今天做了一个下拉页面（类似于淘宝“下拉继续查看详情”）、下方的页面是多个Fragment组成，也就用到了ViewPager，双指下拉的时候就偶现异常，如下：
Android java.lang.IllegalArgumentException: pointerIndex out of range pointerIndex=-1 pointerCount=1
java.lang.IllegalArgumentException: pointerIndex out of range pointerIndex=-1 pointerCount=1
at android.view.MotionEvent.nativeGetAxisValue(Native Method)
at android.view.MotionEvent.getX(MotionEvent.java:2203)
at android.support.v4.view.MotionEventCompatEclair.getX(MotionEventCompatEclair.java:32)
at android.support.v4.view.MotionEventCompat$EclairMotionEventVersionImpl.getX(MotionEventCompat.java:110)
at android.support.v4.view.MotionEventCompat.getX(MotionEventCompat.java:462)
at android.support.v4.view.ViewPager.onInterceptTouchEvent(ViewPager.java:1987)
at tf.view.DetailViewPager.onInterceptTouchEvent(DetailViewPager.java:36)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2515)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2974)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2661)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2974)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2661)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2974)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2661)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2974)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2661)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2974)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2661)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2974)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2661)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2974)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2661)
at com.android.internal.policy.DecorView.superDispatchTouchEvent(DecorView.java:548)
at com.android.internal.policy.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1953)
at android.app.Activity.dispatchTouchEvent(Activity.java:3545)
at com.android.internal.policy.DecorView.dispatchTouchEvent(DecorView.java:501)
at android.view.View.dispatchPointerEvent(View.java:12027)
at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:5219)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:5009)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4523)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4576)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4542)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4669)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4550)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4726)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4523)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4576)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4542)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4550)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4523)
at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:7098)
at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:7072)
at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:7033)
at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:7252)
at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:192)
at android.view.InputEventReceiver.nativeConsumeBatchedInputEvents(Native Method)
at android.view.InputEventReceiver.consumeBatchedInputEvents(InputEventReceiver.java:181)
at android.view.ViewRootImpl.doConsumeBatchedInput(ViewRootImpl.java:7177)
at android.view.ViewRootImpl$ConsumeBatchedInputRunnable.run(ViewRootImpl.java:7280)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:974)
at android.view.Choreographer.doCallbacks(Choreographer.java:783)
at android.view.Choreographer.doFrame(Choreographer.java:708)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:960)
at android.os.Handler.handleCallback(Handler.java:808)
at android.os.Handler.dispatchMessage(Handler.java:101)
at android.os.Looper.loop(Looper.java:166)
at android.app.ActivityThread.main(ActivityThread.java:7390)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:245)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:926)
异常分析：类似此种系统性异常，尽可能得去捕获了
比如：viewpager,我们直接重写这两个方法，然后捕获异常
