JSON setFloat issue?

Hi. Does anybody already get this problem? I'm trying to put a float in a Json with

  JSONObject item;
  item=new JSONObject();
  float tmp=95.7;
  item.setFloat("j9T3", tmp) ;

And for output, i got "items": [{ "alb7r": 1, "name": "", "code": "", "j9T3": 95.69999694824219 }],

??? What's up?

How to write 96.7 in my Json???

Thanks for reading and answers...


  • @GoToLoop: must admit I was also initially surprised that setFloat() results in numerical inaccuracy...

    @LiveElectonics: the cause is that internally Processing first converts the float to a double:

    public JSONObject setFloat(String key, float value) {
        this.put(key, new Double(value));
        return this;

    This is what creates the 'inaccuracy' - run this sketch and you'll see:

    float tmp=95.7;
    Double foo = new Double(tmp);

    Like all such inaccuracies this generally isn't a major problem; since internally all your code is subject to them. Having said that if you're writing the JSON file to a server to then be served to web clients and you have a lot of floats in there I'd also be frustrated by this; as it will increase the file size unnecessarily :/

    In that case:

    957/10 = 95.7

  • edited December 2015 Answer ✓

    Here's a wishful fix. But the evil side of private members are showing their ugly faces once more: X(


    JSONObject item = new JSONObject() {
      public JSONObject setDouble(String key, double value) {
        put(key, new Double(value)); // not visible!!!
        return this;
    double val = 95.7d;
    item.setDouble("j9T3", val);

    That's why for a project such as Processing, classes shouldn't use private but rather protected.
    So it allows those who needs to tweak or introduce new functionalities into existing APIs. :-B

  • Thanks for your answers and solutions. Cheers

  • @goToLoop : I'm confused about your solution. How to use the put method if it's not visible ? must i tweak environement files?

  • also, it's said that all classes are public in processing... Sorry for these noob questions but i'm starting java and processing language

  • Ok the method already exist... :) just need to use it with a correct double value. Cheers

  • edited December 2015

    Ok the method already exist...

    My! I didn't know setDouble() existed already. It wasn't in the reference and I didn't care to look for it straight from the source! #-o

    Above was just my attempt to create setDouble() unbeknownst it was already there! X_X

    I believe you've already realized that. But for precaution I'm gonna reiterate it below:
    In order for setDouble() to work, either pass a double variable to it or suffix all literal values w/ d.
    Like this 1 for example: 95.7d or 957e-1d. :-B

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