Putting this up for
my own reference more than any other reason. Java Regex are useful in
manipulation strings. A regex consist of pattern blocks and optional
quantifiers.
Pattern Blocks
some patterns are built in to java,
\d - digit
\w – word character
\s – whitespace
if a range of characters need to be used as a pattern it should be
put as follows,
[a-z] – a to z simple
[a-zA-Z] - a to z capital and simple
[1-9] – 1 to 9
Quantifiers
these add meaning to the patterns. They should be added immediately
after the pattern.
* - match pattern 0 or more times
+ - match pattern 1 or more times
{n} - match pattern exactly n times
{n,m} – match pattern between n to m times
Regex Examples
[a-zA-Z]* - a to z capital and simple 0 or more times
[a-zA-Z]+ - a to z capital and simple 1 or more times
\d{2,5} – digits 2 to 5 times
[.]*[a-zA-Z]{1,5} - . 0 or more times in the beginning followed by a
to z capital and simple 1 to 5 time, the whole pattern once.
