Using Pattern and Matcher Classes for Regex in Java

Regular Expressions, often abbreviated as "regex," offer developers an efficient mechanism to represent string patterns, enabling complex search, replacement, and validation functions within various applications. At the heart of Java's regex capabilities lie two pivotal classes: Pattern and Matcher. The Pattern class serves as a compiled representation of a given regular expression, converting it into a format ready for matching operations. On the other hand, the Matcher class plays the role of a diligent executor, conducting pattern-matching operations on a character sequence by leveraging the pre-compiled pattern. Within the Matcher class, some of the most frequently utilized methods include matches(), which checks if the entire sequence conforms to the pattern; find(), which scouts for the pattern within the sequence; and group(), an instrumental method that fetches the portion of the text matched. Developers typically use the Pattern to transition a raw regex expression into a usable Pattern object in Java.compile() method. This method efficiently translates the regular expression into a Pattern instance, prepped for matching tasks. To illustrate this, consider an array of strings in a Java Regex example. After defining and compiling a suitable regex pattern, the array undergoes the Matcher's scrutiny to locate any matches. Such hands-on examples help realize the potential and flexibility of using regex within Java, streamlining text manipulation tasks. In this Java Regex example, we created an array of strings and ran it through a regular expression. Click Execute to run the Java Regex Example online and see the result.
Using Pattern and Matcher Classes for Regex in Java Execute
import java.util.regex.Pattern;
import java.util.regex.Matcher;

public class RegexDemo {
    public static void main(String[] args) {
        Pattern emailPattern = Pattern.compile("^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,6}$");

        String[] emails = {"[email protected]", "user@domain", "[email protected]"};

        for (String email : emails) {
            Matcher matcher = emailPattern.matcher(email);
            if (matcher.matches()) {
                System.out.println(email + " is a valid email address.");
            } else {
                System.out.println(email + " is an invalid email address.");
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