You should not use == to compare strings. Use .equals(...) instead.
The == operator compares object references. The result of comparing two references will only be true when the two references on the left and right side of the == refer to the exact same object. If you have two String objects with the same content, then the result will be false, because you have to distinct String objects.
So, you'll need to use:
Note that you will probably have to add null checks as well, because if 'choice' is 'null' you will get a NullPointerException if you try to call a method such as equals on it.