Get object list with lists from JSON with JSON.Simple

Question

I have a JSON array with arrays inside. How can i Parse this using Json.simple.

JSON Object example:

[  
   {  
      "ID":"1",
      "Objects":[  
         {  
            "ObjectID":"5"
         },
         {  
            "ObjectID":"9"
         }
      ]
   },
   {  
      "ID":"2",
      "Objects":[  
         {  
            "ObjectID":"99"
         },
         {  
            "ObjectID":"11"
         }
      ]
   }
]

Class Foo

public int ID;
public List<Obj> Objects;

Class Obj

public int ObjectID;

so i want a list of Foo but in foo the Objects need to be filled as well

So what i need is:

List<Foo> foos = .... the output from the JSON

Answer 1

Having the following classes:

public class Foo {

    private int id;
    private List<Obj> objects;

    // Getters and setters ommited
}

public class Obj {

    private int objectID;

    // Getters and setters ommited      
}

Use this piece of code to parse your JSON:

String json = "[{\"ID\":\"1\",\"Objects\":[{\"ObjectID\":\"5\"},{\"ObjectID\":\"9\"}]},{\"ID\":\"2\",\"Objects\":[{\"ObjectID\":\"99\"},{\"ObjectID\":\"11\"}]}]";
JSONParser parser = new JSONParser();
List<Foo> foos = parseFooArray((JSONArray) parser.parse(json));

That's where the magic happens:

private List<Foo> parseFooArray(JSONArray array) {

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

    for (Object item : array) {
        JSONObject object = (JSONObject) item;
        Foo foo = new Foo();
        foo.setId(Integer.valueOf((String) object.get("ID")));
        foo.setObjects(parseObjectArray((JSONArray) object.get("Objects")));
        list.add(foo);
    }

    return list;
}

private List<Obj> parseObjectArray(JSONArray array) {

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

    for (Object item : array) {
        JSONObject object = (JSONObject) item;
        Obj obj = new Obj();
        obj.setObjectID(Integer.valueOf((String) object.get("ObjectID")));
        list.add(obj);
    }

    return list;
}