我首先要说的是我已经研究过这个特定的死亡解决方案，并且我知道解决方案"this has been solved HERE"和HERE，但我无法让这些解决方案工作。其他信息：我正在使用兼容性库以及actionbarsherlock，它们都运行良好，没有任何问题，我不这么认为。
我有一个SQLite数据库，我希望将我的条目填入按日期分组的可扩展列表中。我知道我的数据库已正确填充，这里是我已经验证包含正确数据的列：
ID (1, 2, 3, 4, etc)
TITLE (some text)
URL (url as string)
DATE (ddMMyyyy)
其中日期列数据如下：22Dec2012或23Dec2012等。
每个日期有很多条目，我想将这些条目分组为日期作为组的子项。我看到数据库中填充了正确的信息。我有一些问题，主要是我的getChildrenCursor永远不会被调用，只有构造函数被调用。其次是根据链接的示例，我无法将getSherlockActivity上下文放入我的适配器中（getActivity（）也不能正常工作，仅用于测试目的）。我将在下面用logcat解释错误。
我的片段
public class MyFragment extends SherlockFragment implements LoaderManager.LoaderCallbacks, OnItemClickListener {
public static MyFragment newInstance(String symbol) {
MyFragment f = new MyFragment();
Bundle args = new Bundle();
args.putString(Consts.INFO, info);
f.setArguments(args);
return f;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View myView = inflater.inflate(R.layout.fragment_layout3, container, false);
mListView = (ExpandableListView)myView.findViewById(R.id.expandableListView);
mListView.setOnItemClickListener(this);
return myView;
}
@Override
public void onPause() {
super.onPause();
}
@Override
public void onResume() {
super.onResume();
refresh();
}
public void refresh() {
Log.v(TAG, "refresh");
populateExpandableList();
loader = getLoaderManager().getLoader(-1);
if (loader != null && !loader.isReset()) {
getLoaderManager().restartLoader(-1, null, this);
} else {
getLoaderManager().initLoader(-1, null, this);
}
if (getLoaderManager().getLoader(0x9999) == null) {
getLoaderManager().initLoader(0x9999, null, this);
//getLoaderManager().initLoader(-1, null, this);
}
else {
getLoaderManager().restartLoader(0x9999, null, this);
//getLoaderManager().restartLoader(-1, null, this);
}
getLoaderManager().getLoader(0x9999).forceLoad();
//getLoaderManager().getLoader(1).forceLoad();
}
private void populateExpandableList() {
// Set up our adapter
Log.v(TAG, "Endtering setup adapter");
mDbHelper = new DBHelper(getSherlockActivity(), DBConstants.DATABASE_NAME, null, DBConstants.DATABASE_VERSION);
mAdapter = new MyExpandableAdapter(getSherlockActivity(), this,
R.layout.news_list_group,
R.layout.news_list_child,
new String[] { DBConstants.DATE_GROUP_NAME }, // Name for group layouts
new int[] { R.id.group_title },
new String[] { DBConstants.TITLE_NAME, DBConstants.URL_NAME }, // Name for child layouts
new int[] { R.id.item_title, R.id.item_value });
mListView.setAdapter(mAdapter);
}
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
// TODO Auto-generated method stub
}
@Override
public Loader onCreateLoader(int loaderId, Bundle args) {
topics = new ArrayList<String>();
if (loaderId == 0x9999) {
return new MyLoader(getSherlockActivity(), mHandler, topics.toArray(new String[topics.size()]));
}
if (loaderId != -1 && loaderId != 0x9999) {
Log.v(TAG, "CreateLoader child cursor: loader ID: "+loaderId);
// child cursor
mCursorLoader = new SQLiteCursorLoader(getSherlockActivity(), mDbHelper, "SELECT _ID, "+DBConstants.TITLE+", " +DBConstants.URL + ", " + DBConstants.TIME + ", " + DBConstants.STATUS + " FROM "+DBConstants.TABLE+" WHERE "+ DBConstants.KEY_ID+"="+String.valueOf(loaderId)+" ORDER BY "+DBConstants.TIME+" DESC", null);
return mCursorLoader;
}
else if (loaderId != 0x9999) {
Log.v(TAG, "CreateLoader group cursor: loader ID: "+loaderId);
// group cursor
mCursorLoader = new SQLiteCursorLoader(getSherlockActivity(), mDbHelper, "SELECT date, "+DBConstants.TITLE+", "+DBConstants.URL+" FROM "+DBConstants.TABLE, null);
return mCursorLoader;
}
return null;
}
@Override
public void onLoadFinished(Loader loader, Object result) {
Log.v(TAG, "onLoadFinished");
if(result != null /*&& result.length > 0*/) {
if (loader.getId() == 0x9999) {
getLoaderManager().restartLoader(-1, null, this);
getLoaderManager().getLoader(-1).forceLoad();
