我尽力了,但是我无法获取到光标返回的任何数据。我已经确认数据库中有数据并且插入操作正常。官方错误提示如下:
CursorIndexOutOfBoundsException: 索引为0,大小为0
顶级声明:
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx)
{
this.context = ctx;
DBHelper = new DatabaseHelper(context);
this.db = this.DBHelper.getWritableDatabase();
}
我的功能:
public String getRandomEntry()
{
int rand;
Random random = new Random();
int numEntries = (int)this.getCount();
if(numEntries == 0)
return "ERROR: Database is empty.";
rand = random.nextInt(numEntries);
Cursor cursor = DBHelper.getWritableDatabase().rawQuery(
"SELECT * FROM " + DATABASE_TABLE
+ " WHERE " + COLUMN_A + " = " + 0, null);
Log.i("numEntries", Integer.toString(numEntries));
Log.i("rand", Integer.toString(rand));
Log.i("cursor", Integer.toString(cursor.getCount()));
cursor.moveToFirst();
return cursor.getString(0);
}
我也尝试过这样抓取光标:
Cursor cursor = db.rawQuery(
"SELECT * FROM " + DATABASE_TABLE
+ " WHERE " + COLUMN_A + " = " + 0, null);
请给我您的想法!谢谢!!
(这段话无需翻译)