android - 光标找不到列？

Question

我试图从表中加载值列表，但游标找不到列？ 有问题的代码:

public final AccessToken[] fetchAccessTokenByServerId(final long serverId) {
    final Cursor c = db.query(
            ACCESS_TOKEN_TABLE,
            new String[] { ACCESS_TOKEN_COL_ID, ACCESS_TOKEN_COL_VALUE },
            ACCESS_TOKEN_COL_SERVER_ID + "=?",
            new String[] { Long.toString(serverId) },
            null,
            null,
            null);

    AccessToken[] result = new AccessToken[c.getCount()];
    for (int i = 0; i < result.length; i++) {
        long id = c.getLong(c.getColumnIndexOrThrow(ACCESS_TOKEN_COL_ID));
        String value = c.getString(c.getColumnIndexOrThrow(ACCESS_TOKEN_COL_VALUE));

        result[i] = new AccessToken(value, id, serverId);
        c.moveToNext();
    }
    return result;
}

public static final String COL_ID = "_id";
public static final String ACCESS_TOKEN_TABLE = "accesstoken";
public static final String ACCESS_TOKEN_COL_ID = COL_ID;
public static final String ACCESS_TOKEN_COL_SERVER_ID = "server_id";
public static final String ACCESS_TOKEN_COL_VALUE = "value";

但是 for 循环中的前两个语句失败了:

Index -1 is requested, with a size of 1

该表包含以下列:_id (= int)、server_id (= int) 和 value (= string)

只有一个条目:1, 1, test

函数的参数为​​1。

真诚的 徐子泽

Answer 1

在初始化你的游标之后，执行以下操作:

c.moveToFirst();