恢复带有WebView的Fragment时，ViewPager会崩溃

Question

这是我的视图层次结构：

• codinatorlayout
  • appbarlayout
  • ViewPager
    • 4片

第一个片段具有WebView(根为WebView(。

当页面之间真正快速上映时，我最终会遇到此错误(随机发生，或在某个我不知道的地方发生(，从具有WebView或朝向它的片段中掠过。p>如果我在不包含WebViews的片段之间滑动，无论我刷过多快或多少次，它都可以正常工作。

stacktrace：

java.lang.IndexOutOfBoundsException: getChildDrawingOrder() returned invalid index 1 (child count is 1)
    at android.view.ViewGroup.getAndVerifyPreorderedIndex(ViewGroup.java:2055)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4190)
    at android.view.View.draw(View.java:21956)
    at android.view.View.updateDisplayListIfDirty(View.java:20830)
    at android.view.View.draw(View.java:21685)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4432)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4193)
    at android.view.View.updateDisplayListIfDirty(View.java:20821)
    at android.view.View.draw(View.java:21685)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4432)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4193)
    at android.view.View.updateDisplayListIfDirty(View.java:20821)
    at android.view.View.draw(View.java:21685)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4432)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4217)
    at android.view.View.draw(View.java:21956)
    at androidx.viewpager.widget.ViewPager.draw(ViewPager.java:2426)
    at android.view.View.updateDisplayListIfDirty(View.java:20830)
    at android.view.View.draw(View.java:21685)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4432)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4193)
    at android.view.View.updateDisplayListIfDirty(View.java:20821)
    at android.view.View.draw(View.java:21685)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4432)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4193)
    at android.view.View.updateDisplayListIfDirty(View.java:20821)
    at android.view.View.draw(View.java:21685)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4432)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4193)
    at android.view.View.updateDisplayListIfDirty(View.java:20821)
    at android.view.View.draw(View.java:21685)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4432)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4193)
    at android.view.View.updateDisplayListIfDirty(View.java:20821)
    at android.view.View.draw(View.java:21685)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4432)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4193)
    at android.view.View.updateDisplayListIfDirty(View.java:20821)
    at android.view.View.draw(View.java:21685)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4432)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4193)
    at android.view.View.updateDisplayListIfDirty(View.java:20821)
    at android.view.View.draw(View.java:21685)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4432)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4193)
    at android.view.View.updateDisplayListIfDirty(View.java:20821)
    at android.view.View.draw(View.java:21685)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4432)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4193)
    at android.view.View.updateDisplayListIfDirty(View.java:20821)
    at android.view.View.draw(View.java:21685)
    at android.view.ViewGroup.drawChild(ViewGroup.java:4432)
    at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4193)
    at android.view.View.draw(View.java:21956)
    at com.android.internal.policy.DecorView.draw(DecorView.java:795)
    at android.view.View.updateDisplayListIfDirty(View.java:20830)
    at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:575)
    at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:581)
    at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:654)
    at android.view.ViewRootImpl.draw(ViewRootImpl.java:3761)
    at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:3489)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2777)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1745)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7730)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:966)
    at android.view.Choreographer.doFrame(Choreographer.java:725)
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:951)
    at android.os.Handler.handleCallback(Handler.java:883)
    at android.os.Handler.dispatchMessage(Handler.java:100)
    at android.os.Looper.loop(Looper.java:214)
    at android.app.ActivityThread.main(ActivityThread.java:7116)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:925)

Answer 1

我很难理解为什么您在不看到代码的某些部分而获得IndexOutOfBoundException。但是，我可以假设，当加载带有WebView的Fragment时，它正在尝试使用一些尚不可用的资源。因此，我想提出解决方法。

您可以考虑设置setOffscreenPageLimit，以便即使您一直滑动也不会重新加载片段。示例代码如下。

ViewPager mViewpager = (ViewPager)findViewById(R.id.viewpager)
mViewPager.setOffscreenPageLimit(3);

我希望能解决您的问题。