Java - Regular Expressions Part 3: Pattern and Matcher Classes

Example 1: Finding All Matches

Pattern pattern = Pattern.compile("\\d+");

Matcher matcher = pattern.matcher("Order123, Item456");

while (matcher.find()) {

    System.out.println("Match: " + matcher.group());

}

// Match: 123

// Match: 456

Example 2: Using group()

Pattern pattern = Pattern.compile("(\\w+)@(\\w+\\.com)");

Matcher matcher = pattern.matcher("[email protected]");

if (matcher.find()) {

    System.out.println("User: " + matcher.group(1));    // User: user

    System.out.println("Domain: " + matcher.group(2)); // Domain: example.com

}

Example 3: Start and End Index

Pattern pattern = Pattern.compile("\\d+");

Matcher matcher = pattern.matcher("Price is 300 dollars");

if (matcher.find()) {

    System.out.println("Start: " + matcher.start() + ", End: " + matcher.end());

}

// Start: 9, End: 12

Example 4: Checking Entire Match

Pattern pattern = Pattern.compile("\\d+");

Matcher matcher = pattern.matcher("12345");

System.out.println("Entire match: " + matcher.matches()); // true