Regex scenarios to Match Strings with Mixed Case in Java - Need guide with Case Sensitivity
I've been researching this but After trying multiple solutions online, I still can't figure this out. I'm currently working on a Java application where I need to validate user input against a regex pattern that should match a specific format. The input strings are expected to be in the format of 'Item123', where 'Item' can start with either uppercase or lowercase letters, and the number can be any digits following it. I initially wrote a regex pattern like this: `^[A-Za-z]+\d+$`. However, I've run into issues where mixed-case strings like 'item123' or 'ITEM123' unexpected result to match, which is unexpected because I believed my character class should accommodate both cases. Here’s the code snippet I’m using: ```java import java.util.regex.*; public class RegexTest { public static void main(String[] args) { String input = "item123"; // Change this to test different cases String pattern = "^[A-Za-z]+\d+$"; Pattern compiledPattern = Pattern.compile(pattern); Matcher matcher = compiledPattern.matcher(input); if (matcher.matches()) { System.out.println("Input matches the pattern."); } else { System.out.println("Input does NOT match the pattern."); } } } ``` I've already tried changing the regex to `(?i)^[A-Za-z]+\d+$`, which should make it case-insensitive, but it leads to a compilation behavior stating "unrecognized group". I'm on Java 11, and I'd like some guidance on how to correctly implement case insensitivity in this regex. Any insights into what I might be doing wrong would be greatly appreciated! My development environment is Ubuntu. Is there a better approach?