Java file handling – io. User login and registration, with password. Using text file

I’m looking to create a class system enabling registration of a new user and login with a password. I have text file which has information about users(each registered user has to be assigned an userID then this has to be stored in a new file?):

userId,movieId,rating,timestamp

1,2294,2.0,1260759108
1,2455,2.5,1260759113
1,2968,1.0,1260759200
2,3671,3.0,1260759117
2,10,4.0,835355493
3,17,5.0,835355681
...
671,6565,3.5,1074784724

So the user should have features such as user ID, name, age, gender, password, etc. I’m looking to store this user information in a binary file.Taking into consideration of java file handing and exceptions, how about should I go about doing this?

Im thinking of having a user class and a tester class as later I will be using GUI.