Question

I have a String like the following:

"The answer is 1000"

I want to insert commas into the number 1000 without destroying the rest of the String.

NOTE: I also want to use this for other Strings of differing lengths, so substring(int index) would not be advised for getting the number.

The best way that I can think of is to use a regex command, but I have no idea how.

Thanks in advance!

Answer 1

The following formats all the non-decimal numbers:

public String formatNumbers(String input) {
  Pattern p = Pattern.compile("\\d+");
  Matcher m = p.matcher(input);
  NumberFormat nf = NumberFormat.getInstance();        
  StringBuffer sb = new StringBuffer();
  while(m.find()) {
    String g = m.group();
    m.appendReplacement(sb, nf.format(Double.parseDouble(g)));            
  }
  return m.appendTail(sb).toString();
}

e.g. if you call: formatNumbers("The answer is 1000 1000000")

Result is: "The answer is 1,000 1,000,000"

See: NumberFormat and Matcher.appendReplacement().