致命异常:java.lang.NullPointerException 时使用 ViewPager

Question

我在我的应用程序中使用 ViewPager 在选项卡中显示 3 个片段。在开发人员控制台中报告以下崩溃，但没有任何指向问题的详细指针

错误：

尝试调用虚拟方法 'android.os.Handler android.support.v4.app.FragmentHostCallback.getHandler（）' on a null 对象引用

以下是崩溃细节——

Fatal Exception: java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Handler android.support.v4.app.FragmentHostCallback.getHandler()' on a null object reference
   at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:1613)
   at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:633)
   at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:143)
   at android.support.v4.view.ViewPager.populate(ViewPager.java:1177)
   at android.support.v4.view.ViewPager.populate(ViewPager.java:1025)
   at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1545)
   at android.view.View.measure(View.java:18880)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5952)
   at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:668)
   at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:735)
   at android.view.View.measure(View.java:18880)
   at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:716)
   at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:462)
   at android.view.View.measure(View.java:18880)
   at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:716)
   at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:462)
   at android.view.View.measure(View.java:18880)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5952)
   at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
   at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
   at android.view.View.measure(View.java:18880)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5952)
   at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
   at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
   at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
   at android.view.View.measure(View.java:18880)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5952)
   at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
   at android.view.View.measure(View.java:18880)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5952)
   at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
   at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
   at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
   at android.view.View.measure(View.java:18880)
   at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5952)
   at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
   at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2650)
   at android.view.View.measure(View.java:18880)
   at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2104)
   at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1220)
   at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1456)
   at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1111)
   at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6017)
   at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
   at android.view.Choreographer.doCallbacks(Choreographer.java:670)
   at android.view.Choreographer.doFrame(Choreographer.java:606)
   at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
   at android.os.Handler.handleCallback(Handler.java:739)
   at android.os.Handler.dispatchMessage(Handler.java:95)
   at android.os.Looper.loop(Looper.java:224)
   at android.app.ActivityThread.main(ActivityThread.java:5526)
   at java.lang.reflect.Method.invoke(Method.java)
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

任何人都面临类似的问题，有什么解决方案？

Answer 1

我有时也遇到过这个问题。我不知道你在这种情况下是否使用Handler（android.os.handler）。如果您正在使用，请确保已在 onCreate 上初始化它。初始化后，我已经解决了这种类型的日志猫错误