Question

public ArrayList<Chat> fetchChatHistory(String senderId, String receiverId) {
        ArrayList<Chat> chatList = new ArrayList<Chat>();
        String where = "" + DataProviderConstants.MESSAGE_RECEIVER_ID_COLUMN
                + " in (?,?) AND "
                + DataProviderConstants.MESSAGE_SENDER_ID_COLUMN + " in (?,?) "
        /*
         * +"("+DataProviderConstants.MESSAGE_RECEIVER_ID_COLUMN+"=? AND "
         * +DataProviderConstants.MESSAGE_SENDER_ID_COLUMN+"=?)"
         */;
        Cursor cursor = mContext.getContentResolver().query(
                DataProviderConstants.MESSAGE_TABLE_CONTENTURI, null, where,
                new String[] { senderId, receiverId, senderId, receiverId },
                DataProviderConstants.MESSAGE_ID_COLUMN);
        if (cursor != null && cursor.moveToFirst()) {
            do {
                Chat chat = new Chat();
                chat.setRecieverID(cursor.getString(cursor
                        .getColumnIndex(DataProviderConstants.MESSAGE_RECEIVER_ID_COLUMN)));
                chat.setSenderID(cursor.getString(cursor
                        .getColumnIndex(DataProviderConstants.MESSAGE_SENDER_ID_COLUMN)));
                chat.setMessage(cursor.getString(cursor
                        .getColumnIndex(DataProviderConstants.MSG_COLUMN)));
                chat.setLat(cursor.getString(cursor
                        .getColumnIndex(DataProviderConstants.MESSAGE_LAT_COLUMN)));
                chat.setLon(cursor.getString(cursor
                        .getColumnIndex(DataProviderConstants.MESSAGE_LON_COLUMN)));
                int isunread = cursor.getInt(cursor
                        .getColumnIndex(DataProviderConstants.MSG_IS_UNREAD));
                chat.setIsUnread((isunread == 0 ? false : true));
                chat.setDelvired(true);
                chatList.add(chat);
            } while (cursor.moveToNext());
        }
        return chatList;
    }

使用此代码可以向前方向从Sq-lite数据库获取数据，而我想要反向顺序我正在使用Collections.reverse但这里给出错误我不知道如何以反向顺序获取数据来自android中的Sq-lite有缺失有些东西请建议我或帮助我。

Answer 1

在query方法中，最后一个参数是＆＃34; orderby＆＃34;。变化

 Cursor cursor = mContext.getContentResolver().query(
                DataProviderConstants.MESSAGE_TABLE_CONTENTURI, null, where,
                new String[] { senderId, receiverId, senderId, receiverId },
                DataProviderConstants.MESSAGE_ID_COLUMN);

带

 Cursor cursor = mContext.getContentResolver().query(
                DataProviderConstants.MESSAGE_TABLE_CONTENTURI, null, where,
                new String[] { senderId, receiverId, senderId, receiverId },
                DataProviderConstants.MESSAGE_ID_COLUMN+" DESC");

这将为您提供按ID排序的行，但按降序排列。

Answer 2

这样的事情会起作用吗？

public ArrayList<Chat> fetchChatHistory(String senderId, String receiverId) {
        ArrayList<Chat> chatList = new ArrayList<Chat>();
        String where = "" + DataProviderConstants.MESSAGE_RECEIVER_ID_COLUMN
                + " in (?,?) AND "
                + DataProviderConstants.MESSAGE_SENDER_ID_COLUMN + " in (?,?) "
        /*
         * +"("+DataProviderConstants.MESSAGE_RECEIVER_ID_COLUMN+"=? AND "
         * +DataProviderConstants.MESSAGE_SENDER_ID_COLUMN+"=?)"
         */;
        Cursor cursor = mContext.getContentResolver().query(
                DataProviderConstants.MESSAGE_TABLE_CONTENTURI, null, where,
                new String[] { senderId, receiverId, senderId, receiverId },
                DataProviderConstants.MESSAGE_ID_COLUMN);
        if (cursor != null && cursor.moveToLast()) {
            do {
                Chat chat = new Chat();
                chat.setRecieverID(cursor.getString(cursor
                        .getColumnIndex(DataProviderConstants.MESSAGE_RECEIVER_ID_COLUMN)));
                chat.setSenderID(cursor.getString(cursor
                        .getColumnIndex(DataProviderConstants.MESSAGE_SENDER_ID_COLUMN)));
                chat.setMessage(cursor.getString(cursor
                        .getColumnIndex(DataProviderConstants.MSG_COLUMN)));
                chat.setLat(cursor.getString(cursor
                        .getColumnIndex(DataProviderConstants.MESSAGE_LAT_COLUMN)));
                chat.setLon(cursor.getString(cursor
                        .getColumnIndex(DataProviderConstants.MESSAGE_LON_COLUMN)));
                int isunread = cursor.getInt(cursor
                        .getColumnIndex(DataProviderConstants.MSG_IS_UNREAD));
                chat.setIsUnread((isunread == 0 ? false : true));
                chat.setDelvired(true);
                chatList.add(chat);
            } while (cursor.moveToPrevious());
        }
        return chatList;
    }

我已经改变了

cursor.moveToFirst()

到

cursor.moveToLast()

和

cursor.moveToNext()

到

cursor.moveToPrevious()

Answer 3

有两种方式 a）使用答案中定义的DESC b）反转数组chatList。就在你的行return chatList;

之前

添加此行

Collections.reverse(chatList );
return chatList ;

Answer 4

根据官方Android Documention

getContentResolver().query(
    UserDictionary.Words.CONTENT_URI,   // The content URI of the words table
    mProjection,                        // The columns to return for each row
    mSelectionClause                    // Selection criteria
    mSelectionArgs,                     // Selection criteria
    mSortOrder);

指定ORDER BY ID DESC/ASC

时请注意mSorOrder

Answer 5

只需使用原始查询。这与其他查询语言类似。

String selectQuery =“SELECT * FROM YOUR_TABLE_NAME由COLUMN_NAME DESC提供任何合作订单;”;

Cursor cursor = db.rawQuery（selectQuery，null）;

如何从Sqlite数据库以反向顺序从Sqlite获取数据

5 个答案: