Get Email id using attribute ldap

package com.ldap;

import java.util.Properties;

import javax.naming.NamingEnumeration;
import javax.naming.NamingException;
import javax.naming.directory.Attributes;
import javax.naming.directory.BasicAttributes;
import javax.naming.directory.DirContext;
import javax.naming.directory.SearchControls;
import javax.naming.directory.SearchResult;
import javax.naming.ldap.InitialLdapContext;

public class GetSingleEmailIDFromLDAPUsingAttributes {

	public static void main(String[] args) {
		Properties prop = new Properties();
		prop.put("java.naming.factory.initial",
				"com.sun.jndi.ldap.LdapCtxFactory");
		prop.put("java.naming.provider.url", "ldap://domainname:portnumber");
		prop.put("java.naming.security.principal", " domainname \\username");
		prop.put("java.naming.security.credentials", "password");

		try {
			DirContext ctx = new InitialLdapContext(prop, null);
			SearchControls searchControls = new SearchControls();
			searchControls.setSearchScope(SearchControls.SUBTREE_SCOPE);
			String attlist[] = { "cn", "mail", "sn", "samaccountname" };
			String ldap_search_context = "ou=Associates,dc= domainname ,dc=companyname,dc=com";
			NamingEnumeration answer = null;
			Attributes matchAttrs = new BasicAttributes(true);
			matchAttrs.put("samaccountname", "userid");
			answer = ctx.search(ldap_search_context, matchAttrs, attlist);
			while (answer.hasMore()) {
				SearchResult sr = (SearchResult) answer.next();
				Attributes attributes = sr.getAttributes();
				System.out.println(attributes.get("mail"));

			}
			ctx.close();

		} catch (NamingException ex) {
			ex.printStackTrace();
		}
	}

}