Enumerations

An enumeration is a list of all the possible values in a logical collection. Java enum is a great way of, well, enumerating things. For example, if our app uses variables that can only be in a specific range of values, and if those values could logically form a collection or a set, then enumerations are probably appropriate to use. They will make your code clearer and less error-prone.

To declare an enum in Java, we use the enum keyword, followed by the name of the enumeration, followed by the values the enumeration can have, enclosed in a pair of curly braces {...}.

As an example, examine this enumeration declaration. Note that it is a convention to declare the values from the enumeration all in uppercase:

private enum zombieTypes {
    REGULAR, RUNNER, CRAWLER, SPITTER, BLOATER, SNEAKER 
};

Note at this point that we have not declared any instances of zombieTypes, just the type itself. If that sounds odd, think about it like this. We created the Apple class, but to use it,...