Best way to parseDouble with comma as decimal separator

Question

Following is resulting in an Exception   String p  1 234   Double d Double valueOf p    System out println d     Is there a better way to parse  1 234  to get 1 234 than  p   p replaceAll

User · Answer

If you don t know the correct Locale and the string can have a thousand separator this could be a last resort       doubleStrIn   doubleStrIn replaceAll      d                   if  doubleStrIn matches         d    d              return Double parseDouble doubleStrIn replaceAll            replaceAll                 if  doubleStrIn matches       d      d              return Double parseDouble doubleStrIn replaceAll                return Double parseDouble doubleStrIn replaceAll               Be aware  this will happily parse strings like  R 1 52 43 2  to  15243 2

User · Answer

Double parseDouble p replace                is very quick as it searches the underlying character array on a char-by-char basis  The string replace versions compile a RegEx to evaluate   Basically replace char char  is about 10 times quicker and since you ll be doing these kind of things in low-level code it makes sense to think about this  The Hot Spot optimiser will not figure it out    Certainly doesn t on my system

User · Answer

In the case where you don t know the locale of the string value received and it is not necessarily the same locale as the current default locale you can use this     private static double parseDouble String price       String parsedStringDouble      if  price contains       amp  amp  price contains                int indexOfComma   price indexOf               int indexOfDot   price indexOf               String beforeDigitSeparator          String afterDigitSeparator          if  indexOfComma  lt  indexOfDot               String   splittedNumber   price split                     beforeDigitSeparator   splittedNumber 0               afterDigitSeparator   splittedNumber 1                     else               String   splittedNumber   price split                   beforeDigitSeparator   splittedNumber 0               afterDigitSeparator   splittedNumber 1                     beforeDigitSeparator   beforeDigitSeparator replace          replace                   parsedStringDouble   beforeDigitSeparator     afterDigitSeparator            else           parsedStringDouble   price replace                      return Double parseDouble parsedStringDouble        It will return a double no matter what the locale of the string is  And no matter how many commas or points there are  So passing 1 000 000 54 will work so will 1 000 000 54 so you don t have to rely on the default locale for parsing the string anymore  The code isn t as optimized as it can be so any suggestions are welcome  I tried to test most of the cases to make sure it solves the problem but I am not sure it covers all  If you find a breaking value let me know

User · Answer

This is the static method I use in my own code   public static double sGetDecimalStringAnyLocaleAsDouble  String value         if  value    null            Log e  CORE    Null value             return 0 0             Locale theLocale   Locale getDefault        NumberFormat numberFormat   DecimalFormat getInstance theLocale       Number theNumber      try           theNumber   numberFormat parse value           return theNumber doubleValue          catch  ParseException e               The string value might be either 99 99 or 99 99  depending on Locale             We can deal with this safely  by forcing to be a point for the decimal separator  and then using Double valueOf               http   stackoverflow com questions 4323599 best-way-to-parsedouble-with-comma-as-decimal-separator         String valueWithDot   value replaceAll                    try             return Double valueOf valueWithDot             catch  NumberFormatException e2                    This happens if we re trying  say  to parse a string that isn t a number  as though it were a number                 If this happens  it should only be due to application logic problems                 In this case  the safest thing to do is return 0  having first fired-off a log warning              Log w  CORE    Warning  Value is not a number    value               return 0 0

User · Answer

You can use this  the French locale has   for decimal separator   NumberFormat nf   NumberFormat getInstance Locale FRANCE   nf parse p     Or you can use java text DecimalFormat and set the appropriate symbols   DecimalFormat df   new DecimalFormat    DecimalFormatSymbols symbols   new DecimalFormatSymbols    symbols setDecimalSeparator       symbols setGroupingSeparator       df setDecimalFormatSymbols symbols   df parse p

User · Answer

This would do the job   Double parseDouble p replace

User · Answer

You of course need to use the correct locale  This question will help

User · Answer

As E-Riz points out  NumberFormat parse String  parse  1 23abc  as 1 23  To take the entire input we can use   public double parseDecimal String input  throws ParseException    NumberFormat numberFormat   NumberFormat getNumberInstance Locale getDefault       ParsePosition parsePosition   new ParsePosition 0     Number number   numberFormat parse input  parsePosition      if parsePosition getIndex      input length         throw new ParseException  Invalid input   parsePosition getIndex            return number doubleValue

User · Answer

In Kotlin you can use extensions as below  fun String toDoubleEx     Double      val decimalSymbol   DecimalFormatSymbols getInstance   decimalSeparator   return if  decimalSymbol                 this replace decimalSymbol       toDouble       else         this toDouble          and you can use it everywhere in your code like this  val myNumber1    quot 5 2 quot  val myNumber2    quot 6 7 quot   val myNum1   myNumber1 toDoubleEx   val myNum2   myNumber2 toDoubleEx    It is easy and universal

User · Answer

Use java text NumberFormat  NumberFormat format   NumberFormat getInstance Locale FRANCE   Number number   format parse  quot 1 234 quot    double d   number doubleValue     Updated  To support multi-language apps use  NumberFormat format   NumberFormat getInstance Locale getDefault

[java] Best way to parseDouble with comma as decimal separator?

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