If I have a number that is 100,000,000 how can I represent that as "100M" in a string?
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- This is similar, but not quite a duplicate: stackoverflow.com/questions/529432/…Aaron Novstrup– Aaron Novstrup2010-09-09 00:54:24 +00:00Commented Sep 9, 2010 at 0:54
- Here's a class that does something similar: jcs.mobile-utopia.com/jcs/5242_ScaledNumberFormat.java , unfortunately it doesn't seem to be part of a supported library.oksayt– oksayt2010-09-09 00:59:30 +00:00Commented Sep 9, 2010 at 0:59
- None of the answers consider i18n!jwl– jwl2014-01-29 22:44:57 +00:00Commented Jan 29, 2014 at 22:44
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4 Answers
To my knowledge there's no library support for abbreviating numbers, but you can easily do it yourself:
NumberFormat formatter = NumberFormat.getInstance(); String result = null; if (num % 1000000 == 0 && num != 0) { result = formatter.format(num / 1000000) + "M"; } else if (num % 1000 == 0 && num != 0) { result = formatter.format(num / 1000) + "K"; } else { result = formatter.format(num); } Of course, this assumes that you don't want to shorten a number like 1,234,567.89. If you do, then this question is a duplicate.
Comments
There is an algorithm to do that:
You need a map that looks like
2 => "hundred" 3 => "thousand" 6 => "million" 9 => "billion" 12 => "trillion" 15 => "quadrillion" ... and so on...
1) Take the number "num", calculate the log10 exponent "ex" of the number and floor it.
Attention
log10(0) doesn't exist so check that the number is not 0 and since it doesn't make sense to output something like 20 = "2 ten" you should return the number as it is if it's smaller than 100 !
2) Now iterate thru the keys of the hash map above and look if a key matches, if not take the key that is smaller than the exponent "ex".
3) Update "ex" to this key!
4) Now format the number like
num = num / pow(10, ex)
(!! ex is a key of the hash map !!)
5) now you could round the number to a certain precision and output num + yourHash[ex]
An example:
number = 12345.45 exponent = floor(log10(12345.45)) exponent should now be 4 ! look for a key in the hash map -- whoops no key matches 4 ! -- so take 3 ! set exponent to 3 now you scale the number: number = number / pow(10, exponent) number = 12345.45 / pow(10, 3) number = 12345.45 / 1000 number is now 12.34545 now you get the value to the corresponding key out of the hash map the value to the key, which is 3 in this example, is thousand so you output 12.34545 thousand 
Comments
Here's my solution to make it a little more generic:
private static final String[] magnitudes = new String[] {"", "K", "M"}; public static String shortenNumber(final Integer num) { if (num == null || num == 0) return "0"; float res = num; int i = 0; for (; i < magnitudes.length; i++) { final float sm = res / 1000; if (sm < 1) break; res = sm; } // don't use fractions if we don't have to return ( (res % (int) res < 0.1) ? String.format("%d", (int)res) : String.format("%.1f", res) ) + magnitudes[i]; } 
Comments
This is more general solution.
public static String abbreviateNumber(long num) { long temp = num / 1000000; if(temp > 0) { return temp + "M+"; } temp = num / 1000; if (temp > 0) { return temp + "K+"; } temp = num / 500; if (temp > 0) { return "500+"; } temp = num / 100; if (temp > 0) { return "100+"; } temp = num / 50; if (temp > 0) { return "50+"; } temp = num / 10; if (temp > 0) { return "10+"; } return String.valueOf(num); } 