Java Regex Finder Example

Sure, here is a simple example of using Java Regex (Regular Expressions) to find a pattern in a string:

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
    public static void main(String[] args) {
        // Input string to be searched
        String text = "This is a sample text that contains [email protected]";

        // Define regex pattern
        String patternString = "[a-zA-Z0-9._%-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,4}";

        // Compile regex pattern
        Pattern pattern = Pattern.compile(patternString);

        // Create matcher object
        Matcher matcher = pattern.matcher(text);

        // Find matches
        while (matcher.find()) {
            // Print the matched text and its starting position
            System.out.println("Found match: " + matcher.group() + " at position " + matcher.start());
        }
    }
}

In this example, we are searching for an email address in the input string. The regex pattern [a-zA-Z0-9._%-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,4} is used to match any email address. The Pattern.compile() method is used to compile the regular expression into a Pattern object. The matcher() method is then used to create a Matcher object from the Pattern object. The find() method of the Matcher object is used in a loop to find all matches in the input string. For each match, we print the matched text and its starting position in the input string.