Nullpointer exception Array

shirinmalina

Hello everybody, I am pretty new to processing, and just ran into the following problem

I am importing values from a json file, and when I run the following code I get a Nullponter Exception error. I googled and tried different things, but unfortunately I cannot solve the problem. I am greatful for any help, here is my code:

JSONObject json;
int max;
void setup() {
  size(841,594);

JSONArray jsonArray = loadJSONArray("january_2016.json");
JSONObject jsonObject = jsonArray.getJSONObject(0); 
JSONObject maxTemperature = json.getJSONObject("Max Temperature");
int max = maxTemperature.getInt("max");

  print(max);
}

void draw(){
//Max Temperature  
  textAlign(CENTER);
  text("Max Temperature",841/4, 594/2+100);

  ellipseMode(RADIUS);
  ellipse(841/4, 594/2, max, max); // max
  ellipse(841/4, 594/2, max, max); //avg
  ellipse(841/4, 594/2, max, max); //min

}

GoToLoop

It would help a lot if you had said which statement thrown the NPE. (:|
In case it was method getInt(), we can specify a default value in case of error:
https://Processing.org/reference/JSONObject_getInt_.html

shirinmalina

I don`t know what you mean with what statement. I also checked the processing references and still did not find an aswer. Any suggestions what could be the problem in my code?

TfGuy44

If you were getting a NPE, you'd know what line it was on.

On line 9 you redefine max to be a local variable. You shouldn't - this hides access to the global variable with the same name.

Change line 9 so it starts:

max = 

shirinmalina

That was already helpful! But now I am still getting an NPE on line 8

JSONObject maxTemperature = json.getJSONObject("Max Temperature");

GoToLoop

json.getJSONObject("Max Temperature");

Variable json was globally declared at the top of the sketch: JSONObject json;.
However it's never got initialized. Therefore json is still null when reaching line #8:
https://Processing.org/reference/null.html