Question

简而言之，我的listview使用标准的SimpleQueryAdapter进行过滤，但是当我尝试应用我的自定义SimplyQueryAdapter实现时，它会因异常而中断，我无法弄清楚原因。

在缩减级别，我有一个列出项目的应用程序。我一直在尝试通过用户在相关的EditView中输入的内容“动态”过滤这些结果。

出于测试目的，我的代码只是在列表顶部有一个按钮，当我单击按钮时，它会分配一个FilterQueryProvider并提供一个硬编码的约束字符串。这模拟了一个人在文本字段中键入类似“ob”的内容。

问题是当我尝试运行通过我的自定义SimpleQueryAdapter填充的列表时。每次单击该按钮都会缩小列表但显示不正确的项目，并且还会引发“ java.lang.IllegalStateException ”。例如，我可能会搜索“ob” - 而不是显示“robert”它显示“andrew”。现在更令人担忧的是例外。

以下是完整的例外情况：

04-15 12:23:25.099: ERROR/2130968577MySimpleCursorAdapter.getView(577): java.lang.IllegalStateException: attempt to re-open an already-closed object: android.database.sqlite.SQLiteQuery (mSql = SELECT _id, idSite, idSiteUser, idUser, siteName, siteType, siteUrlIcon, dateModified, siteStatus FROM site WHERE idUser=14742 ORDER BY siteName DESC)

我怀疑Queryadapter出现问题的原因是如果我尝试切换到使用非自定义的SimpleQueryAdapter，它可以很好地工作。但我确实需要实现自定义适配器，因为我正在使用懒惰图标加载等。

我正在以这种方式进行过滤，因为我希望它使用WHERE LIKE（'％blah％'）搜索表，即包含，而不是过滤器。我通过这个帖子找到了这个想法： FilterQueryProvider, filter and ListView

基于异常，似乎我的光标正在关闭，但我不会在任何地方调用，并且适配器应该通过StartManagingCursor自动管理。我是否在数据库连接和游标方面做错了什么？我对FilterQueryProvider的使用是否正确？

这是代码。它的重组是为了简洁

这是我的主要ListActivity：

        public class ChannelListContainer extends ListActivity {
    Context context;
    private MyDBAdapter db;
    private int dummyUserId = 14742;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        context = this.getApplicationContext();

        setContentView(R.layout.channellist);    

        /* open database connection */
        db = new MyDBAdapter(context); 
        db.open();        

        Cursor c = db.fetchAllSites(dummyUserId);
        startManagingCursor(c);

        String[] from = new String[] {DBAdapter.KEY_SITE_NAME}; 
        int[] to = new int[] {R.id.channel_name};

        /// Code using my custom SimpleCursorAdapter (does not work). By swapping between my addapter and the standard cursor adapter i can make it work/not work
        MySimpleCursorAdapter channels = new MySimpleCursorAdapter(this, R.layout.list_item, c, from, to);
        setListAdapter(channels);

    /// Code not using my custom SimpleCursorAdapter (works)
        //SimpleCursorAdapter channels = new SimpleCursorAdapter(this, R.layout.list_item, c, from, to);
        //setListAdapter(channels);
    }       

    private void filterList(CharSequence _constraint) { 
        /// Code using my custom SimpleCursorAdapter (does not work)
        //final MySimpleCursorAdapter channels = (MySimpleCursorAdapter) getListAdapter();

        /// Code not using my custom SimpleCursorAdapter (works)
        final SimpleCursorAdapter channels = (SimpleCursorAdapter) getListAdapter();


        final Cursor oldCursor = channels.getCursor();
        Filter filter;

        channels.setFilterQueryProvider(filterQueryProvider);
        filter = channels.getFilter();
        filter.filter(_constraint, new FilterListener() {
            public void onFilterComplete(int count) {
                stopManagingCursor(oldCursor);
                final Cursor newCursor = channels.getCursor();
                startManagingCursor(newCursor);

                if (oldCursor != null && !oldCursor.isClosed()) {
                    oldCursor.close();
                }
            }

        });
    }

    private FilterQueryProvider filterQueryProvider = new FilterQueryProvider() {
        public Cursor runQuery(CharSequence _constraint) {

            db = new MyDBAdapter(context);
            db.open();
            Cursor c = db.fetchAllSitesByName(dummyUserId, (String) _constraint);

            return c;   
        }
    };

    // filter the list when button called. Demo to filter list to "To Do" item.
    public void onClick(View _view) {
        filterList("To Do");
    }   
}

这是我的Custom SimpleCursorAdapter：

public class MySimpleCursorAdapter extends SimpleCursorAdapter{
    String[] from;
    Cursor c; 
    private static LayoutInflater inflater=null;

    int INDEX_ROWID = 0; 
    int INDEX_IDSITE = 1;
    int INDEX_IDSITEUSER = 2;
    int INDEX_IDUSER = 3;
    int INDEX_SITE_NAME = 4;
    int INDEX_SITE_TYPE = 5;
    int INDEX_SITE_URL_ICON = 6;
    int INDEX_DATE_MODIFIED = 7;

    public MySimpleCursorAdapter(Activity activity, int layout, Cursor cursor, String[] from, int[] to) {

        super(activity.getApplicationContext(), layout, cursor, from, to);
        this.from = from;
        this.c = cursor;
        inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    public static class ViewHolder{
        public TextView channel_name;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        View vi=convertView;   

        try {
            ViewHolder holder;
            if (this.c.moveToPosition(position)) {
                if(convertView==null){
                    vi = inflater.inflate(R.layout.list_item, null);
                    holder=new ViewHolder(); 
                    holder.channel_name=(TextView)vi.findViewById(R.id.channel_name);
                    vi.setTag(holder); 
                }
                else {
                    holder=(ViewHolder)vi.getTag();
                }                 

                holder.channel_name.setText(c.getString(INDEX_SITE_NAME));

                return vi;  
            }

        } catch (Exception e) {
            Log.e(R.string.app_name + "MySimpleCursorAdapter.getView",e.toString());
        }
        return vi;  
    }
}

数据库打开：

public MyDBAdapter(Context _context) {
    context = _context;
    dbHelper = new myDbHelper(context, DATABASE_NAME, null, DATABASE_VERSION);
}

public MyDBAdapter open() throws SQLException {
    db = dbHelper.getWritableDatabase();
    return this;
}

非常感谢任何帮助。

谢谢，罗布

ListView，Custom SimpleCursorAdapter＆amp; FilterQueryProvider

0 个答案: