diff --git a/client/src/pages/guide/english/java/regular-expressions/index.md b/client/src/pages/guide/english/java/regular-expressions/index.md index 2d02139213..4566cf6743 100644 --- a/client/src/pages/guide/english/java/regular-expressions/index.md +++ b/client/src/pages/guide/english/java/regular-expressions/index.md @@ -1,13 +1,53 @@ --- title: Regular Expressions --- -## Regular Expressions +# Regular Expressions -This is a stub. Help our community expand it. +### Introduction +Regular expressions in Java are useful for searching, editing and manipulating strings. Regular Expressions are also known as Regex. -This quick style guide will help ensure your pull request gets accepted. +### Java Regex provides three classes in java.util.regex package: +- Matcher +-- Used for defining the String pattern to match +- Pattern +-- Used for peforning math on given pattern +- PatternSyntaxException +-- Used for indicate exceptions in the pattern + +### RegEx Example: +- Check that the string contains only characters and no numbers or special characters. +``` +import java.util.regex.*; + +public class RegExExample { + public static final String ARTICLE_STRING = "freecodecamp"; + + public static void main(String[] args) { + Pattern pattern = Pattern.compile("^[a-zA-Z]*$"); + Matcher match = pattern.matcher(ARTICLE_STRING); + boolean result = match.matches(); + System.out.println("Result: " + result); + } +} +``` + +``` +Result: true +``` + +### Understanding the pattern: +```"^[a-zA-Z]*$"``` + +^ - The beginning of a line +[a-zA-Z] - Match characters from a-z and A-Z +*$ - The end of the line + +### RegEx Cheatsheet: +- Here is a very good link to [RegEx Cheatsheet](https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html) - #### More Information: +- [Class Pattern](https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html) +- [Lesson on Regular Expression](https://docs.oracle.com/javase/tutorial/essential/regex/) +