Question

我使用searchView获取查询以使用字符串搜索数据库，Cursor不会返回null但是为空。

从我的搜索活动（实现SearchView.OnQueryTextListener的ListActivity）调用搜索：

@Override
    public boolean onQueryTextChange(String newText) {
        // TODO Auto-generated method stub
        //handleIntent(intent);
        Log.d("LIST ACTIVITY SEARCH", "onQueryTextCahanged called: "+ newText);
        Cursor c = data.getWordMatches(newText, null);

        Log.d("LISTACTIVITY", "CURSOR QUERY ROWS/COLS = "+ c.getCount()+" "+c.getColumnCount());

        //now set bind cursor data to list view using custim ItemAdpter class
        adapter = new ItemAdapter(ViewListOfTests.this, c);
        this.setListAdapter(adapter);
        return false;
    }

SQLite Database中的搜索方法从上面的方法获取String查询：

/*
     * methods to search database with String query form searchable widget intent 
    *  in ViewListOfDives ListActivity search bar. Each search returns a cursor which is set to adpter
    *  in ViewListOfYesys List Activity
    */

    public Cursor getWordMatches(String query, String[] columns){

        String selection = database.KEY_TESTNAME + " MATCH ?";
        String[] selectionArgs = new String[] {query+"*"}; //wildcard *

        return query(selection, selectionArgs, columns);


    }//end getWordMatches



    private Cursor query(String selection, String[] selectionArgs,
            String[] columns) {

        // return cursor form params passed getWordMatches(Styring query) from search widget ListActivity

        SQLiteQueryBuilder builder = new SQLiteQueryBuilder();
        builder.setTables(DATABASE_TABLE);

        dbHelperObject = new DbHelper(ourContext);

        Cursor cursor = builder.query(dbHelperObject.getReadableDatabase(), columns, selection, selectionArgs, null, null, null);

        if(cursor == null){
            return null;
        }else if(!cursor.moveToFirst()){
            cursor.close();
            return null;
        }

        return cursor;




    }//end query

如果代码在这里执行，则返回一个空游标：

else if(!cursor.moveToFirst()){
                cursor.close();
                return null;

任何输入赞赏！夏兰

Answer 1

而不是：

if(cursor == null){
    return null;
}else if(!cursor.moveToFirst()){
cursor.close();
   return null;
}

return cursor;

用此：

if(cursor == null){
    return null;
}else{
     cursor.moveToFirst();
}

return cursor;

Answer 2

知道了，好像我把错误的参数传递给了curosr.rawQuery（）。我正在将ref传递给dataBase帮助对象getReadableDB调用：

Cursor cursor = builder.query(mDatabaseOpenHelper.getReadableDatabase(),
            columns, selection, selectionArgs, null, null, null);

当我用数据库对象替换此参数时，它工作正常：

SQLiteDatabase ourDataBase = ourDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

Cursor cursor = builder.query(ourDataBase, columns, selection, selectionArgs, null, null, null);

所述的培训文档通过了前mDatabaseOpenHelper.getReadableDatabase（），但这似乎不起作用，而不是原因。http://developer.android.com/training/search/search.html

搜索SQLite数据库返回空光标

2 个答案: