CODEWITHSUNDEEP
javaregex
Marco Lau
Marco Lau

Reputation: 619

Regex of base classes

I am trying to create a hexadecimal calculator but I have a problem with the regex.

Basically, I want the string to only accept 0-9, A-E, and special characters +-*_

My code keeps returning false no matter how I change the regex, and the adding the asterisk is giving me a PatternSyntaxException error.

public static void main(String[] args) {

    String input = "1A_16+2B_16-3C_16*4D_16";

    String regex = "[0-9A-E+-_]";

    System.out.println(input.matches(regex));

}

Also whenever I add the * as part of the regex it gives me this error:

Exception in thread "main" java.util.regex.PatternSyntaxException: Illegal character range near index 9
[0-9A-E+-*_]+
         ^

Upvotes: 0

Views: 340

Answers (3)

André Vitor
André Vitor

Reputation: 59

public static boolean isValidCode (String code) {
    Pattern p = Pattern.compile("[fFtTvV\\-~^<>()]+"); //a-zA-Z
    Matcher m = p.matcher(code);
    return m.matches();
}

Upvotes: 0

FDinoff
FDinoff

Reputation: 31439

You need to match more than one character with your regex. As it currently stands you only match one character.

To match one or more characters add a + to the end of the regex

[0-9A-E+-_]+

Also to match a * just add a star in the brackets so the final regex would be 

[0-9A-E+\\-_*]+

You need to escape the - otherwise the regex thinks you want to accept all character between + and _ which is not what you want.

Upvotes: 3

Evgeniy Dorofeev
Evgeniy Dorofeev

Reputation: 136062

You regex is OK there should be no exceptions, just add + at the end of regex which means one or more characters like those in brackets, and it seems you wanted * as well

"[0-9A-E+-_]+"

Upvotes: 1

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