Cannot call this method while RecyclerView is computing a layout or scrolling android.support.v7.wid

Cannot call this method while RecyclerView is computing a layout or scrolling android.support.v7.widget.RecyclerView



今天在使用RecyclerView.notifyDataSetChanged的时候报了这个异常，是数据刷新时间间矩很快的情况下出现的，字面意思是不能在RecyclerView计算布局或者滚动的时候使用这个方法，那么其他的notifyXXX之类的方法也是类似的。

最后翻了下RecyclerView的源码看到了这个方法

/**
* Returns whether RecyclerView is currently computing a layout.
* <p>
* If this method returns true, it means that RecyclerView is in a lockdown state and any
* attempt to update adapter contents will result in an exception because adapter contents
* cannot be changed while RecyclerView is trying to compute the layout.
* <p>
* It is very unlikely that your code will be running during this state as it is
* called by the framework when a layout traversal happens or RecyclerView starts to scroll
* in response to system events (touch, accessibility etc).
* <p>
* This case may happen if you have some custom logic to change adapter contents in
* response to a View callback (e.g. focus change callback) which might be triggered during a
* layout calculation. In these cases, you should just postpone the change using a Handler or a
* similar mechanism.
*
* @return <code>true</code> if RecyclerView is currently computing a layout, <code>false</code>
*         otherwise
*/
public boolean isComputingLayout() {
return mLayoutOrScrollCounter > 0;
}

这个方法注释的意思大致是这样的：

如果此方法返回true，则意味着循环视图处于锁定状态，并尝试更新适配器内容，将导致异常，因为适配器无法更改，而循环视图则试图计算布局。在此状态下，您的代码不太可能会运行，因为当一个布局遍历发生或重新使用时，框架会调用它来响应系统事件(触摸、可访问性等)。如果您有一些自定义逻辑来响应视图回调(例如焦点更改回调)，在布局计算过程中可能会触发该事件，则可能会发生这种情况。在这些情况下，您应该使用处理程序或类似的机制来延迟更改。

那么最后处理的方法是先判断这个 是否为true,再进行notifyXXX的操作。中间我是使用的递归实现，大家用handler之类的也是可以的。我的解决方法如下，Kotlin代码：

/**
* 预搜索返回数据
* 这里要先解决这个问题
* java.lang.IllegalStateException: Cannot call this method while RecyclerView is computing a layout or scrolling android.support.v7.widget.RecyclerView
*/
override fun bindPreSearchData(data: List<KeywordBean>) {
// 这里返回数据后要把数据绑定给对应的view
if (preSearchRc.isComputingLayout) {
// 延时递归处理。
preSearchRc.postDelayed({
bindPreSearchData(data)
}, 100)
} else {
preDatas?.clear()
preDatas?.addAll(data)
preSearchingAdapter?.setKeyword(etSearch.text.toString().trim())
preSearchingAdapter?.notifyDataSetChanged()
preSearchRc.visibility = View.VISIBLE
}
}

记录这个问题希望对自己和大家能有所帮助。