addHeaderView()异常 —— setAdapter has already been called

标签：listview   addheaderview   

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。

addHeaderView()异常 —— setAdapter has already been called,布布扣,bubuko.com

addHeaderView()异常 —— setAdapter has already been called

标签：listview   addheaderview   

原文地址：http://blog.csdn.net/mtt1987/article/details/38535249