import java.util.regex.Pattern;

public class Main {
    public static void main(String[] args) {
        // there is the variant selector (U+FE0F) after the heart emoji
        String strWithVariantSelector = "❤️ file.txt";

        String expr = "^[^/]*\\.[^/]*$";
        Pattern pattern = Pattern.compile(expr);
        Pattern patternWithCanonEq = Pattern.compile(expr, Pattern.CANON_EQ);

        boolean patternMatches = pattern.matcher(strWithVariantSelector).matches();
        boolean patternWithCannonMatches = patternWithCanonEq.matcher(strWithVariantSelector).matches();

        System.out.println(patternMatches); //true
        System.out.println(patternWithCannonMatches); //false
    }
}