Check if string is a punctuation character

Question

Let\'s say I have a String array that contains some letters and punctuation

String letter[] = {\"a\",\"b\",\"c\",\".\",\"a\"};

In letter[3]

Answer 1

Depending on your needs, you could use either

Pattern.matches("\\p{Punct}", str)

or

Pattern.matches("\\p{IsPunctuation}", str)

The first pattern matches the following 32 characters: !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~

The second pattern matches a whopping 632 unicode characters, including, for example: «, », ¿, ¡, §, ¶, ‘, ’, “, ”, and ‽.

Interestingly, not all of the 32 characters matched by the first pattern are matched by the second. The second pattern does not match the following 9 characters: $, +, <, =, >, ^, `, |, and ~ (which the first pattern does match).

If you want to match for any character from either character set, you could do:

Pattern.matches("[\\p{Punct}\\p{IsPunctuation}]", str)