How to remove high-ASCII characters from string like ®, ©, ™ in Java

Question

I want to detect and remove high-ASCII characters like ®, ©, ™ from a String in Java. Is there any open-source library that can do this?

Answer 1

If you need to remove all non-US-ASCII (i.e. outside 0x0-0x7F) characters, you can do something like this:

s = s.replaceAll("[^\\x00-\\x7f]", "");

If you need to filter many strings, it would be better to use a precompiled pattern:

private static final Pattern nonASCII = Pattern.compile("[^\\x00-\\x7f]");
...
s = nonASCII.matcher(s).replaceAll();

And if it's really performance-critical, perhaps Alex Nikolaenkov's suggestion would be better.

Answer 2

I think that you can easily filter your string by hand and check code of the particular character. If it fits your requirements then add it to a StringBuilder and do toString() to it in the end.

public static String filter(String str) {
    StringBuilder filtered = new StringBuilder(str.length());
    for (int i = 0; i < str.length(); i++) {
        char current = str.charAt(i);
        if (current >= 0x20 && current <= 0x7e) {
            filtered.append(current);
        }
    }

    return filtered.toString();
}

Answer 3

I understand that you need to delete: ç,ã,Ã , but for everybody that need to convert ç,ã,Ã ---> c,a,A please have a look at this piece of code:

Example Code:

final String input = "Tĥïŝ ĩš â fůňķŷ Šťŕĭńġ";
System.out.println(
    Normalizer
        .normalize(input, Normalizer.Form.NFD)
        .replaceAll("[^\\p{ASCII}]", "")
);

Output:

This is a funky String

Answer 4

A nice way to do this is to use Google Guava CharMatcher:

String newString = CharMatcher.ASCII.retainFrom(string);

newString will contain only the ASCII characters (code point < 128) from the original string.

This reads more naturally than a regular expression. Regular expressions can take more effort to understand for subsequent readers of your code.