? Java Pattern & Matcher

? Quick Overview

The Pattern and Matcher classes in Advance Java are part of java.util.regex. They provide powerful regular expression support for searching, matching, and extracting text patterns.

? Key Concepts

• Pattern – Compiled representation of a regular expression
• Matcher – Engine that performs match operations
• find() – Searches for next matching subsequence
• matches() – Matches entire input sequence
• group() – Extracts matched text

? Syntax & Theory

In Java, regular expressions are first compiled using the Pattern class. The compiled pattern is then used by a Matcher to perform operations on character sequences.

// Import regex package
import java.util.regex.*;

public class PatternDemo {
public static void main(String[] args) {

// Compile a regular expression
Pattern pattern = Pattern.compile("java");

// Input text where pattern will be searched
Matcher matcher = pattern.matcher("I love java programming");

// Check if pattern exists
while (matcher.find()) {
System.out.println("Match found at index: " + matcher.start());
}
}
}

? Live Output / Explanation