How to pass arraylist from servlet to javascript?

Question

I'm passing an arraylist from servlet by setting it in the attribute and forwarding it to the jsp

Servlet:

ArrayList <String> mylist = new ArrayList <String>();

mylist.add("Superman");

mylist.add("batman");

mylist.add("flash");

request.setAttribute("mylist", mylist);

request.getRequestDispatcher("Welcome.jsp").forward(request, response);
response.sendRedirect("Index.jsp");

Index.jsp

function doPopulateList(obj)
    {

     alert("HELLO"+obj.id +obj.name+obj.value);
     var select = document.getElementsByClassName("my_dropdown1"); 
     alert("all good");
     //var list = new Array();
      var list = '${mylist}'; 
      //var options = ["1", "2", "3", "4", "5"]; 

     alert("All good till arraylist");
     for(var i=0;i<list.length;i++)
         {

         alert(list[i]);

         }

When I'm trying put the arraylist values in the alert box, I'm getting alerts like

[
S
U

I want the alerts to be like

Superman
batman
flash

Pardon me if this is duplicate question.

Ooops wrong place.

LongHike
– LongHike

2017-06-21 14:01:55 +00:00
Commented Jun 21, 2017 at 14:01 — LongHike
– LongHike, Commented Jun 21, 2017 at 14:01

Gurkan Yesilyurt · Accepted Answer · 2017-06-21 16:44:22Z

2

Firstly, you need to traverse the server-side list and add each element to JS array before the servlet does not send the response to the client.

So, this might work:

<script>
   var list = [
      <c:forEach items="${mylist}" var="hero">
        '<c:out value="${hero}" />',  
      </c:forEach>
   ];
   console.log(list);
</script>

answered Jun 21, 2017 at 16:44

Gurkan Yesilyurt

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Comments

LongHike · Accepted Answer · 2017-06-21 14:03:32Z

0

What's arriving on the client side is not an array but a string. Therefore if you loop you are looping the single characters of the String.

You need to convert the string to a JSON-Object in order to be able to loop the list items.

var list = JSON.parse('${mylist}');

answered Jun 21, 2017 at 14:03

LongHike

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2 Comments

Zeus07 Over a year ago

How do I traverse through the JSON object? I'm sorry for asking this but I've no idea about JSON.

LongHike Over a year ago

Sorry, it took so long. I was away from the computer. What you actually get is an array. I misnamed it object. Just do your regular for-loop in javascript.

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