RegEx

import java.util.Scanner;

public class reg {

    public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);

    String text = "Email:[email protected], [email protected]";
    String censored = text.replaceAll("[A-Za-z_-]+@[A-za-z]+\\.[a-zA-Z]+","*****@abv.bg");
    System.out.println(censored);

    }

}