这是我的问题:

Cursor nextdate(String Date) {
    SQLiteDatabase db = this.getReadableDatabase();
    String[] params = new String[]{String.valueOf(Date)};
    Cursor cur = db.rawQuery(" SELECT MIN (" + colDateDue + ") FROM " + PAYMENTS + " WHERE " + colDateDue + ">=?", params);
    cur.moveToFirst();
    return cur;
}

我想在textview中显示查询的结果,但是我不知道如何显示,所以我自然会寻找答案。我找到了几个答案,然后得出了这个结论:
DatabaseHelper db = new DatabaseHelper(this);
String str = "";
    if (c!= null) {
        if (c.moveToFirst()) {
            str = c.getString(c.getColumnIndex(db.colDateDue);
        }
    }
TextView.setText(str);

但我明白了
Caused by: java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow.  Make sure the Cursor is initialized correctly before accessing data from it.

这让我有点困惑,因为通常的错误修复方法是使用cur.moveToFirst();这两种情况下都使用…我到底做错了什么?

最佳答案

这样试试:
将列索引保留为0,因为该游标将只有一列。

DatabaseHelper db = new DatabaseHelper(this);
String str = "";
    if (c!= null) {
        if (c.moveToFirst()) {
            str = c.getString(0);
        }
    }
TextView.setText(str);

10-07 19:23
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