hi . . .
don't worry if you don't have any java back ground, just prepare in a correct manner, as you have 10 days left you can still improve your skills, first of all do some coding (from Book), it will give you confidence. There are many online Test
resources, you can give those online test . . and don't forget to revise all the topics in last 2 days . . . Generics and Multithreading are very important topics . . give more attention to that . . . .
best of luck for the exam . . . believe in yourself and concentrate on your strengths!!