Send more then one arraylist from servlet to Android application

Question

i have three array list and i need to send it from servlet to android device....I have searched the similar problem here but i could not understand how do i retrieve all three Array List seperately. Here is servlet code:

.....
ArrayList<String> List1 = new ArrayList<String>();
ArrayList<String> List2 = new ArrayList<String>();
ArrayList<String> List3 = new ArrayList<String>();
public void doPost(HttpServletRequest req, HttpServletResponse res)
        throws ServletException, IOException {
list1.add("item1.1");
list1.add("item1.2");
list1.add("item1.3");


list2.add("item2.1");
list2.add("item2.2");
list2.add("item2.3");

list3.add("item3.1");
list3.add("item3.2");
list3.add("item3.3");

String json1 = new Gson().toJson(list1);
String json2 = new Gson().toJson(list2);
String json3 = new Gson().toJson(list3);

res.setContentType("application/json");
res.setCharacterEncoding("UTF-8");

res.getWriter().write(json1);
res.getWriter().write(json2);
res.getWriter().write(json3);
 }

Now please help me to show android side coding....or give some hint or link. Thanks.

hemu · Accepted Answer · 2013-04-30 07:53:53Z

1

Rather than converting each List into JSON, create a Map of key as string and value as list of items as follow:

Map<String, ArrayList<String>> listMap = new HashMap<String, ArrayList<String>>();
listMap.put("json1", list1);
listMap.put("json2", list2);
listMap.put("json3", list3);

String finalJSON = new Gson().toJson(listMap);

The resulting JSON will be :

{
    "json1": [
        "item1.1",
        "item1.2",
        "item1.3"
    ],
    "json2": [
        "item2.1",
        "item2.2",
        "item2.3"
    ],
    "json3": [
        "item3.1",
        "item3.2",
        "item3.3"
    ]
}

Now on Android side, create POJO representing your servlet's json string response. And using gson parse the JSON string into the POJO.

EDIT :: On Android side use :

Map<String, ArrayList<String>> map = new Gson().fromJson(finalJSON, Map.class);

edited Apr 30, 2013 at 7:53

answered Apr 30, 2013 at 6:31

hemu

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2 Comments

aseem Over a year ago

Thanks for the help....this is good way. But i am first time using JSON can you please help me how to parse JSON back to three ArrayList as they were in servlet. Or any link please.!!!

hemu Over a year ago

@aseem - You are welcome. And I am just another programmer like you..not "sir"...Also If the answer works for you than you can mark it as accept

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