关于Listview的一个没有notifyDataSetChanged导致的错误

log为：

java.lang.IllegalStateException: The content of the adapter has changed but ListView did not receive a notification. Make sure the content of your adapter is not modified from a background thread, but only from the UI thread. Make sure your adapter calls notifyDataSetChanged() when its content changes. [in ListView(16908298, class com.handmark.pulltorefresh.library.PullToRefreshListView$InternalListViewSDK9) with Adapter(class android.widget.HeaderViewListAdapter)]错误总结

notifyDataSetChanged    public void notifyDataSetChanged() {            mDataSetObservable.notifyChanged();        }

这个方法内部调用了mDataSetObservable

    public void notifyChanged() {        synchronized(mObservers) {            // since onChanged() is implemented by the app, it could do anything, including            // removing itself from {@link mObservers} - and that could cause problems if            // an iterator is used on the ArrayList {@link mObservers}.            // to avoid such problems, just march thru the list in the reverse order.            for (int i = mObservers.size() - 1; i >= 0; i--) {                mObservers.get(i).onChanged();            }        }    }

可以观察到，notifyChanged最终还是调用了mObservers.get(i).onChanged()这是抽象类DataSetObserver中的一个方法。这个方法通知了listview的数据源发生了改变。

这个方法我们知道对于listview的操作中，如果改变了其adapter的数据内容，是需要去notifyDataSetChanged的，有时你的显示操作改变了adapter，对于一般开发者而言是不会忘记notifyDataSetChanged，并且我们注意到为listview重新设置adapter时也会间接调用onchangd()。

那么为何会导致文章开头的错误呢？原来是因为在fargement中使用了listview导致fragement切换时，被destroy，而导致listview被detachwindow，导致了错误的发生。

  // AbsListView@Override    protected void onDetachedFromWindow() {        super.onDetachedFromWindow();        mIsDetaching = true;        // Dismiss the popup in case onSaveInstanceState() was not invoked        dismissPopup();        // Detach any view left in the scrap heap        mRecycler.clear();        final ViewTreeObserver treeObserver = getViewTreeObserver();        treeObserver.removeOnTouchModeChangeListener(this);        if (mTextFilterEnabled && mPopup != null) {            treeObserver.removeOnGlobalLayoutListener(this);            mGlobalLayoutListenerAddedFilter = false;        }        if (mAdapter != null && mDataSetObserver != null) {            mAdapter.unregisterDataSetObserver(mDataSetObserver);            mDataSetObserver = null;        }

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