Character.getNumericValue has unexpected behaviour: it interprets A-Z as base-36 digits with values 10-35, but also supports non-arabic numerals and miscellaneous numeric unicode characters like ㊷. For example:

• Character.getNumericValue('V' /* ASCII V */) == 31
• Character.getNumericValue('Ⅴ' /* U+2164, Roman numeral 5 */) == 5
• Character.getNumericValue('௧' /* U+0BF2, Tamil Digit One */) == 1
• Character.getNumericValue('௲' /* U+0BF2, Tamil Number One Thousand */) == 1000
• Character.getNumericValue('㊷' /* U+32B7, Circled Number Forty Two */) == 42

UCharacter.getNumericValue has the same behavior.

Consider using:

• UCharacter.getUnicodeNumericValue: Handles all unicode codepoints with numeric values including fractions, roman numerals, and other miscellaneous numeric characters. Returns the value as a double. Does not assign a value to A-Z.
• Character.digit: Handles unicode codepoints in the “decimal digit” category and the letters A-Z which are interpreted as base-36 digits with values 10-35. Does not handle characters like roman numerals and ㊷. You can use a radix value of 10 or less to avoid interpreting A-Z as digits.