Encrytping SharedPreferences login credentials

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I am a novice at android app dev. I have a login screen aplication that is saving my SharedPreferences username and password in cleartext. I want to use MAPL to encrypt this data. Is that possible?  I have followed the "How to Sharedpreferences" instructions and when my application is launched in eclipse I get prompted to create pin. once pin is setup my registration and login activity do not start...please advise