A possible solution would be to strip the accent with the help of Apache Commons StringUtils.stripAccents(input) method:

String input = StringUtils.stripAccents("János");
System.out.println(input); //Janos

Make sure to also read upon the more elaborate approaches based on the Normalizer class: Is there a way to get rid of accents and convert a whole string to regular letters?

Hi I think that this answers your question :) just add another forbidden character to set and it will simply filter that char too.

   Set<Character> forbiddenChars = Set.of('s', '{', '}', ' ');

        String testString = "This Is{ Test} string";

        String filteredString = testString
                                        .toLowerCase()
                                        .codePoints()
                                        .filter(character -> !forbiddenChars.contains((char)character))
                                        .collect(StringBuilder::new, StringBuilder::appendCodePoint,
                                                    StringBuilder::append)
                                        .toString();
        System.out.println(filteredString);

Added the below line and should work

String str = s1.replaceAll("[,']"," ");

Best way to test your regex are http://regexr.com/

Java: str.toLowercase().replace("[^a-zA-Z]", "") will render them all in lowercase with special chars removed and therefore all equal()

Edited to cover everything not alpha as "special"

Most probably getting the Edit Distance/ Levenshtein distance should resolve your issue. This is not an ideal solution but you may use it with significant success.

Check it Your Self

Levenshtein Distance in Java

I think replacing all spaces with an empty string poses the danger of verifying the following situation (finding the two names equal):

String a = "ANN MARIE O'RIORDAN"
String b = "ANNMARIE O'RIORDAN"

I know I may be splitting hairs here, but I found this question while looking for a similar solution to verify SQL queries in a unit test. Because my queries are multi-line static final Strings, I wanted to make sure that I didn't miss a space anywhere.

To that end, I think replacing all whitespaces with a single space, or perhaps a special character is the safest solution - which then does require regex:

if (a.trim().replaceAll("\\s+", " ").equalsIgnoreCase(b.trim().replaceAll("\\s+", " "))) {
    // Strings equivalent
}

Thoughts?