Use JSTL to display a Vector and skip duplicated data

Question

I have a Vector of location, which has country, state and city all as Strings. I want to display the data as: USA | texas | austin, dallas, houston... USA | californa | la, san francisco ...

What I have:

   <c:forEach items="${locations}" var="location" >
       <h4><c:out value="${location.country.name}"/></h4>
       <h4><c:out value="${location.state.name}"/></h4>
       <h4><c:out value="${location.city.name}"/></h4>
   </c:forEach>

What is the best way to skip country and state name if they are same as the last value. I am sure I can use local variables for currentCountry and currentState to not show duplicate values. I just want to know the best practice.

Thanks,

Community · Accepted Answer · 2017-05-23 12:20:50Z

3

The best and the easiest way to do that is to add you list (in this of type vector) to a set, a HashSet for instance. You can add the list of location.city.name to the set, with a loop, duplicates will be removed automatically from the set, then you display your set of cities.

 Set<String> setOfCities = new HashSet();
   for(int i = 0; i< setOfCities.size(); i++){
       setOfCities.add(location.city.name);
   }

Or if you want to add directly the list of location, which are not of type String, you have to implement the Comparator interface to be able to compare your list of locations and remove duplicate. To override the equals() method, you can look this post: https://stackoverflow.com/a/5741080/3010827

edited May 23, 2017 at 12:20

CommunityBot

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answered Aug 3, 2014 at 14:11

Amaynut

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