Lets assume we have one million.
In English it should be formatted as 1,000,000 in German it should be 1.000.000.
You can achieve this with using the NumberFormat class, this also allows you to parse Strings into a local aware number.
NumberFormat formatter = NumberFormat.getInstance(Locale.GERMAN);
String localeFormattedNumber = formatter.format(1000000);
Using NumberFormat class:
For English:
NumberFormat nf_us = NumberFormat.getInstance(Locale.US);
String number_us = nf_us.format(1000000);
For German:
NumberFormat nf_ge = NumberFormat.getInstance(Locale.GERMAN);
String number_ge = nf_ge.format(1000000);
You can use NumberFormat.
Android documentation is quite clear on it.