With this, we come to an end of Java String Cheat Sheet. Check out the Java Training by Edureka, a trusted online learning company with a network of more than 250,000 satisfied learners spread across the globe. Edureka’s Java, J2EE & SOA Certification Training is designed for students and professionals who want to be a Java Developer. Regular expression syntax cheatsheet This page provides an overall cheat sheet of all the capabilities of RegExp syntax by aggregating the content of the articles in the RegExp guide. If you need more information on a specific topic, please follow the link on the corresponding heading to access the full article or head to the guide. Regular Expressions Cheat Sheet for Python, PHP, Perl, JavaScript and Ruby developers. The list of the most important metacharacters you'll ever need. Groovy’s basic types; Type Literals Notes; java.lang.String 'hi', 'hi', /hi/, $/hi/$ Double quotes allow embedded expressions. Slashes mean you don’t need to escape characters, the dollar slashes mean you don’t need to escape / characters (good for regular expressions).

The Java Regex or Regular Expression is an API to define a pattern for searching or manipulating strings.

It is widely used to define the constraint on strings such as password and email validation. After learning Java regex tutorial, you will be able to test your regular expressions by the Java Regex Tester Tool.

Java Regex API provides 1 interface and 3 classes in java.util.regex package.

java.util.regex package

The Matcher and Pattern classes provide the facility of Java regular expression. The java.util.regex package provides following classes and interfaces for regular expressions.

  1. MatchResult interface
  2. Matcher class
  3. Pattern class
  4. PatternSyntaxException class

Matcher class

It implements the MatchResult interface. It is a regex engine which is used to perform match operations on a character sequence.

No.MethodDescription
1boolean matches()test whether the regular expression matches the pattern.
2boolean find()finds the next expression that matches the pattern.
3boolean find(int start)finds the next expression that matches the pattern from the given start number.
4String group()returns the matched subsequence.
5int start()returns the starting index of the matched subsequence.
6int end()returns the ending index of the matched subsequence.
7int groupCount()returns the total number of the matched subsequence.

Pattern class

It is the compiled version of a regular expression. It is used to define a pattern for the regex engine.

No.MethodDescription
1static Pattern compile(String regex)compiles the given regex and returns the instance of the Pattern.
2Matcher matcher(CharSequence input)creates a matcher that matches the given input with the pattern.
3static boolean matches(String regex, CharSequence input)It works as the combination of compile and matcher methods. It compiles the regular expression and matches the given input with the pattern.
4String[] split(CharSequence input)splits the given input string around matches of given pattern.
5String pattern()returns the regex pattern.

Java Regex Cheat Sheet Pdf

Example of Java Regular Expressions

There are three ways to write the regex example in Java.

Java Design Pattern Cheat Sheet

Test it Now

Output

Sheet

Regular Expression . Example

The . (dot) represents a single character.

Test it Now

Regex Character classes

No.Character ClassDescription
1[abc]a, b, or c (simple class)
2[^abc]Any character except a, b, or c (negation)
3[a-zA-Z]a through z or A through Z, inclusive (range)
4[a-d[m-p]]a through d, or m through p: [a-dm-p] (union)
5[a-z&&[def]]d, e, or f (intersection)
6[a-z&&[^bc]]a through z, except for b and c: [ad-z] (subtraction)
7[a-z&&[^m-p]]a through z, and not m through p: [a-lq-z](subtraction)

Regular Expression Character classes Example

Test it Now

Regex Quantifiers

The quantifiers specify the number of occurrences of a character.

RegexDescription
X?X occurs once or not at all
X+X occurs once or more times
X*X occurs zero or more times
X{n}X occurs n times only
X{n,}X occurs n or more times
X{y,z}X occurs at least y times but less than z times

Regular Expression Character classes and Quantifiers Example

Test it Now

Regex Metacharacters

The regular expression metacharacters work as shortcodes.

RegexDescription
.Any character (may or may not match terminator)
dAny digits, short of [0-9]
DAny non-digit, short for [^0-9]
sAny whitespace character, short for [tnx0Bfr]
SAny non-whitespace character, short for [^s]
wAny word character, short for [a-zA-Z_0-9]
WAny non-word character, short for [^w]
bA word boundary
BA non word boundary

Regular Expression Metacharacters Example

Test it Now

Regular Expression Question 1

Test it Now

Regular Expression Question 2

Test it NowRegular expression cheat sheet

Java Regex Finder Example

Output:

Next TopicJava Exception Handling