what is regex and where i can learn

Question

what is regex and where i can learn it for java

Answer 1

regexr.com

Answer 2

Definition:
https://en.m.wikipedia.org/wiki/Regular_expression
I'm sure you can find tutorials on the internet very easy.
To use regex in Java you can use the Pattern class, see
https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html

Answer 3

A regular expression, regex or regexp (sometimes called a rational expression) is, in theoretical computer science and formal language theory, a sequence of characters that define a search pattern. Usually this pattern is then used by string searching algorithms for "find" or "find and replace" operations on strings.

http://www.vogella.com/tutorials/JavaRegularExpressions/article.html

Answer 4

You can also practice and check your regex patterns here: www.regex101.com
At least for Python, JavaScript, PHP and GoLang.

Answer 5

thanku friends

Answer 6

Also the Python tutorial of Solo Learn has a very good section about Regular Expressions (beginner level but clear and useful!)