两三个页面的情况下，快速连续滑动返回会崩溃

[androiddream]

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setX(float)' on a null object reference
at com.aitangba.swipeback.SwipeBackHelper$ViewManager.translateViews(SwipeBackHelper.java:388)
at com.aitangba.swipeback.SwipeBackHelper$ViewManager.access$300(SwipeBackHelper.java:268)
at com.aitangba.swipeback.SwipeBackHelper.setTranslationX(SwipeBackHelper.java:209)
at com.aitangba.swipeback.SwipeBackHelper.processTouchEvent(SwipeBackHelper.java:111)
at cn.kunming.common.activity.SwipeBackActivity.dispatchTouchEvent(SwipeBackActivity.java:33)
at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:69)
at android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:69)
at com.android.internal.policy.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2405)
at android.view.View.dispatchPointerEvent(View.java:9548)
at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4515)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4313)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3823)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3883)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3842)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3990)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3850)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4047)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3823)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3883)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3842)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3850)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3823)
at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:6239)
at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:6213)
at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6174)
at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:6346)
at android.view.ViewRootImpl$ColorWindowInputEventReceiver.onInputEvent(ViewRootImpl.java:7598)
at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
at android.view.InputEventReceiver.nativeConsumeBatchedInputEvents(Native Method)
at android.view.InputEventReceiver.consumeBatchedInputEvents(InputEventReceiver.java:176)
at android.view.ViewRootImpl.doConsumeBatchedInput(ViewRootImpl.java:6313)
at android.view.ViewRootImpl$ConsumeBatchedInputRunnable.run(ViewRootImpl.java:6369)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:862)
at android.view.Choreographer.doCallbacks(Choreographer.java:674)
at android.view.Choreographer.doFrame(Choreographer.java:604)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:848)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:179)
at android.app.ActivityThread.main(ActivityThread.java:5769)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:674)