How can I validate user input in Java?

How can I validate user input in Java?

You can validate user input in Java using various methods like regular expressions, if statements, or validation frameworks.

Can you give me an example using regular expressions?

Sure! You can use the Pattern and Matcher classes to validate an email address. Here's a simple example:

import java.util.regex.*;

public class EmailValidator {
    public static void main(String[] args) {
        String email = "[email protected]";
        String regex = "^[A-Za-z0-9+_.-]+@[A-Za-z0-9.-]+$";
        Pattern pattern = Pattern.compile(regex);
        Matcher matcher = pattern.matcher(email);
        System.out.println(matcher.matches() ? "Valid email" : "Invalid email");
    }
}

What if I want to validate a phone number instead?

You can use a similar approach. Here's an example for validating a phone number:

String phoneNumber = "123-456-7890";
String regex = "^\d{3}-\d{3}-\d{4}$";
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(phoneNumber);
System.out.println(matcher.matches() ? "Valid phone number" : "Invalid phone number");