Android 游标列

Question

可以安全地假设 Android 游标仅包含我请求的列，并以与它们在 select 语句中相同的顺序返回它们，即。 e.下面的代码会一直有效吗？

Cursor cursor = db.query("NAMES",
    new String[] {"FIRSTNAME", "LASTNAME", "MOBILE"},
    "ID = " + requestedId, null, null, null, null, null);

if (cursor.moveToFirst()) {
    firstname = cursor.getString(0);
    lastname = cursor.getString(1);
    mobile = cursor.getString(2);
}

或者我应该坚持像下面那样显式获取列索引，因为 Android SQLite 可能会在 query() 返回的游标中添加一些辅助数据或更改列的顺序？

firstname = cursor.getString(cursor.getColumnIndex("FIRSTNAME"));
lastname = cursor.getString(cursor.getColumnIndex("LASTNAME"));
mobile = cursor.getString(cursor.getColumnIndex("MOBILE"));

Answer 1

Is is safe to assume that Android cursor only has the columns I requested and returns them in the same order as they are in the select statement, i. e. will the following code always work?

是的，它很安全。

在幕后，它只是 SQLiteQueryBuilder 进行愚蠢的字符串连接。您可以检查 source了解更多。