那些遇到过的问题

ViewDragHelper.getTouchSlop（）上的NullPointerException

Cos*_*scu 5 java android nullpointerexception

我有一个问题，一个奇怪的问题，我无法复制，但是我看到很多用户都存在该问题。坠机事故由Crashlitycs捕获。问题是：

致命异常：java.lang.NullPointerException尝试在空对象引用上调用虚拟方法'int android.support.v4.widget.ViewDragHelper.getTouchSlop（）'

目前，我已将支持库设置为28.0.0。

我不知道下一步该怎么做，因为我不知道此错误来自何处，并且无法复制它

final SUPPORT_LIBRARY_VERSION = '28.0.0'

// Support
implementation "com.android.support:design:$SUPPORT_LIBRARY_VERSION"
implementation "com.android.support:appcompat-v7:$SUPPORT_LIBRARY_VERSION"
implementation "com.android.support:cardview-v7:$SUPPORT_LIBRARY_VERSION"
implementation "com.android.support:recyclerview-v7:$SUPPORT_LIBRARY_VERSION"
implementation 'com.android.support.constraint:constraint-layout:1.1.1'
implementation "com.android.support:exifinterface:$SUPPORT_LIBRARY_VERSION"
implementation "com.android.support:support-media-compat:$SUPPORT_LIBRARY_VERSION"
implementation "com.android.support:support-v4:$SUPPORT_LIBRARY_VERSION"
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这是我的Logcat

       at android.support.design.widget.BottomSheetBehavior.onTouchEvent(BottomSheetBehavior.java:350)
       at android.support.design.widget.CoordinatorLayout.performIntercept(CoordinatorLayout.java:476)
       at android.support.design.widget.CoordinatorLayout.onTouchEvent(CoordinatorLayout.java:527)
       at android.view.View.dispatchTouchEvent(View.java:9390)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2549)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2240)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at com.android.internal.policy.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2461)
       at com.android.internal.policy.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1777)
       at android.app.Activity.dispatchTouchEvent(Activity.java:2865)
       at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:69)
       at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:69)
       at com.android.internal.policy.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2422)
       at android.view.View.dispatchPointerEvent(View.java:9610)
       at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4447)
       at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4313)
       at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3847)
       at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3900)
       at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3866)
       at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3992)
       at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3874)
       at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4049)
       at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3847)
       at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3900)
       at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3866)
       at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3874)
       at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3847)
       at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:6146)
       at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:6120)
       at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6081)
       at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:6262)
       at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:192)
       at android.os.MessageQueue.nativePollOnce(MessageQueue.java)
       at android.os.MessageQueue.next(MessageQueue.java:330)
       at android.os.Looper.loop(Looper.java:137)
       at android.app.ActivityThread.main(ActivityThread.java:5621)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:684)

--

Fatal Exception: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.support.v4.widget.ViewDragHelper.getTouchSlop()' on a null object reference
       at android.support.design.widget.BottomSheetBehavior.onTouchEvent(BottomSheetBehavior.java:350)
       at android.support.design.widget.CoordinatorLayout.performIntercept(CoordinatorLayout.java:476)
       at android.support.design.widget.CoordinatorLayout.onTouchEvent(CoordinatorLayout.java:527)
       at android.view.View.dispatchTouchEvent(View.java:9390)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2549)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2240)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at com.android.internal.policy.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2461)
       at com.android.internal.policy.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1777)
       at android.app.Activity.dispatchTouchEvent(Activity.java:2865)
       at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:69)
       at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:69)
       at com.android.internal.policy.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2422)
       at android.view.View.dispatchPointerEvent(View.java:9610)
       at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4447)
       at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4313)
       at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3847)
       at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3900)
       at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3866)
       at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3992)
       at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3874)
       at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4049)
       at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3847)
       at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3900)
       at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3866)
       at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3874)
       at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3847)
       at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:6146)
       at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:6120)
       at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6081)
       at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:6262)
       at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:192)
       at android.os.MessageQueue.nativePollOnce(MessageQueue.java)
       at android.os.MessageQueue.next(MessageQueue.java:330)
       at android.os.Looper.loop(Looper.java:137)
       at android.app.ActivityThread.main(ActivityThread.java:5621)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:684)

#0. Crashed: main
       at android.support.design.widget.BottomSheetBehavior.onTouchEvent(BottomSheetBehavior.java:350)
       at android.support.design.widget.CoordinatorLayout.performIntercept(CoordinatorLayout.java:476)
       at android.support.design.widget.CoordinatorLayout.onTouchEvent(CoordinatorLayout.java:527)
       at android.view.View.dispatchTouchEvent(View.java:9390)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2549)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2240)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2555)
       at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2254)
       at com.android.internal.policy.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2461)
       at com.android.internal.policy.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1777)
       at android.app.Activity.dispatchTouchEvent(Activity.java:2865)
       at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:69)
       at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:69)
       at com.android.internal.policy.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2422)
       at android.view.View.dispatchPointerEvent(View.java:9610)
       at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4447)
       at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4313)
       at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3847)
       at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3900)
       at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3866)
       at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3992)
       at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3874)
       at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4049)
       at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3847)
       at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3900)
       at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3866)
       at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3874)
       at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3847)
       at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:6146)
       at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:6120)
       at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6081)
       at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:6262)
       at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:192)
       at android.os.MessageQueue.nativePollOnce(MessageQueue.java)
       at android.os.MessageQueue.next(MessageQueue.java:330)
       at android.os.Looper.loop(Looper.java:137)
       at android.app.ActivityThread.main(ActivityThread.java:5621)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:684)
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目前，我扩展BottomSheetDialogFragment了很多片段（嗯，几乎所有片段）

Tat*_*ize 0

回头检查源代码中的行：

return action == MotionEvent.ACTION_MOVE
        && scroll != null
        && !ignoreEvents
        && state != STATE_DRAGGING
        && !parent.isPointInChildBounds(scroll, (int) event.getX(), (int) event.getY())
        && Math.abs(initialY - event.getY()) > viewDragHelper.getTouchSlop();
  }
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似乎在更高版本中读到：

 return action == MotionEvent.ACTION_MOVE
        && scroll != null
        && !ignoreEvents
        && state != STATE_DRAGGING
        && !parent.isPointInChildBounds(scroll, (int) event.getX(), (int) event.getY())
        && viewDragHelper != null
        && Math.abs(initialY - event.getY()) > viewDragHelper.getTouchSlop();
  }
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看来应该修复一下了。尽管其他一些函数似乎清除了 viewDragHelper 值，因此通常很难重现。

在某些版本中，如果在调用 onLayoutChild() 之前执行触摸移动，您可能会收到空指针错误。看来这可能很难做到。但是，没有明确检查它。

显然它应该被修复，但我没有看到源代码中的明确检查，并且它们的复制步骤无论如何都可能对您有所帮助。

https://github.com/material-components/material-components-android/issues/43

“在构建布局时，通过向底部表单发送大量触摸事件，可能会在较旧/较慢的设备上发生这种情况。”

归档时间：

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6 年，5 月 前
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