Get All Email Id from LDAP

package com.ldap;

import java.util.Properties;

import javax.naming.Context;
import javax.naming.NamingEnumeration;
import javax.naming.NamingException;
import javax.naming.directory.Attribute;
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 GetAllEmailIDFromLDAP {
	public GetAllEmailIDFromLDAP()  
	   {  
	     Properties prop = new Properties();  
	     prop.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");  
	     prop.put(Context.PROVIDER_URL, "ldap://domainname:portnumber");  
	     prop.put(Context.SECURITY_PRINCIPAL, " domainname\\username");  
	     prop.put(Context.SECURITY_CREDENTIALS, "password");

	     try {  

	       DirContext ctx = new InitialLdapContext(prop, null);              
	       SearchControls searchControls=new SearchControls();
	       searchControls.setSearchScope(SearchControls.SUBTREE_SCOPE);
	       String ldap_search_context ="ou=Associates,dc= domainname,dc=companyname,dc=com";
	       NamingEnumeration answer = null;
	       Attributes matchAttrs = new BasicAttributes(true);
	       matchAttrs.put("samaccountname","mail");
	       String lettersValue="a;b;c;d;e;f;g;h;i;j;k;l;m;n;o;p;q;r;s;t;u;v;w;x;y;z;";
	       String letters[]=lettersValue.split(";");
	       int i=0;
	       for (String string : letters) {
	        answer = ctx.search(ldap_search_context, "mail="+string+"*",searchControls);
	       while(answer.hasMore())
	       {
	        SearchResult sr = (SearchResult)answer.next();
	        Attributes attributes=sr.getAttributes();
	        Attribute mailID=attributes.get("mail");
	        if (mailID!=null) {
	        System.out.println("Total No: "+i+"  "+mailID.get());
	   }
	        i++;

	       }  
	   }

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

	   }  

	   public static void main(String[] args)  
	   {  
	   GetAllEmailIDFromLDAP ldaptest = new GetAllEmailIDFromLDAP();  
	   } 
}