How to get the MutableAuthenticationService ?

[hatspeed]

hi everyone , i need help

i don't now how to get the MutableAuthenticationService , i want to disable a user account
i have used this code , it doesn't work


MutableAuthenticationService authenticationService=new MutableAuthenticationServiceImpl();
   authenticationService.authenticate("admin", "admin".toCharArray());
   authenticationService.setAuthenticationEnabled("user1", false);




java.lang.NullPointerException


plzzz help


Hatspeed

[hatspeed]

nobody can help .
i am still waiting