How do I read/load a JSON formatted String

camelbob

I have a JSON formatted string that I want to load into a JSON object. I cannot read this from a file or a URL, I need to parse the string. Any help greatly appreciated.

Chrisir

https://www.processing.org/reference/loadJSONObject_.html

camelbob

Hi Chrisir, loadJSONObject() assumes you are loading the data from a file or a URL, as I said in my post I cannot use either and if you try to load a string you get the error "The function loadJSONObject(String) does not exist"

Chrisir

never mind

doesn't work

Chrisir

here...

they forgot it in the reference...

but it works similar to parseXML() I think....

;-)

// The following short JSON String is parsed 
// in the code below. 
//
String t1 = " {   \"id\": 0,   \"species\": \"Panthera leo\",   \"name\": \"Lion\" } ";

JSONObject json;

void setup() {

  // json = new JSONObject(t1); 
  // json = loadJSONObject(t1);

  json = parseJSONObject(t1);


  int id = json.getInt("id");
  String species = json.getString("species");
  String name = json.getString("name");

  println(id + ", " + species + ", " + name);
}

camelbob

I had tried that earlier and got the error "the constructor JSONObject(Object) is not visible" I am using Processing 2.0.2, I assume you are using a later version in which it is visible?

Chrisir

it's still not trivial I guess - you need to know the format of the json-string, the names of all fields and arrays......

Chrisir

It's parseJSONObject ?

Chrisir

yeah, I am on 3.0a5

camelbob

I have moved to procesing version 2.2.1 and used your example and get the same error "the constructor JSONObject(Object) is not visible" when the constructor is called json = new JSONObject(t1);

GoToLoop

Undocumented method parseJSONObject() exists in Processing 2.2.1. No need for any alpha versions! ;)
Although I think its implementation is slower than it should be to say the least: :O)

public JSONObject parseJSONObject(String input) {
  return new JSONObject(new java.io.StringReader(input));
}

Why instantiate a StringReader for a mere String?
IMO it makes more sense to directly create a JSONTokener from the String and pass it to the JSONObject: :-B

public JSONObject parseJSONObject(String input) {
  return new JSONObject(new JSONTokener(input));
}

But then we get: "The constructor JSONObject(JSONTokener) is not visible"! X(
Even worse, the JSONTokener class itself isn't public nor protected!!!
Seems like the guys messing w/ the JSON stuff aren't friendly at letting their stuff public! >:P

Most Processing's API are public or at least protected.
However this policy isn't being implemented to JSON code and it's locking us away! :-w

Chrisir

quote

when the constructor is called json = new JSONObject(t1);

as said

It's parseJSONObject !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

;-)

Chrisir

String t1 = " {   \"id\": 0,   \"species\": \"Panthera leo\",   \"name\": \"Lion\" } ";

JSONObject json;

void setup() {

  json = parseJSONObject(t1);  // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

camelbob

Thanks Chrisir, all working . Note to self, "try reading what somebody writes!"

Chrisir

that's a lesson....

but how about that... often I make a note on paper for a thing I have to do and next day I can't read it any more... because my hand-writing is too bad...

;-)