
at androidx.fragment.app.Fragment.performCreate(Fragment.java:2936)
at androidx.fragment.app.FragmentStateManager.create(FragmentStateManager.java:472)
at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:278)
at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:2177)
at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:2094)
at androidx.fragment.app.FragmentManager.execSingleAction(FragmentManager.java:1959)
at androidx.fragment.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:311)
at androidx.fragment.app.FragmentContainerView.<init>(FragmentContainerView.java:176)
at androidx.fragment.app.FragmentLayoutInflaterFactory.onCreateView(FragmentLayoutInflaterFactory.java:52)
at androidx.fragment.app.FragmentController.onCreateView(FragmentController.java:135)
at androidx.fragment.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:313)
at androidx.fragment.app.FragmentActivity.onCreateView(FragmentActivity.java:292)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:780)
2021-02-27 14:58:23.971 23883-23883/com.jwanhsulaiman.talktag E/AndroidRuntime: at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:863)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:824)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:696)
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:170)
at com.jwanhsulaiman.talktag.MainActivity.onCreate(MainActivity.kt:15)
at android.app.Activity.performCreate(Activity.java:7136)
at android.app.Activity.performCreate(Activity.java:7127)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1272)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2899)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3054)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1814)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:280)
at android.app.ActivityThread.main(ActivityThread.java:6706)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.NoSuchMethodException: <init> []
at java.lang.Class.getConstructor0(Class.java:2327)
at java.lang.Class.getConstructor(Class.java:1725)
at androidx.fragment.app.Fragment.instantiate(Fragment.java:610)
... 50 more
我尝试将第 21 行的 XML 文件（根据错误）从 fragment 更改为 androidx.fragment.app.FragmentContainerView（根据 Android Studio 在悬停时的建议用鼠标。我试过添加依赖项，但似乎没有任何改善。我将提供我的代码的样子。
MainActivity.kt（错误说它在 setContentView(R.layout.activity_main) 上崩溃）
package com.jwanhsulaiman.talktag
import android.os.Bundle
import com.google.android.material.bottomnavigation.BottomNavigationView
import androidx.appcompat.app.AppCompatActivity
import androidx.navigation.findNavController
import androidx.navigation.ui.AppBarConfiguration
import androidx.navigation.ui.setupActionBarWithNavController
import androidx.navigation.ui.setupWithNavController
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val navView: BottomNavigationView = findViewById(R.id.nav_view)
val navController = findNavController(R.id.nav_host_fragment)
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
val appBarConfiguration = AppBarConfiguration(setOf(
R.id.navigation_home, R.id.navigation_dashboard, R.id.navigation_notifications))
setupActionBarWithNavController(navController, appBarConfiguration)
navView.setupWithNavController(navController)
}
}
activity_main.xml
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingTop="?attr/actionBarSize">
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/nav_view"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="0dp"
android:layout_marginEnd="0dp"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="@menu/bottom_nav_menu" />
<androidx.fragment.app.FragmentContainerView
android:id="@+id/nav_host_fragment"
class = "androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:layout_constraintBottom_toTopOf="@id/nav_view"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="@navigation/mobile_navigation" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
以及 HomeFragment 的完整片段以防相关
package com.jwanhsulaiman.talktag.ui.home
import android.content.Context
import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.databinding.DataBindingUtil
import androidx.fragment.app.Fragment
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import com.jwanhsulaiman.talktag.R
import com.jwanhsulaiman.talktag.database.VocabData
import com.jwanhsulaiman.talktag.database.VocabRepository
import com.jwanhsulaiman.talktag.databinding.FragmentHomeBinding
class HomeFragment(val applicationContext: Context) : Fragment() {
private lateinit var homeViewModel: HomeViewModel
private lateinit var binding: FragmentHomeBinding
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
homeViewModel =
ViewModelProvider(this).get(HomeViewModel::class.java)
val root = inflater.inflate(R.layout.fragment_home, container, false)
val textView: TextView = root.findViewById(R.id.text_home)
homeViewModel.text.observe(viewLifecycleOwner, Observer {
textView.text = it
})
binding = DataBindingUtil.inflate(inflater, R.layout.fragment_home, container, false)
val dao = VocabData.getInstance(this).VocabDao
val repository = VocabRepository(dao)
val factory = HomeViewModelFactory(repository)
homeViewModel = ViewModelProvider(this, factory).get(HomeViewModel::class.java)
binding.myViewModel = homeViewModel
binding.lifecycleOwner = this
displayVocabList()
return binding.root
}
private fun displayVocabList() {
homeViewModel.vocabs.observe(viewLifecycleOwner, Observer {
Log.i("MYTAG", it.toString())
})
}
}
感谢您的任何见解！
Caused by: java.lang.NoSuchMethodException: <init> []
从 HomeFragment 中删除构造函数，原因有二：
它不会工作，因为片段系统需要一个 public 零参数构造函数
您不需要传入
Context，因为一旦您的片段附加到 activity，您就可以调用requireContext()来检索Context来使用（如果你真的需要Application可以参考applicationContext）