Question

Regexp in Java
I want to make a regexp who do this
verify if a word is like [0-9A-Za-z][._-‘][0-9A-Za-z]
example for valid words

A21a_c32 
daA.da2
das'2
dsada
ASDA
12SA89

non valid words

dsa#da2
34$

Thanks

Answer 1

^[0-9A-Za-z]+[._'-]?[0-9A-Za-z]+$ (see matches on rubular.com)

Key points:

• ^ is the start of the string anchor
• $ is the end of string anchor
• + is “one-or-more repetition of”
• ? is “zero-or-one repetition of” (i.e. “optional”)
• - in a character class definition is special (range definition)…
  • unless it’s escaped, or first, or last
• . unescaped outside of a character class definition is special…
  • but in a character class definition it’s just a period

References

• regular-expressions.info/Anchors, Repetition, Dot, Character Class