我的 Fragment 中有以下方法
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
val fm = childFragmentManager
var prefsFragment: PrefsFragment? = fm.findFragmentByTag(tableName) as PrefsFragment?
if (prefsFragment == null) {
prefsFragment = PrefsFragment()
val ft = fm.beginTransaction()
ft.add(R.id.parameters_fragment_container, prefsFragment, tableName)
ft.commit()
fm.executePendingTransactions()
}
}
我不得不说这是 Java->Kotlin 自动翻译器对我以前的 Java 代码所做的(除了我通过标签找到
? 的行末尾的 PrefsFragment )，所以它可能不完全是 kosher 。我正在通过实践来学习 Kotlin。现在，当我调用
executePendingTransactions() 时，我的应用程序崩溃并抛出 java.lang.IllegalArgumentException 并显示错误消息“指定为非空的参数为空:方法 kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull，参数savedInstanceState”。现在，是的，savedInstanceState 实际上是 null，但它与显然抛出异常的调用有什么关系？我确保没有其他值/变量为空，所以我相信错误消息......但为什么呢？编辑 这是堆栈跟踪，以及让我做噩梦的源代码
https://gist.github.com/Morpheu5/8ec7e2064f53679405769b43c64f2cb7
E/AndroidRuntime: FATAL EXCEPTION: main
Process: net.morpheu5.bleedingscorecalculator, PID: 2685
java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter savedInstanceState
at net.morpheu5.bleedingscorecalculator.CalculatorScreen$PrefsFragment.onCreatePreferences(CalculatorScreen.kt:0)
at android.support.v7.preference.PreferenceFragmentCompat.onCreate(PreferenceFragmentCompat.java:223)
at android.support.v4.app.Fragment.performCreate(Fragment.java:2075)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1060)
at android.support.v4.app.BackStackRecord.setLastIn(BackStackRecord.java:838)
at android.support.v4.app.BackStackRecord.calculateFragments(BackStackRecord.java:861)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:719)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1682)
at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:594)
at net.morpheu5.bleedingscorecalculator.CalculatorScreen.onActivityCreated(CalculatorScreen.kt:34)
at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:2096)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1295)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:801)
at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:1643)
at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:679)
at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:143)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1272)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1120)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1646)
at android.view.View.measure(View.java:19857)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:703)
at android.support.design.widget.HeaderScrollingViewBehavior.onMeasureChild(HeaderScrollingViewBehavior.java:90)
at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onMeasureChild(AppBarLayout.java:1367)
at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:768)
at android.view.View.measure(View.java:19857)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
at android.view.View.measure(View.java:19857)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:758)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:640)
at android.view.View.measure(View.java:19857)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at android.view.View.measure(View.java:19857)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:758)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:640)
at android.view.View.measure(View.java:19857)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at com.android.internal.policy.DecorView.onMeasure(DecorView.java:689)
at android.view.View.measure(View.java:19857)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2275)
E/AndroidRuntime: at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1366)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1619)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1254)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6337)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:874)
at android.view.Choreographer.doCallbacks(Choreographer.java:686)
at android.view.Choreographer.doFrame(Choreographer.java:621)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:860)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
最佳答案
异常实际上并非来自该代码。它来自您的 CalculatorScreen.PrefsFragment.onCreatePreferences() 方法。如果你看那里，它看起来像——override fun onCreatePreferences(savedInstanceState: Bundle, rootKey : String)
它应该是以下内容以允许 savedInstanceState 为 null --override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey : String)
关于android - FragmentManager 在 Kotlin 中抛出 IllegalArgumentException，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/41146221/