恢复带有 webview 的片段时，ViewPager 崩溃

Question

这是我的视图层次结构：

• 协调器布局
  • AppBarLayout
  • 查看页面
    • 4 个片段

第一个片段有一个WebView（根是WebView）。

当在页面之间快速移动时，我最终会收到此错误（随机发生，或在我无法弄清楚的某个位置）从具有WebView 的片段滑开或朝向它。

如果我在不包含 WebViews 的片段之间滑动，无论我滑动多快或滑动多少次，它都可以正常工作。

堆栈跟踪：

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没有看到您的某些部分代码的情况下得到IndexOutOfBoundException。但是，我可以假设，当 Fragment 和 WebView 被加载时，它正在尝试使用一些尚不可用的资源。因此，我想提出一个解决方法。

您可以考虑设置setOffscreenPageLimit，这样即使您一直向下滑动它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);

希望能解决你的问题。