获取最后一个 _id 时出现 CursorIndexOutOfBoundsException？

Question

我正在尝试从数据库插入的最后一行（_id）中提取数据。我不知道我有什么错/遗漏。感谢您的帮助！

ERROR/AndroidRuntime(363): Caused by: android.database.CursorIndexOutOfBoundsException: 
                                      Index -1 requested, with a size of 1

爪哇：

 else { // Otherwise start the application here:

        Cursor c = db.rawQuery(
                "SELECT * FROM History_List ORDER BY _id desc limit 1",
                null);

        int nI = c.getColumnIndexOrThrow("intent");
        String intent = c.getString(nI);
        Class<?> nIntent = null;
        try {
            nIntent = Class.forName("com.aeroTechnologies.flyDroid."
                    + intent);
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        int tvLabel = c.getColumnIndexOrThrow("label");
        String label = c.getString(tvLabel);

        int tvTitle = c.getColumnIndexOrThrow("title");
        String title = c.getString(tvTitle);

        int tvDescript = c.getColumnIndexOrThrow("description");
        String descript = c.getString(tvDescript);

        int tvURL = c.getColumnIndexOrThrow("gotoURL");
        String url = c.getString(tvURL);

        int yPOS = c.getColumnIndexOrThrow("scrollY");
        String ypos = c.getString(yPOS);

        Intent i = new Intent(Start.this, nIntent);

        i.putExtra("KEY_LABEL", label);
        i.putExtra("KEY_TITLE", title);
        i.putExtra("KEY_DESCRIPT", descript);
        i.putExtra("KEY_URL", url);
        i.putExtra("KEY_INTENT", intent);
        i.putExtra("KEY_YPOS", ypos);
        startActivity(i);
    }

Answer 1

将光标分配给 c 后，放置 c.moveToFirst(); 将其移动到行中的第一个元素。

所以，你将拥有

Cursor c = db.rawQuery(
            "SELECT * FROM History_List ORDER BY _id desc limit 1",
            null);
c.moveToFirst();