processing JSONArray, JSONObject

Question

I am having the following code:

JSONObject json;
int max;
void setup() {
  size(500,500);

JSONObject json = loadJSONObject("january_2016.json");
JSONObject maxTemperature = json.getJSONObject("Max Temperature");
int max = maxTemperature.getInt("max");

  print(max);
}

void draw(){

  ellipse(max, 10, 100, 100);
}

And my Json file:

[
  {
    "Max Temperature": {
      "max": "18", 
      "avg": "6", 
      "min": "-2"
    }
]

When I run the code now I get the following error:
JSONObject must begin with {

I understood that because of the [ ] I need to use JSONArray but if I change
JSONObject json = loadJSONObject("january_2016.json");<br>
to JSONArray, I get this error:
The method getJSONObject(int) in the type JSONArray is not applicable for the arguments (String)

I am sure it must be simple but I am a pretty new to this, so thanks in advance

Possible duplicate of JSONObject text must begin with '{'

Tuvia
– Tuvia

2016-04-19 17:53:00 +00:00
Commented Apr 19, 2016 at 17:53 — Tuvia
– Tuvia, Commented Apr 19, 2016 at 17:53
I do not understand what you mean, can you clarify?

malina
– malina

2016-04-19 17:53:39 +00:00
Commented Apr 19, 2016 at 17:53 — malina
– malina, Commented Apr 19, 2016 at 17:53

Kevin Workman · Accepted Answer · 2016-04-19 18:36:51Z

I think you're misunderstanding some basics about how JSON and Processing both work.

Let's look at some example JSON. A JSONObject is a set of key/value pairs surrounded by curly brackets {}. Here is a JSONObject:

{
   "max": "18", 
   "avg": "6", 
   "min": "-2"
}

If you have a JSONObject, then you can get values by their String keys.

You can also nest JSONObjects so that a JSONObject contains a key whose value is itself a JSONObject. Like so:

{
   "Max Temperature":  {
      "max": "18", 
      "avg": "6", 
      "min": "-2"
   }
}

You can also have a JSONArray instead of a JSONObject. A JSONArray is a set of values surrounded by square brackets [] Here is a JSONArray:

 [
   {
     "id": 0,
     "species": "Capra hircus",
     "name": "Goat"
   },
   {
     "id": 1,
     "species": "Panthera pardus",
     "name": "Leopard"
   },
   {
     "id": 2,
     "species": "Equus zebra",
     "name": "Zebra"
   }
 ]

This example JSONArray is taken from the reference, and it contains 3 JSONObjects.

If you have a JSONArray, then you have to get the values from a specific index.

Now let's look at your JSON:

[
  {
    "Max Temperature": {
      "max": "18", 
      "avg": "6", 
      "min": "-2"
    }
]

Your JSON starts with a square bracket [, which means it's a JSONArray.

JSONArray jsonArray = loadJSONArray("january_2016.json");

Okay, so now you have your JSONArray. That means you have to access the data via a specific int index. In your case you only have one index, so it's index 0:

JSONObject jsonObject = jsonArray.getJSONObject(0);

The jsonObject variable now contains this JSON:

{
"Max Temperature": {
  "max": "18", 
  "avg": "6", 
  "min": "-2"
}

From here you should be able to parse the JSONObject using the functions I showed you in your other question.

You might also just modify your JSON file so that you can use it as a JSONObject directly.

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