Delete Message From A Sender In Gmail Using Java

i want to log in to my gmail account, filter spam and delete them.But i want to delete only spam from a particular sender,How can i delete all messages from this sender only?The code i found is here but it.s not deleting any messages:

Java Code: import java.util.Properties;
import javax.mail.Address;

import javax.mail.Flags;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.NoSuchProviderException;
import javax.mail.Session;
import javax.mail.Store;

[code]....