addHeaderView()异常 —— setAdapter has already been called

本博文为转载，由于找不到第一作者所以只能留下我转自的地址：
http://blog.csdn.net/shaoyezhangliwei/article/details/50385912

异常提示：java.lang.IllegalStateException: Cannot add header view to list – setAdapter has already been called.
产生原因：addHeaderView()调用在setAdapter()之后，并且该代码运行在Android4.3之前的系统版本。Android SDK与API Level对应表

我们来看看（Android4.3）API-18 和 （Android4.2）API-17的Listview代码片段：

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();  
        }  
}  

在API-17中，假如adapter不为空，则会直接抛出异常，而在API-18中则做了相关的优化。

建议

木有建设性的提议，只能提醒大家，目前市面上主流的Android系统还是Android4.3以下版本，所以在使用addHeaderView()要注意这一点。