Replaces the first substring of this string that matches the given regular expression with the given replacement.
An invocation of this method of the form str.replaceFirst(regex, repl) yields exactly the same result as the expression
Note that backslashes (\) and dollar signs ($) in the
replacement string may cause the results to be different than if it were
being treated as a literal replacement string; see
java.util.regex.Matcher.quoteReplacement to suppress the special
meaning of these characters, if desired.
|the regular expression to which this string is to be matched|
|the string to be substituted for the first match|
|if the regular expression's syntax is invalid|