CODEWITHSUNDEEP
javajavascriptjqueryplayframework
pret
pret

Reputation: 273

conversion of array list to json object string

I have a model class method which returns a list of objects which contains all the registered user details. I want to fetch the list resturned by all() method and convert the data into JSON object and pass it to the view like a string. How can I do this conversion of this array list to JSON object?

I was unable to do this by below: 

ObjectMapper mapper = new ObjectMapper();
JSONObject json = new JSONObject();
JsonNodeFactory jsonnode = JsonNodeFactory.instance;
ObjectNode result = new ObjectNode(jsonnode);
for (int i = 0; i < list.size(); i++) {
    json.put(list.get(i).fname, list.get(i));
    System.out.println(json.get("fname"));
}

@Entity
class Mydata extends Model {

    @Id
    public Long Id;
    public String fname;
    public String lname;
    public String city;
    public String state;
    /****************** READ/select OPERATION *****************/
    public static Finder < Long, Mydata > finder = new Finder(Long.class, Mydata.class);

    public static List < Mydata > all() {
        return finder.all();
    }
    public static void createuser(Mydata user) {
        user.save();
    }
}

Upvotes: 12

Views: 68015

Answers (4)

labheshr
labheshr

Reputation: 3056

have you looked at this: http://www.json.org/javadoc/org/json/JSONObject.html#valueToString(java.lang.Object)

JSONObject.valueToString(<<your list of custom object>> OR <<objects>> OR <<map>>)

works just fine...there are some other methods on that lib, if you are interested....

Upvotes: 0

Rakesh Bhalani
Rakesh Bhalani

Reputation: 678

To convert ArrayList to Json, just download Open Source json utility from: http://json.org/java/ or Jar file from here

And just do:

JSONArray jsonAraay = new JSONArray(your_array_list);

That's it

Note: You should have setter/getter in your POJO/MODEL class to convert arraylist to json

Upvotes: 19

Michael Hawkins
Michael Hawkins

Reputation: 2873

You could use all sorts of third party libraries like others here have suggested, or just use Play's own simplified methods for this (found in play.libs.Json) which works with Jackson objects, but it is integrated into the framework and requires a lot less code to use, for example:

JsonNode myJsonNode = Json.toJson(MyListObject); which converts the List to a JsonNode object, then use something like String jsonResult = Json.stringify(myJsonNode); to convert it into a string representation.

If you are using the JSON in a template, don't forget to wrap it in something like @Html(myJsonString) so it will not escape anything. Otherwise, if you are just outputting the pure JSON to the browser, a simple return ok(jsonResult); will work as Play will automatically set the content type.

Reference link: http://www.playframework.com/documentation/api/2.0/java/play/libs/Json.html

Upvotes: 0

fge
fge

Reputation: 121750

Don't bother with org.json, use Jackson all the way:

// list is a List<MyData>
final ObjectMapper mapper = new ObjectMapper();
final Map<String, MyData> map = new HashMap<>();
for (final MyData data: list)
    map.put(data.fname, data);
final JsonNode json = mapper.valueToTree(map);

Upvotes: 1

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