java正则表达式判断邮件地址是否合法

import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.Scanner;
public class Email{
    public static void main(String []args){
        Scanner scan = new Scanner(System.in);
        String str=null;
        str = scan.next();
        String pat="[a-zA-Z0-9_\-\.]+@[a-zA-Z0-9]+(\.(com))";
        Pattern p = Pattern.compile(pat);//实例化Pattern类
        Matcher m = p.matcher(str);//验证内容是否合法
        if(m.matches())
          System.out.println("YES");
        else
          System.out.println("NO");
    }
}</pre>