You would probably do this automatically with some library. But I am new with Java and JSON and I need a quick sollution.

What I would like is to write down (echo) JSON out of a JSP file. So far so good, but now I have a list of objects. So I start a fast enumeration.

And now the question: how do I close the JSON array with }] instead of ,? Normally I put a nill or null in the and.

Here is my loop:

 "rides":[{  
<% 
List<Ride> rides = (List<Ride>)request.getAttribute("matchingRides");
            for (Ride ride : rides) { 
%>               
 "ride":{     
     "rideId":"<%= String.valueOf(ride.getId()) %>",
   "freeText":"<%= freeText %>" 
   },                      

     <% 
     }
     %>   
}  ]    

You would probably do this automatically with some library. But I am new with Java and JSON and I need a quick sollution.

What I would like is to write down (echo) JSON out of a JSP file. So far so good, but now I have a list of objects. So I start a fast enumeration.

And now the question: how do I close the JSON array with }] instead of ,? Normally I put a nill or null in the and.

Here is my loop:

 "rides":[{  
<% 
List<Ride> rides = (List<Ride>)request.getAttribute("matchingRides");
            for (Ride ride : rides) { 
%>               
 "ride":{     
     "rideId":"<%= String.valueOf(ride.getId()) %>",
   "freeText":"<%= freeText %>" 
   },                      

     <% 
     }
     %>   
}  ]    

• java
• javascript
• arrays
• json
• list

Share Improve this question Follow edited Oct 15, 2010 at 15:53 BalusC 1.1m376376 gold badges3.7k3.7k silver badges3.6k3.6k bronze badges asked Oct 15, 2010 at 15:51 Christian LoncleChristian Loncle 1,58433 gold badges2020 silver badges3030 bronze badges

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2 Answers 2

Sorted by: Reset to default 5

1.) Download and setup GSON in your application container.
2.)

GSON gson = new GSON();
<%= gson.toJson( rides ) %>;

You'll save yourself time in the short run and long run if you avoid the path of insanity.

Iterate using an Iterator instead. This way you can check at end of the loop if Iterator#hasNext() returns true and then print the ,.

// Print start of array.
Iterator<Ride> iter = rides.iterator();
while (iter.hasNext()) { 
    Ride ride = iter.next();
    // Print ride.

    if (iter.hasNext()) {
       // Print ma.
    }
}
// Print end of array.

Regardless, I strongly remend to use a JSON serializer for this instead of fiddling low level like that. One of my favourites is Google Gson. Just download and drop the JAR in /WEB-INF/lib. This way you can end up with the following in the servlet:

request.setAttribute("matchingRides", new Gson().toJson(matchingRides));

and the following in JSP:

${matchingRides}

or with the old fashioned scriptlet as in your question:

<%= request.getAttribute("matchingRides") %>