ListView添加头部之后出现位置获取错乱的问题解决方案

/**

 * Add a fixed view to appear at the top of the list. If addHeaderView is

 * called more than once, the views will appear in the order they were

 * added. Views added using this call can take focus if they want.

 * <p>

 * NOTE: Call this before calling setAdapter. This is so ListView can wrap

 * the supplied cursor with one that that will also account for header

 * views.

 *

 * @param v The view to add.

 * @param data Data to associate with this view

 * @param isSelectable whether the item is selectable

 */

public void addHeaderView(View v, Object data,boolean isSelectable) {

    if (mAdapter != null) {

        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);

}

 

/**

 * Sets the data behind this ListView.

 *

 * The adapter passed to this method may be wrapped by a {@link WrapperListAdapter},

 * depending on the ListView features currently in use. For instance, adding

 * headers and/or footers will cause the adapter to be wrapped.

 *

 * @param adapter The ListAdapter which is responsible for maintaining the

 *        data backing this list and for producing a view to represent an

 *        item in that data set.

 *

 * @see #getAdapter()

 */

@Override

public void setAdapter(ListAdapter adapter) {

    if (null != mAdapter) {

        mAdapter.unregisterDataSetObserver(mDataSetObserver);

    }

 

    resetList();

    mRecycler.clear();

 

    if (mHeaderViewInfos.size() > 0|| mFooterViewInfos.size() > 0) {

        mAdapter = new HeaderViewListAdapter(mHeaderViewInfos, mFooterViewInfos, adapter);

    } else {

        mAdapter = adapter;

    }

 

    //其它的一些代码这里省略之...

}

 

 

从代码和注释里都可以很清楚的得知，addHeaderView一定要在setAdapter之前调用，如果不这样做，addHeaderView会抛出一个异常。Android为什么要这样？这是因为，在setAdapter的时候，会针对我遇到的这种情况（也就是添加Header后position不正确的这种情况）做些特殊的处理。setAdapter在内部判断了当前ListView是否有Header或者Footer，如果没有，就直接使用参数传进来的adapter；如果有，则用一个decorated的HeaderViewListAdapter来替换参数。这个HeaderViewListAdapter的使命，就是排除Header和Footer，让position（当然也包括getItem, getItemId）等方法的position参数）正确返回。

分析到这里，解决方案就出来了：在onItemClick不要直接使用我们声明的adapter，而是用ListView里的那个decorated adapter。获取它的方法就是调用parent.getAdapter()。当然，如果ListView没有Header和Footer，直接使用声明的adapter也没有问题，不过为了避免出错，还是统一使用decorated adapter比较好。

把onItemClick改成下面这样，就可以了

@Override

public void onItemClick(AdapterView<?> parent, View v,int position, long id) {

    //doSomething(parent.getAdapter().getItem(position));

listOut.get((int) parent.getAdapter().getItemId(position)//这是正确的Id

}