Wrap the string in "[]" and then use the JSON parser of your choice.

For such a trivial example, it's pretty easy to produce a poorly-formed JSON String of your content and let JSONObject patch it up.

In a single expression:

new JSONObject(String.format("{%s}", str.replaceAll("([^,]+),([^,]+)(,|$)", "$1:$2,")))
// {"art":0,"comedy":0,"action":0,"crime":0,"animals":0}

If you really want to keep the 0.0 as Strings:

new JSONObject(String.format("{%s}", str.replaceAll("([^,]+),([^,]+)(,|$)", "$1:\"$2\",")))
// {"art":"0.0","comedy":"0.0","action":"0.0","crime":"0.0","animals":"0.0"}

If you want to account for possible extraneous whitespaces:

new JSONObject(String.format("{%s}", str.replaceAll("([^,]+)\\s*?,\\s*?([^,]+)(,|$)", "$1:$2,")))

.. will work with inputs like "art, 0.0, comedy, 0.0, action, 0.0, crime, 0.0, animals, 0.0" and other cases.

Disclaimer: it's not crazy-sexy code but drop in a one-line comment and it could be reasonable so long as the data structure stays simplistic.

If you don't care about the order of the object members:

$ perl -CO -MJSON::PP -l -0777 -ne '
  $j = decode_json($_);
  print join ",", map("$_=$j->{$_}", keys %$j)' your-file
var3=789,var2=456,var1=123

perl comes pre-installed on most systems, and JSON::PP is one its built-in modules.

Or if your system has python3:

PYTHONIOENCODING=utf-8 python3 -c '
import json, sys;
_ = json.load(sys.stdin);
print(",".join(map(lambda i: "%s=%s" % i, _.items())))' < your-file

(the order should be preserved as python3's dictionaries contrary to perl's hashes do keep track of an order of keys).

With a less tamed input such as:

{
  "var-\"ⓧ\"": 1e-2,
  "var=v,v": "\n",
  "var\uD83E\uDDD9": null
}

They give

var=v,v=
,var-"ⓧ"=0.01,var=

And

var-"ⓧ"=0.01,var=v,v=
,var=None

Respectively, while mlr --ijson cat gives:

var-"ⓧ"=1e-2,var=v,v=
,var=null

And jq -r 'to_entries|map("\(.key)=\(.value)")|join(",")' gives:

var-"ⓧ"=0.01,var=v,v=
,var=null

(though neither jq nor mlr are generally installed by default).

Either write a simple method yourself, or use one of the various utilities out there.

Personally I use apache StringUtils (StringUtils.join)

edit: in Java 8, you don't need this at all anymore:

String joined = String.join(",", name);

Simple:

var data = [{"name":"Marine Lines","location_id":3},{"name":"Ghatkopar","location_id":2}]
var result = data.map(function(val) {
  return val.location_id;
}).join(',');

console.log(result)

I assume you wanted a string, hence the .join(','), if you want an array simply remove that part.