A **regular expression**​ is a defined pattern used for matching and manipulating strings. In Java, there is a built-in API for regular expressions:
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```Java
java.util.regex package
```
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This package has three classes:
1. [Pattern class](https://www.educative.io/shoteditor/6600010382704640/preview)
2. Matcher class
3. [PatternSyntaxException class](https://www.educative.io/shoteditor/5588895892766720/preview)
>This regular expression is not the property of one particular programming language; instead, it is supported by multiple languages.

# Matcher class
The **`util.regex.Matcher`** is used for match operations using the text patterns.
Some of the most commonly used methods are:

| **Methods**    | **Description**    |
| --- | --- |
| `find()`     | It searches the occurrences of an expression in a text.    |
|  `find(int index)`   | It searches the occurrences of an expression in a text from the given index.    |
|  `start()`   |  It returns the starting index of the match that is found.    |
| `end()`    | It returns the ending index of the match that is found.    |
| `groupCount()`    |  It returns an integer value for the total number of matched values.    |



// Java program 
import java.util.regex.Matcher; 
import java.util.regex.Pattern; 

class Main 
{ 
	public static void main(String [] arguments) 
	{ 
		// Create a pattern to be searched 
		Pattern pttrn = Pattern.compile("Ah*"); 

		// Search the pattern in the given text
		Matcher mtch = pttrn.matcher("Ahhhhh! I lost my job."); 

		// search and print the starting and ending index using
    // end() and start() function.
		while (mtch.find()) 
			System.out.println("Starting index: " + mtch.start() + 
							" Ending index: " + (mtch.end()-1)); 
	} 
} 


In the above code, some of the functions from the pattern class are used. These are detailed [here](https://www.educative.io/shoteditor/6600010382704640/preview).

> The **"\*"** symbol in the above code means that the character before it can repeat finitely at that position (e.g., hel*o is equivalent to hello). 

What is a regex.Matcher class in Java?

A regular expression​ is a defined pattern used for matching and manipulating strings. In Java, there is a built-in API for regular expressions:  java.util.regex package   This package has three classes:  Pattern class Matcher class PatternSyntaxException class   This regular expression is not the property of one particular programming language; instead, it is supported by multiple languages.  

Methods	Description
`find()`	It searches the occurrences of an expression in a text.
`find(int index)`	It searches the occurrences of an expression in a text from the given index.
`start()`	It returns the starting index of the match that is found.
`end()`	It returns the ending index of the match that is found.
`groupCount()`	It returns an integer value for the total number of matched values.

What is a regex.Matcher class in Java?

Matcher class

Code