import org.json.JSONArray;
import org.json.JSONObject;

public class JSONDemo {
   public static void main(String[] args) { 
      JSONArray list = new JSONArray();

      list.put("foo");
      list.put(new Integer(100));
      list.put(new Double(1000.21));
      list.put(new Boolean(true));
      list.put(JSONObject.NULL);

      System.out.println("JSONArray: ");
      System.out.println(list);
   }
}

JSONArray: 
["foo",100,1000.21,true,null]