Checks whether the String a valid Java number.
Checks whether the String a valid Java number.
Valid numbers include hexadecimal marked with the 0x or
0X qualifier, octal numbers, scientific notation and numbers
marked with a type qualifier (e.g. 123L).
Non-hexadecimal strings beginning with a leading zero are
treated as octal values. Thus the string 09 will return
false, since 9 is not a valid octal value.
However, numbers beginning with 0. are treated as decimal.
Null and empty String will return
false.
the String to check
true if the string is a correctly formatted number
3.3 the code supports hex { @code 0Xhhh} and octal { @code 0ddd} validation