According to Apache Commons Lang's documentation for StringUtils.isNumeric(), the String '???' is numeric.
Since I believed this might be a mistake in the documentation, I ran tests to verify the statement. I found that according to Apache Commons it is numeric.
Why is this String numeric? What do those characters represent?
See Question&Answers more detail:os
Because that "CharSequence contains only Unicode digits" (quoting your linked documentation).
All of the characters return true for Character.isDigit:
Some Unicode character ranges that contain digits:
- 'u0030' through 'u0039', ISO-LATIN-1 digits ('0' through '9')
- 'u0660' through 'u0669', Arabic-Indic digits
- 'u06F0' through 'u06F9', Extended Arabic-Indic digits
- 'u0966' through 'u096F', Devanagari digits
- 'uFF10' through 'uFF19', Fullwidth digits
Many other character ranges contain digits as well.
??? are Devanagari digits:
