Or if this is a real-life question and not just a beginner's programming exercise, you could replace the whole thing by calls to various methods in the TimeZone class. No "ifs" would be required there.
Sounds like the perfect fit for the Strategy Design Pattern. Some proponents of language theory proclaim that a single if/else is a broken construct and does not belong in a complete language. While I haven't bought that argument just yet, I certainly agree with the more wider (though still small relative to the critical mass) understanding that a if/else/else (3 or more statement bodies) should always be avoided. I even know a few who claim that for loops are flawed constructs!! I haven't bought that argument, simply because I don't understand it in completeness yet, but I suspect that they are ultimately right. For the same reason - appropriate abstraction/accurate requirement expression - switch/case constructs should always be avoided.
The point being, I suspect that your teacher (a knowledagable academic?) is probably trying to teach you something related to this and I encourage you to pursue it further.
The Strategy Design Pattern - one of few legitimate design patterns - is implemented in Java almost always using a java.util.Map. If you wish to go for further purity (but falling infinitely short implied by Java), you might want to consider net.tmorris.adt.map.Map - or just write the interface yourself. Minimalism is paramount even though it is often unachievable under a given context. So often I observe suffering as a result of excessive expression of requirement/contract, and worse, I observe the resulting "problem" attributed to a consequence, instead of the underlying flaws.
Good to hear of a tertiary institution on the right path ...if indeed that is what is happening.