How can I insert commas in number strings to separate the zeros?

Question

public class test
{
    public static void main(String[] args)
    {
        String abra = "100000";
        abra = abra.replace(abra.substring(abra.length() - 3),
               "," + abra.substring(abra.length() - 3));
        System.out.println(abra);
     }
}

Totally new to java and i'm trying to replace a number with comma to separate the zeros by three. It works fine for thousands and ten thousands, but i'm getting wierd results for more. Any ideas?

Thanks in advance!

Use [`NumberFormat`](https://docs.oracle.com/javase/7/docs/api/java/text/NumberFormat.html). — Andy Turner, Feb 08 '16 at 13:16
Thanks alot, now please upvote this post. I've edited the questions such that it better describes the problem! — Thomas, Dec 25 '18 at 13:07

score 3 · Accepted Answer · answered Feb 08 '16 at 13:17

Because you're manually only for 6 digits. A better approach will be using NumberFormat#getNumberInstance with Locale.US:

A Locale object represents a specific geographical, political, or cultural region. An operation that requires a Locale to perform its task is called locale-sensitive and uses the Locale to tailor information for the user. For example, displaying a number is a locale-sensitive operation— the number should be formatted according to the customs and conventions of the user's native country, region, or culture.

NumberFormat.getNumberInstance(Locale.US).format(20000000);
// 20,000,000

How can I insert commas in number strings to separate the zeros?

1 Answers1