How do I read a 2D array from jQuery in a Java Servlet?

Question

I want to send arbitrarily complex array data to a Java servlet, but have no idea how to read it on the servlet side. Here is the client side:

var data = {
  name : 'Jack',
  age  : 30,
  info : [ [1,2] , [3,4] , [5,6] ],
  info2: [1,2,3]
}

$.ajax({
  url: someURL,
  data: data,
  success: function(resp) { console.log(resp); }
});

I know I can use JSON.stringify and then parse it out on the server side, but for the sake of this question, I can't change the front end code. How do I read the "info" variable on the server side using the HttpServletRequest object? I also know you can do something like this for single arrays:

String[] info2 = request.getParameterValues("info2[]");

But this doesn't work with 2D arrays or more complicated arrays.

Any ideas?

Ravi K Thapliyal · Accepted Answer · 2015-09-28 16:52:59Z

2

If info is known to be a fixed-length array

private static final int INFO_LEN = 3;

You can collect its values inside your servlet as

String[][] info = new String[INFO_LEN][];

for (int i = 0; i < info.length; i++) {
    info[i] = request.getParameterValues("info["+i+"][]");
}

If the length is not known beforehand, collect the values in a loop until you get a null.

answered Sep 28, 2015 at 16:52

Ravi K Thapliyal

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3 Comments

user439299 Over a year ago

Hey this worked! Thanks. I thought I tried this, but I think I used Integer instead of String for my info 2D array. This was only giving me the first item in the sub-list.

Ravi K Thapliyal Over a year ago

Glad to know this helped.

Harshvardhan Solanki Over a year ago

I have a similar question. The only difference is that my 2d array index are of String type. Like this: info : [["property","one"],["class","name"]] How can I retrieve this info array contents in servlet using request object then?

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