正则表达式查找不区分大小写的用户名

Question

I am trying to create a method to check for unique usernames. For example, if the username JOHN exists, someone else shouldn't pick the username John . My only problem is that I can't find the good regex for it. I tried the following:

ParseQuery query = ParseUser.getQuery();
String regex = nickname.getText().toString().toLowerCase();
query.whereMatches("username", regex, "i");

But this also gives the users who have the username Johnny . How can I only find the username John case insensitive?

Answer 1

Replacing "username" with "^username$" should ensure that the entire string matches. Since you are passing the i flag, it should match without taking into consideration the difference in casing.

That being said, I am not 100% sure if regular expressions are the answer, since all you need to do is case insensitive comparisons, which should be handled by some string function.