import java.util.Scanner;

public class Main {

public static void main(String[] args) {

    Scanner scanner = new Scanner(System.in);
    String str = scanner.next();
    String emailMatcher="[a-zA-Z0-9]+@[a-zA-Z0-9]+\\.[a-zA-Z0-9]+";

    //write your code here......
    
    if(str.matches(emailMatcher)){
        System.out.println("邮箱格式合法");
    }else{
        System.out.println("邮箱格式不合法");
    }
}

}

用matches来比较正则表达式里的内容