import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
public static void main(String[] argv) throws Exception {
// Use COMMENTS but include a character class with a space
CharSequence inputStr = "a b";
String patternStr = "a b";
// Compile without comments
Pattern pattern = Pattern.compile(patternStr);
Matcher matcher = pattern.matcher(inputStr);
boolean matchFound = matcher.matches();
// Compile with comments
pattern = Pattern.compile(patternStr, Pattern.COMMENTS);
matcher = pattern.matcher(inputStr);
matchFound = matcher.matches();
patternStr = "a [\\ ] b";
pattern = Pattern.compile(patternStr, Pattern.COMMENTS);
matcher = pattern.matcher(inputStr);
matchFound = matcher.matches();
}
}