private static void saveItem(List<EventTracker> items) {
    List<WriteRequest> wrList = new ArrayList<>();
    try {

        for (EventTracker item : items) {
            WriteRequest wreqItem;
            wreqItem = getWriteRequest(item);
            wrList.add(wreqItem);
        }

        try {

            BatchWriteItemResult batchWriteItemResult = new BatchWriteItemResult();
            do {
                BatchWriteItemRequest batchWriteItemRequest = new BatchWriteItemRequest();
                batchWriteItemRequest.addRequestItemsEntry(forumTableName, wrList);// setRequestItems(writeRequestitems);
                batchWriteItemResult = amazonDynamoDB.batchWriteItem(batchWriteItemRequest);
                // Check for unprocessed keys which could happen if you
                // exceed
                // provisioned throughput
                Map<String, List<WriteRequest>> unprocessedItems = batchWriteItemResult.getUnprocessedItems();
                if (unprocessedItems.size() == 0) {
                    System.out.println("No unprocessed items found");
                } else {
                    System.out.println("Sleeping for: " + ThreadLocalRandom.current().nextInt(500, 999 + 1));
                    Thread.sleep(ThreadLocalRandom.current().nextInt(500, 999 + 1));
                    wrList = unprocessedItems.get(forumTableName);
                    System.out.println("Retrieving the unprocessed items");
                }

            } while (batchWriteItemResult.getUnprocessedItems().size() > 0);

        } catch (Exception e) {
            System.err.println("Failed to retrieve items: ");
            e.printStackTrace(System.err);
        }

    } catch (Exception e) {

    }
}

This is what we need to know if we want to make use of batch operations to put data to a dynamo db table. Lets see the steps that need to be followed to accomplish this. In this example, we are trying to persist a list of EventTracker data, which is my POJO.

1. For each record to be inserted, we need to create a PUT Request.
2. Each PUT Request is wrapped to a Write Request.
3. All Write Request are bundled into a List.
4. The WriteRequest List is then added to the BatchWriteItemRequest and executed.

The below code will show how we create write requests.

private static WriteRequest getWriteRequest(EventTracker event) {

    WriteRequest wreq = null;// = new WriteRequest();

    if (event != null) {
        Map<String, AttributeValue> attributeMap = new HashMap<String, AttributeValue>();

        addAttribute(attributeMap, "event_id", event.getEventId());
        addAttribute(attributeMap, "created_datetime", event.getCreatedDatetime());
        addAttribute(attributeMap, "event", event.getEvent());
        addAttribute(attributeMap, "event_type", event.getEventType());
        addAttribute(attributeMap, "response_id", "NULL");

        wreq = new WriteRequest(new PutRequest(attributeMap));
    }
    return wreq;
}

private static void addAttribute(Map<String, AttributeValue> item, String attributeName, String value) {
    AttributeValue attributeValue = new AttributeValue(value);
    item.put(attributeName, attributeValue);
}