Modifying "msExchHideFromAddressLists" Active Directory Attribute Using JNDI

I have created an Active Directory client using JNDI, that has the ability to query for attributes, as well as modify existing ones. I have the need to modify the "msExchHideFromAddressLists" to set it equal to false, but I get a null pointer exception wh开发者_如何学JAVAen trying to query for it. Any insight? Thanks

String filter = "(&(objectCategory=user) (sAMAccountName=" + sAMAccountName + "))";
results = ctx.search(ou, filter, controls);

while(results.hasMore()) {
    SearchResult searchResult = (SearchResult) results.next();
    Attributes attributes = searchResult.getAttributes();

    Attribute attr = attributes.get("msExchHideFromAddressLists");
    String output = (String) attr.get();
}

I found out what the issue was. Apparently, the "msExchHideFromAddressLists" attribute is not valued by default, so a query on it was returning a nullPointerException. To modify this attribute, simply set the value to "TRUE" or "FALSE".

ModificationItem[] mods = new ModificationItem[1];
mods[0] = new ModificationItem(DirContext.REPLACE_ATTRIBUTE, new BasicAttribute("msExchHideFromAddressLists", "TRUE"));