ListView的addHeaderView和setAdapter的调用顺序

标签：listview   setadapter   addheaderview   

ListView想要添加headerview的话，就要通过addHeaderView这个方法，然后想要为ListView设置数据的话，就要调用setAdapter方法了。但是，在调用addHeaderView和setAdapter的顺序上，有时会爆出java.lang.IllegalStateException: Cannot add header view to list -- setAdapter has already been called.的异常。这是因为我们在addHeaderView之前调用了setAdapter。所以，在这里，建议setAdapter需要在addHeaderView和addfooterView之后调用。这样就安全了。下面，我们来看看源码吧。看看究竟是什么原因造成的。

Android-18（4.3）的addHeaderView源码：

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();
            }
        }
}

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();
        }
}

ListView的addHeaderView和setAdapter的调用顺序

标签：listview   setadapter   addheaderview   

原文地址：http://blog.csdn.net/wuzhipeng1991/article/details/39023883