Addheaderview () exception -- setadapter has already been called

Exception prompt: Java. Lang. illegalstateexception: cannot add header view to list -- setadapter has already been called.

Cause: addheaderview () is called after setadapter (), and the code runs in the system version before android4.3. Table of Android SDK and API level

 

Let's take a look at the listview code snippets of the (android4.3) API-18 and (android4.2) API-17:

API-18

public void addHeaderView(View v, Object data, boolean isSelectable) {        final FixedViewInfo info = new FixedViewInfo();        info.view = v;        info.data = data;        info.isSelectable = isSelectable;        mHeaderViewInfos.add(info);         // Wrap the adapter if it wasn't already wrapped.        if (mAdapter != null) {            if (!(mAdapter instanceof HeaderViewListAdapter)) {                mAdapter = new HeaderViewListAdapter(mHeaderViewInfos, mFooterViewInfos, mAdapter);            }             // In the case of re-adding a header view, or adding one later on,            // we need to notify the observer.            if (mDataSetObserver != null) {                mDataSetObserver.onChanged();            }        }}

API-17

public void addHeaderView(View v, Object data, boolean isSelectable) {         if (mAdapter != null && ! (mAdapter instanceof HeaderViewListAdapter)) {            throw new IllegalStateException(                    "Cannot add header view to list -- setAdapter has already been called.");        }         FixedViewInfo info = new FixedViewInfo();        info.view = v;        info.data = data;        info.isSelectable = isSelectable;        mHeaderViewInfos.add(info);         // in the case of re-adding a header view, or adding one later on,        // we need to notify the observer        if (mAdapter != null && mDataSetObserver != null) {            mDataSetObserver.onChanged();        }}

In the API-17, if the adapter is not empty, it will directly throw an exception, and in the API-18 is related to the optimization.

Suggestions

We have a constructive proposal and can only remind you that the mainstream Android system on the market is still versions earlier than android4.3. Therefore, pay attention to this when using addheaderview.