Java Micro Edition(J2ME)-使用记录存储枚举更新记录

问题描述

我有一个记录存储项，其中包含(名称，数量，所有者，状态)

I have a record store of items which have (name, quantity, owner, status)

现在，当用户触发事件时，我想使用已购买"设置RecordStore中所有项目的状态

Now when the user triggers an event I want to set the status of all items in my RecordStore with "purchased"

        re = shoppingListStore.enumerateRecords(null, null, false);

        while (re.hasNextElement())
        {
            // read current values of item
            byte [] itemRecord = re.nextRecord();
            // deserialise byte array
            newItemObject.fromByteArray(itemRecord);
            // set item status to purchased
            newItemObject.setItemStatus("Purchased");
            // create new bytearray and call newitemobject . tobytearray
            //   method to return a byte array of the objects
            //   (using UTF8 encoded strings~)
            byte[] itemData = newItemObject.toByteArray();

            // add new byte array to shoppinglist store

            shoppingListStore.setRecord(re.nextRecordId(), itemData, 0, itemData.length);
        }

但是，我正在覆盖下一个记录(使用nextRecordId).我已经尝试过使用nextRecordId - 1，但是显然这在第一个范围内是不可行的

However I am overwriting the next record (using the nextRecordId). I've tried using nextRecordId - 1 but obviously this is out of bounds on the first one

希望您能提供帮助吗?

推荐答案

您尝试过吗?

re = shoppingListStore.enumerateRecords(null, null, false);

while (re.hasNextElement())
{
    int id = re.nextRecordId();
    // read current values of item
    byte [] itemRecord = shoppingListStore.getRecord(id);
    // deserialise byte array
    newItemObject.fromByteArray(itemRecord);
    // set item status to purchased
    newItemObject.setItemStatus("Purchased");
    // create new bytearray and call newitemobject . tobytearray method to return a byte array of the object (using UTF8 encoded strings~)
    byte[] itemData = newItemObject.toByteArray();

    // update shoppinglist store record with new byte array
    shoppingListStore.setRecord(id, itemData, 0, itemData.length);
}

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