How to check if a String is numeric in Java

Question

How would you check if a String was a number before parsing it?

Answer 1

Java 8 Stream, lambda expression, functional interface

All cases handled (string null, string empty etc)

String someString = null; // something="", something="123abc", something="123123"

boolean isNumeric = Stream.of(someString)
            .filter(s -> s != null && !s.isEmpty())
            .filter(Pattern.compile("\\D").asPredicate().negate())
            .mapToLong(Long::valueOf)
            .boxed()
            .findAny()
            .isPresent();