Javajson

JSON support

Play includes the Jackson library as a dependency (A good tutorial of Jackson can be found here). What this means in practice is that one can serialize from and to JSON format.

Render JSON

As for rendering JSON, there is a helper method play.json.Render.toJson that can be used to send JSON as a response. For example:

import play.*;
import play.mvc.*;
import static play.libs.Json.toJson;

import java.util.Map;
import java.util.HashMap;

public class MyController extends Controller {
  
  public static Result index() {
    Map<String,String> d = new HashMap<String,String>();
    d.put("peter","foo");
    d.put("yay","value");
    return ok(toJson(d));
   }   
}

Google Guava

The code above can be rewritten for brevity using the Google Guava collections library:

import com.google.common.collect.ImmutableMap;
import play.*;
import play.mvc.*;
import static play.libs.Json.toJson;

public class MyController extends Controller {
  
  public static Result index() {
    return ok(toJson(ImmutableMap.of(
        "peter", "foo",
        "yay", "value")));
   }
}