}
if (loader.getId() != -1 && loader.getId() != 0x9999) {
Log.v(TAG, "LoadFinished second loader: loaderID: "+loader.getId());
if (!((Cursor) result).isClosed()) {
Log.v(TAG, "data.getCount() " + ((Cursor) result).getCount());
HashMap<Integer,Integer> groupMap = mAdapter.getGroupMap();
try {
int groupPos = groupMap.get(loader.getId());
Log.v(TAG, "onLoadFinished() for groupPos " + groupPos);
mAdapter.setChildrenCursor(groupPos, (Cursor) result);
} catch (NullPointerException e) {
Log.w("DEBUG","Adapter expired, try again on the next query: "
+ e.getMessage());
}
}
else {
mAdapter.setGroupCursor((Cursor) result);
}
}
else {
}
}
}
@Override
public void onLoaderReset(Loader loader) {
int id = loader.getId();
Log.v(TAG, "onLoaderReset() for loader_id " + id);
if (id != -1) {
// child cursor
try {
mAdapter.setChildrenCursor(id, null);
} catch (NullPointerException e) {
Log.w("TAG", "Adapter expired, try again on the next query: "
+ e.getMessage());
}
} else {
mAdapter.setGroupCursor(null);
}
}
public class MyExpandableAdapter extends SimpleCursorTreeAdapter {
private final String TAG = getClass().getSimpleName().toString();
private MyFragment mFragment;
protected HashMap<Integer, Integer> mGroupMap = null;
public NewsFeedExpandableAdapter(Context context, MyFragment mf, int groupLayout, int childLayout, String[] groupFrom,
int[] groupTo, String[] childrenFrom, int[] childrenTo) {
super(context, null, groupLayout, groupFrom, groupTo, childLayout, childrenFrom, childrenTo);
mFragment = mf;
mGroupMap = new HashMap<Integer, Integer>();
Log.v(TAG, "Adapter constructor");
}
@Override
protected Cursor getChildrenCursor(Cursor groupCursor) {
// Given the group, we return a cursor for all the children within that group
Log.v(TAG, "getChildrenCursor");
int groupPos = groupCursor.getPosition();
int groupId = groupCursor.getInt(groupCursor.getColumnIndex(DBConstants.TIME_GROUP_NAME));
Log.v(TAG, "getChildrenCursor() for groupPos " + groupPos);
Log.v(TAG, "getChildrenCursor() for groupId " + groupId);
mGroupMap.put(groupId, groupPos);
Loader loader = mFragment.getLoaderManager().getLoader(groupId);
if ( loader != null && !loader.isReset() ) {
mFragment.getLoaderManager().restartLoader(groupId, null, mFragment);
} else {
mFragment.getLoaderManager().initLoader(groupId, null, mFragment);
}
return null;
}
//Accessor method
public HashMap<Integer, Integer> getGroupMap() {
return mGroupMap;
}
}
}
现在在上面的适配器中，你看到我正在使用：
Loader loader = mFragment.getLoaderManager().getLoader(groupId);
if ( loader != null && !loader.isReset() ) {
mFragment.getLoaderManager().restartLoader(groupId, null, mFragment);
} else {
mFragment.getLoaderManager().initLoader(groupId, null, mFragment);
}
而不是：
Loader loader = getSherlockActivity().getLoaderManager().getLoader(groupId);
if ( loader != null && !loader.isReset() ) {
getSherlockActivity().getLoaderManager().restartLoader(groupId, null, mFragment);
} else {
getSherlockActivity().getLoaderManager().initLoader(groupId, null, mFragment);
}
因为当我使用getActivity或getSherlockActivity时，代码在上面的第一行给出错误说：
"Type mismatch, cannot convert from Loader<Object> to Loader"
以及第三和第五行错误：
"The method restartLoader(int, Bundle, LoaderManager.LoaderCallbacks<D>) in the type LoaderManager is not applicable for the arguments (int, null, MyFragment)"
有谁可能知道为什么我不能在这里使用getActivity？这让我完全疯狂。所以我尝试使用mFragment.getLoaderManager而不是使用传入适配器的片段，但我不知道这是否正确。
我在代码中放置了断点，它表明调用了适配器构造函数，就是这样，getChildrenCursor永远不会被调用。在片段断点中，它达到“Create Group Loader id = -1”就可以了。在onLoadFinished中，只有第一个“onLoadFinished”标记在日志中显示。它永远不会进入onLoadFinished中的IF语句。当我在logcat中检查loadFinished结果是否为空时，它显示为传入onLoadFinished的游标对象，但是某些东西不能正常工作。
在尝试可扩展列表之前，我正在使用这些相同的SQLiteCursorLoader设置，只检索所有列，并且它们工作正常。我绝对承认，也许我的SELECT语句都不正确。但我已经尝试了大量不同的选择查询，每次我得到相同的结果，什么也没有。任何人都可以帮助我，我绝望和疯狂。感谢。