java - Check that String is alphanumeric with length 1 to 5

Question

I have wrote the following test code snippet:

"123".matches("\[a-zA-Z0-9]{1,5}");

However, it returns false.

Why and how to fix this?

question from:https://stackoverflow.com/questions/65938869/how-to-in-kotlin-match-english-letters-in-mixed-string

Answer 1

You're escaping the first square bracket with the \, which means the expression between the square brackets isn't treated as a character class. Remove the escaping and you should be OK:

"123".matches("[a-zA-Z0-9]{1,5}"
// Here -------^