如何检查一个字符串上多少个非字母数字字符

Question

i'm trying to check how many non-alphanumeric characters can be found on a string for example:

String message = "i'm a keyboard!!!"

i want to check how many "!" and " ' " can be found on that string, not only those, but any symbol.

Answer 1

Regular expressions would be good for this. Try just replacing alphanumeric character with nothing and taking the length.

pattern = "[a-zA-Z0-9]*"
newString = message.replaceAll(pattern, "")
return newString.length