Todo tree Api json reading

json.java

import com.google.gson.JsonArray;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

import java.util.ArrayList;

/**
 * Created by Jógvan 21/05-2016 19:28.
 *
 * Using this library: http://www.java2s.com/Code/JarDownload/json-simple/json-simple-1.1.1.jar.zip
 */
public class json {

    static String jsondata = "{\n" +
            "    \"todos\": [\n" +
            "        {\n" +
            "            \"_id\": \"572c5f17e2cce1e442ff1c9c\",\n" +
            "            \"title\": \"Root!\",\n" +
            "            \"owner\": \"5729fec3b2102fdd1dd53a32\",\n" +
            "            \"__v\": 2,\n" +
            "            \"child\": [\n" +
            "                {\n" +
            "                    \"_id\": \"572c5f930b63dee544e1eabf\",\n" +
            "                    \"title\": \"Parent2!\",\n" +
            "                    \"owner\": \"5729fec3b2102fdd1dd53a32\",\n" +
            "                    \"__v\": 2,\n" +
            "                    \"child\": [\n" +
            "                        {\n" +
            "                            \"_id\": \"572c5fad5993c09c451c31a2\",\n" +
            "                            \"title\": \"Child4!\",\n" +
            "                            \"owner\": \"5729fec3b2102fdd1dd53a32\",\n" +
            "                            \"__v\": 1,\n" +
            "                            \"child\": [\n" +
            "                                {\n" +
            "                                    \"_id\": \"572c5fbb841f2a684698de1e\",\n" +
            "                                    \"title\": \"Super Child!\",\n" +
            "                                    \"owner\": \"5729fec3b2102fdd1dd53a32\",\n" +
            "                                    \"__v\": 0,\n" +
            "                                    \"child\": [],\n" +
            "                                    \"parent\": \"572c5fad5993c09c451c31a2\",\n" +
            "                                    \"root\": \"572c5f17e2cce1e442ff1c9c\",\n" +
            "                                    \"archived\": false,\n" +
            "                                    \"date\": \"2016-05-06T09:11:23.704Z\"\n" +
            "                                }\n" +
            "                            ],\n" +
            "                            \"parent\": \"572c5f930b63dee544e1eabf\",\n" +
            "                            \"root\": \"572c5f17e2cce1e442ff1c9c\",\n" +
            "                            \"archived\": false,\n" +
            "                            \"date\": \"2016-05-06T09:11:09.090Z\"\n" +
            "                        }\n" +
            "                    ],\n" +
            "                    \"parent\": \"572c5f17e2cce1e442ff1c9c\",\n" +
            "                    \"root\": \"572c5f17e2cce1e442ff1c9c\",\n" +
            "                    \"archived\": false,\n" +
            "                    \"date\": \"2016-05-06T09:10:43.367Z\"\n" +
            "                }\n" +
            "            ],\n" +
            "            \"parent\": null,\n" +
            "            \"root\": null,\n" +
            "            \"archived\": false,\n" +
            "            \"date\": \"2016-05-06T09:08:39.732Z\"\n" +
            "        },\n" +
            "        {\n" +
            "            \"_id\": \"572c760f880b964e7ac06085\",\n" +
            "            \"title\": \"Root2!\",\n" +
            "            \"owner\": \"5729fec3b2102fdd1dd53a32\",\n" +
            "            \"__v\": 1,\n" +
            "            \"child\": [],\n" +
            "            \"parent\": null,\n" +
            "            \"root\": null,\n" +
            "            \"archived\": false,\n" +
            "            \"date\": \"2016-05-06T10:46:39.187Z\"\n" +
            "        }\n" +
            "    ]\n" +
            "}";

    public static void main(String[] args) {
        new json();
    }

    public json(){
        JsonObject o = new JsonParser().parse(jsondata).getAsJsonObject();

        JsonArray roots = o.getAsJsonArray("todos");

        ArrayList<Todo> todoRoots = new ArrayList<>();
        for (int i = 0; i < roots.size(); i++) {
            todoRoots.add(build(roots.get(i).getAsJsonObject(), null));
        }

        for (Todo todo : todoRoots) {
            printTodos(todo, 0);
        }
    }

    // Print all
    public void printTodos(Todo todo, int spacing){

        for (int i = 0; i < spacing; i++) {
            System.out.print("-");
        }
        System.out.println(todo.title);

        for (Todo child : todo.children) {
            printTodos(child, spacing+1);
        }
    }

    // Load all todos
    public Todo build(JsonObject currentNode, Todo parent){
        String title = currentNode.get("title").getAsString();
        boolean achieved = currentNode.get("archived").getAsBoolean();

        Todo todo = new Todo(title, achieved, null, null);

        if(parent != null){
            todo.parent = parent;
            if(parent.root != null){
                todo.root = parent.root;
            }else {
                todo.root = parent;
            }
        }


        JsonArray children = currentNode.getAsJsonArray("child");
        for (int i = 0; i < children.size(); i++) {
            todo.children.add(build(children.get(i).getAsJsonObject(), todo));
        }

        return todo;
    }

    // Todo class
    class Todo{
        String title;
        boolean achieved;
        Todo root;
        Todo parent;
        ArrayList<Todo> children = new ArrayList<>();

        public Todo(String title, boolean achieved, Todo root, Todo parent){
            this.title = title;
            this.achieved = achieved;
            this.root = root;
            this.parent = parent;
        }
    }

}