NestedScrollView引起的ViewGroup 异常： parameter must be a descendant of this view

异常信息

大致的异常信息如下：

java.lang.IllegalArgumentException: parameter must be a descendant of this viewE/DEBUG:     at android.view.ViewGroup.offsetRectBetweenParentAndChild(ViewGroup.java:6376)at android.view.ViewGroup.offsetDescendantRectToMyCoords(ViewGroup.java:6305)at androidx.core.widget.NestedScrollView.isWithinDeltaOfScreen(NestedScrollView.java:1387)at androidx.core.widget.NestedScrollView.onSizeChanged(NestedScrollView.java:1872)at android.view.View.sizeChange(View.java:22338)at android.view.View.setFrame(View.java:22290)at android.view.View.layout(View.java:22144)at android.view.ViewGroup.layout(ViewGroup.java:6493)at androidx.constraintlayout.widget.ConstraintLayout.onLayout(ConstraintLayout.java:1915)

异常发生时机

界面的大概视图布局NestedScrollView中嵌套了几个RecyclerView，还有普通的视图，其中一个RecyclerView 主要做商品类型的展现，需要用户手动点击添加，如下列图：


点击类型后面的EditText输入内容以后，再点击旁边的图标选择相册图片，然后返回构建视图时，界面闪退。

异常定位分析

看异常信息分析，应该是我视图布局中的NestedScrollView 在onSizeChanged的时候调用isWithinDeltaOfScreen方法，在调用ViewGroup的offsetDescendantRectToMyCoords方法，最终在offsetRectBetweenParentAndChild方法中抛出异常：

 protected void onSizeChanged(int w, int h, int oldw, int oldh) {super.onSizeChanged(w, h, oldw, oldh);View currentFocused = findFocus();if (null == currentFocused || this == currentFocused) {return;}// If the currently-focused view was visible on the screen when the// screen was at the old height, then scroll the screen to make that// view visible with the new screen height.if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) {currentFocused.getDrawingRect(mTempRect);offsetDescendantRectToMyCoords(currentFocused, mTempRect);int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);doScrollY(scrollDelta);}}

void offsetRectBetweenParentAndChild(View descendant, Rect rect,boolean offsetFromChildToParent, boolean clipToBounds) {// already in the same coord system :)if (descendant == this) {return;}ViewParent theParent = descendant.mParent;// search and offset up to the parentwhile ((theParent != null)&& (theParent instanceof View)&& (theParent != this)) {if (offsetFromChildToParent) {rect.offset(descendant.mLeft - descendant.mScrollX,descendant.mTop - descendant.mScrollY);if (clipToBounds) {View p = (View) theParent;boolean intersected = rect.intersect(0, 0, p.mRight - p.mLeft,p.mBottom - p.mTop);if (!intersected) {rect.setEmpty();}}} else {if (clipToBounds) {View p = (View) theParent;boolean intersected = rect.intersect(0, 0, p.mRight - p.mLeft,p.mBottom - p.mTop);if (!intersected) {rect.setEmpty();}}rect.offset(descendant.mScrollX - descendant.mLeft,descendant.mScrollY - descendant.mTop);}descendant = (View) theParent;theParent = descendant.mParent;}// now that we are up to this view, need to offset one more time// to get into our coordinate spaceif (theParent == this) {if (offsetFromChildToParent) {rect.offset(descendant.mLeft - descendant.mScrollX,descendant.mTop - descendant.mScrollY);} else {rect.offset(descendant.mScrollX - descendant.mLeft,descendant.mScrollY - descendant.mTop);}} else {throw new IllegalArgumentException("parameter must be a descendant of this view");}}

看视图看异常信息，怎么也想不到 参数为啥不是此视图的子视图，后来追源码，看onSizeChanged里View currentFocused = findFocus() 这行代码，突然想到了当前的输入法软键盘，然后就怀疑是输入法键盘的问题，于是我做了一个测试，输入文字信息以后，手动收回输入法键盘，再去点击旁边的小图标选择相册，果然返回正常的。
那么异常原因应该可以得到定位了，估计是因为输入法软键盘弹起，在NestedScrollView 的onSizeChanged方法回调时，输入法键盘获取到焦点，最终导致这个异常的发生。

异常解决方案

两个方案：
1、界面跳转选择相册时，先隐藏掉输入法，这样返回来构建界面时就不会抛这个异常了，比如下面代码实现：

R.id.goodsTypeImageIv ->{// 跳转之前，将输入法隐藏掉ApplictionUtil.hidenInputMethod(goodsTypeRecyclerView, this)mGoodsTypeCurrentIndex = positionmAddImageHelper.selectImageSingle(this,REQUEST_ADD_GOODS_TYPE_IMAGE)
}

2、还有一个思路，就是在输入法软键盘弹出时，不对界面window的大小进行调整，配置activity的windowSoftInputMode属性为adjustPan即可

android:windowSoftInputMode="stateHidden|adjustPan"

配置adjustPan有可能会造成界面显示不友好，如果必须要用adjustResize，那么还是使用第一个解决方案，点击跳转前，先隐藏掉输入法。