Using Google GSON to convert String to JSON Array

Question

I am using the Google GSON library to convert an ArrayList of countries into JSON:

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

// arraylist gts populated

Gson gson = new Gson();
String json = gson.toJson(countries);

Which yields:

["AFGHANISTAN","ALBANIA","ALGERIA","ANDORRA","ANGOLA","ANGUILLA","ANTARCTICA","ANTIGUA AND BARBUDA","ARGENTINA","ARMENIA","ARUBA","ASHMORE AND CARTIER ISLANDS","AUSTRALIA","AUSTRIA","AZERBAIJAN"]

How can I modify my code to generate a JSON Array? For example:

[  
   {  
      "AFGHANISTAN",
      "ALBANIA",
      "ALGERIA",
      "ANDORRA",
      "ANGOLA",
      "ANGUILLA",
      "ANTARCTICA",
      "ANTIGUA AND BARBUDA",
      "ARGENTINA",
      "ARMENIA",
      "ARUBA",
      "ASHMORE AND CARTIER ISLANDS",
      "AUSTRALIA",
      "AUSTRIA",
      "AZERBAIJAN"
   }
]

Thanks!

Here is the code that my Java client uses to parse web service responses that already contain the curly-braces. This is why I want the countries response to contain the curly braces:

Gson gson = new GsonBuilder().create();
    ArrayList<Map<String, String>> myList = gson.fromJson(result,
            new TypeToken<ArrayList<HashMap<String, String>>>() {
            }.getType());

    List<Values> list = new ArrayList<Values>();

    for (Map<String, String> m : myList) {
        list.add(new Values(m.get(attribute)));
    }

[{"AFGHANISTAN","ALBANIA","ALGERIA","ANDORRA","ANGOLA","ANGUILLA","ANTARCTICA","ANTIGUA AND BARBUDA","ARGENTINA","ARMENIA","ARUBA","ASHMORE AND CARTIER ISLANDS","AUSTRALIA","AUSTRIA","AZERBAIJAN"}] isn't JSON. — Denys Séguret
– Denys Séguret, Commented Dec 21, 2012 at 15:00
I'm just trying to get the original format ["AFGHANISTAN","ALBANIA","ALGERIA"] into a new format with the curly braces: [{"AFGHANISTAN","ALBANIA","ALGERIA"}], regardless of it not being JSON. — littleK
– littleK, Commented Dec 21, 2012 at 15:26

Denys Séguret · Accepted Answer · 2012-12-21 15:33:03Z

3

To build the string you show us, which isn't JSON at all, you may do this :

StringBuilder sb = new StringBuilder("[{");
for (int i=0; i<countries.size(); i++) {
    sb.append("\"").append(countries.get(i)).append("\"");
    if (i<countries.size()-1) sb.append(",");
}
sb.append("}]");
String theString = sb.toString();

I'd recommend not trying to use Gson, which is only dedicated to JSON.

answered Dec 21, 2012 at 15:33

Denys Séguret

384k90 gold badges813 silver badges780 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Nathan Hughes · Accepted Answer · 2012-12-21 15:36:31Z

1

Using curly-braces is not a "style", it is how JSON denotes an object. square brackets represent a list, and curly-braces are used to represent an object, which in Javascript behaves like a map. Putting curly braces around the list entries is nonsensical because within the object you need name-value pairs (just like a map).

answered Dec 21, 2012 at 15:36

Nathan Hughes

96.7k21 gold badges193 silver badges288 bronze badges

1 Comment

littleK Over a year ago

Thanks, I was confused. You're right, I will either need to modify my web service to generate name-value pairs with curly-braces (which doesn't make sense for just a list of countries), or just add a special case to my java client to parse the JSON (what I have currently). I appreciate your help.

Javali · Accepted Answer · 2012-12-21 15:25:43Z

1

A simple text-representation of an array in JSON is exactly what Gson returns. What for do you need that curly-braces style?

answered Dec 21, 2012 at 15:25

Javali

5944 silver badges14 bronze badges

1 Comment

littleK Over a year ago

I have several web services that return responses with the curly-braces style, so my Java client is set up to parse responses with the curly-braces. Now, I have a new web service that is using GSON and returning a response without curly-braces. I want to modify that code (shown above) to add curly braces, so that my Java client can parse it. I don't want to modify my Java client to parse different response formats.

Collectives™ on Stack Overflow

Using Google GSON to convert String to JSON Array

3 Answers 3

Comments

1 Comment

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related