liferay messageboard link to first/last message in thread - liferay

Question

i need to add a link to the first/last post/message to each message. at the moment there is a "Top" link that jumps to begin of page. i want it to jump to first post and an additional link "bottom" that jumps to last post of thread.
Adding the links is not the problem but is there a easy way to get the last message of a thread?

Answer 1

i got it:
because i need also a link to first message i created a more general private method that is called by 2 public methods (getLastMessageOfThread and ...):
private Long getMessageOfThread(long threadId, boolean last) {
Long result = null;
try {
List<MBMessage> threadMessages = MBMessageLocalServiceUtil.getThreadMessages(threadId, 0, messageCreateDateComp);
if (Validator.isNotNull(threadMessages)) {
result = last ? threadMessages.get(threadMessages.size() - 1).getMessageId() : threadMessages.get(0).getMessageId();
}
} catch (SystemException e) {
throw new IllegalStateException("Problem on getting thread messages for thread id " + threadId + ", cause:", e);
}
return result;
}
Then i hooked view_thread_message.jsp:
...
<ul class="edit-controls lfr-component">
<%
String firstMessageId = String.valueOf(MyMessageboardLocalServiceUtil.getFirstMessageOfThread(thread.getThreadId()));
String lastMessageId = String.valueOf(MyMessageboardLocalServiceUtil.getLastMessageOfThread(thread.getThreadId()));
String firstMessageAnchor ="#" + renderResponse.getNamespace() + "message_" + firstMessageId;
String lastMessageAnchor ="#" + renderResponse.getNamespace() + "message_" + lastMessageId;
%>
<liferay-portlet:renderURL varImpl="lastMessageUrl">
<portlet:param name="struts_action" value="/message_boards/view_message" />
<portlet:param name="messageId" value="<%= lastMessageId %>" />
</liferay-portlet:renderURL>
<liferay-portlet:renderURL varImpl="firstMessageUrl">
<portlet:param name="struts_action" value="/message_boards/view_message" />
<portlet:param name="messageId" value="<%= firstMessageId %>" />
</liferay-portlet:renderURL>
<li>
<liferay-ui:icon
image="top"
label="<%= true %>"
url="<%= firstMessageUrl.toString() + firstMessageAnchor %>"
/>
</li>
<li>
<liferay-ui:icon
image="bottom"
label="<%= true %>"
url="<%= lastMessageUrl.toString() + lastMessageAnchor %>"
/>
</li>
...
probably it could be don easier but i'am an absolute liferay noob. and for the sake of completeness here the used comparator:
private static class MBMessageDateComparator implements Comparator<MBMessage> {
#Override
public int compare(MBMessage arg0, MBMessage arg1) {
Long time0 = arg0.getCreateDate().getTime();
Long time1 = arg0.getCreateDate().getTime();
return time0.compareTo(time1);
}
}
Assuming that the first message has the smallest time stamp (seems to be a correct assumption).