using the FOR loop to catch mutliples of the same number

Question

I have a String that holds the value of an ID number from a query that I am parsing into an Integer. I need a FOR loop that checks everytime a certian number appears in the query more than five times. I am displaying this imformation on a JSP page. So far I have:

while (rs1.next()){
            String TicketNumber = rs1.getString("XXXXX_XXXXX_NO");
            String MUID = rs1.getString("XXXXXX_XXXX");
            String Name = rs1.getString("XXXXXXX_XXXXX_NAME");
            String LastName = rs1.getString("XXXXX_XXXX_NAME");
            int PIDM = Integer.parseInt(MUID);
       for ( int n = 0, n >= 5, n += 1 )

rs1 is the statment that I am quering and I am setting these values, parsing out the MIUD into PIDM but I am not quite sure wher eto go from there. Any help would be greatly appreciated. Thanks

Answer 1

Use a Map to count the number of times each number appears.

Map<Integer,Integer> map = new HashMap<Integer,Integer>()

Do this for every record in the result set

Integer count = map.get(PIDM);
if( count == null )
    map.put(PIDM, 1);
else
    map.put(PIDM, count + 1);

Then, after the query is done, loop through looking for a count of 5 or greater

for( Map.Entry<Integer,Integer> e : map.entrySet() )
{
    if( e.getValue() > 5 )
    {
        // do something with e.getKey() which is the PIDM from above
    }
}

Answer 2

Just make use of the powerful aggregate functions the SQL offers you on that area:

SELECT muid, COUNT(muid) AS muid_count FROM ticket GROUP BY muid

in combination with

Integer muid = resultSet.getInt("muid");
Integer muidCount = resultSet.getInt("muid_count");

Or if you're actually interested in the non-aggregated information, then best is indeed to use a Map<Integer, Integer> or maybe better Map<Integer, List<Ticket>> so that you can just display it in JSP at once nicely using JSTL c:forEach. You can then get the size of List<Ticket> using JSTL fn:length.

E.g.

<c:forEach items="${ticketMap}" var="ticketEntry">
    MUID: ${ticketEntry.key}<br>
    Ticket count: ${fn:length(ticketEntry.value)}<br>
    All tickets:<br>
    <c:forEach items="${ticketEntry.value}" var="ticket">
        Number: ${ticket.number}<br>
        Name: ${ticket.name}<br>
        Lastname: ${ticket.lastName}<br>
    </c:forEach>
    <hr>
</c:forEach>