unicode as part of string

Good evening.

While looking at a String, i would like to somehow guarantee that is does or does not contain a unicode character. Does Java let us natively solve this task?

Please let me know how

thanks

PS: Let me add 1 item of clarification. Assume, i am literally looking at "Hello\u1001world" String. Say, if i pass it to a method that will break it down char by char and will test if its decimal value is < 128 .. well that won't work, since split will take \ and u and 1 and 1 etc literally. I support i can use if String.matches("blah"), but wonder if there is a more elegant way to do it