NumberFormatException when parsin JSON String to Java Double

Question

I am working on currency converter and trying to parse currencies from JSON String to double. As I explored, its issue with double quotes in JSON code, but I get this JSON from banks API and it can not be changed. I tried to use solution from another old question but it did not work (double vrijednostOne = Double.parseDouble(arr.getJSONObject(indexOne).getString("Srednji za devize"));) Is there any solution to parse JSON with double quotes to double?

btnPreracunaj.addActionListener(evtRacunaj -> {
 //JSON Array - adds String input from StringBuilder
 try {
  arr = new JSONArray(response.toString());

  int indexOne = comboOne.getSelectedIndex();
  int indexTwo = comboTwo.getSelectedIndex();

  String valutaOne = arr.getJSONObject(indexOne).getString("Valuta");
  double vrijednostOne = Double.parseDouble(arr.getJSONObject(indexOne).getString("Srednji za devize"));
  String valutaTwo = arr.getJSONObject(indexTwo).getString("Valuta");
  double vrijednostTwo = Double.parseDouble(arr.getJSONObject(indexTwo).getString("Srednji za devize"));

  System.out.println(valutaOne);
  System.out.println(vrijednostOne);
  System.out.println(valutaTwo);
  System.out.println(vrijednostTwo);
 } catch (JSONException e1) {
  e1.printStackTrace();
 }
});

There is JSON from API:

[
  {
    "Broj tečajnice": "190",
    "Datum primjene": "03.10.2018",
    "Država": "Australija",
    "Šifra valute": "036",
    "Valuta": "AUD",
    "Jedinica": 1,
    "Kupovni za devize": "4,612753",
    "Srednji za devize": "4,626633",
    "Prodajni za devize": "4,640513"
  }
]

And this is exception:

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "4,626633"
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2043)
at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
at java.lang.Double.parseDouble(Double.java:538)
at Converter.lambda$0(Converter.java:136)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
...

Croatia (as well as many other European countries) uses decimal comma where English (and consequently Java's `parseDouble`) uses decimal point. Consult [Best way to parseDouble with comma as decimal separator?](https://stackoverflow.com/questions/4323599/best-way-to-parsedouble-with-comma-as-decimal-separator) to see how to handle this. — Amadan, Oct 03 '18 at 10:31
Not very great idea, but you may to replace comma with dot. Just retrieve string value, call stringValue.replace(",", ".") and then parse to double — Limmy, Oct 03 '18 at 10:34

score 2 · Answer 1 · answered Oct 03 '18 at 10:54

Since the currency prices seems to use a local format you need to use a number formatter with your locale (or rather the banks local)

NumberFormat format = NumberFormat.getInstance(new Locale("hr","HR"));
double price = format.parse(arr.getJSONObject(indexOne).getString("Srednji za devize"));

Based on a comment I used Croation as the locale but look here for a complete list of locales.

score 2 · Accepted Answer · answered Oct 03 '18 at 10:56

You can look the answer in below link. It uses locale to convert the string having ',' instead of '.' into double. the parse error is because Parsing string to double expect the decimal points in currency.

Converting different countrys currency to double using java

score -1 · Answer 3 · answered Oct 03 '18 at 10:46

-1

You can have a method:

currency = currency.substring(1, currency.length()-1);
double mainCurrency = Double.ParseDouble(currency);

answered Oct 03 '18 at 10:46

Gauravsa

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It gives a string between 1 and last character and then parses to double. – Gauravsa Oct 03 '18 at 11:54
But double quotes is not the problem here so you are removing first and last digit. – Joakim Danielson Oct 03 '18 at 11:56

NumberFormatException when parsin JSON String to Java Double

3 Answers3