使用selenium rc和java从文本文件和sigin中读取电子邮件密码

I have a email.txt file where I am storing all email address and password written in java and by running test through selenium rc. My question is that selenium .clicks sigIn then it should go to the text file email.txt and use one of the email address and password to signIn and second time when I run the selenium tests then it should not pick up the first time the email and password it has used for signing in.I have a email.txt file where I am storing all