The full enum syntax actually provides quite a bit more power and flexibility:
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You can define your own fields, methods, and constructors for the enumerated type.
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If you define one or more constructors, you can invoke a constructor for each enumerated value by following the value name with constructor arguments in parentheses.
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Although an enum may not extend anything, it may implement one or more interfaces.
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Most esoterically, individual enumerated values can have their own class bodies that override methods defined by the type.
Rather than formally specifying the syntax for each of these advanced enum declarations, we'll demonstrate the syntax in the examples that follow.
for example:
public enum Prefix {
// These are the values of this enumerated type.
// Each one is followed by constructor arguments in parentheses.
// The values are separated from each other by commas, and the
// list of values is terminated with a semicolon to separate it from
// the class body that follows.
MILLI("m", .001),
CENTI("c", .01),
DECI("d", .1),
DECA("D", 10.0),
HECTA("h", 100.0),
KILO("k", 1000.0); // Note semicolon
// This is the constructor invoked for each value above.
Prefix(String abbrev, double multiplier) {
this.abbrev = abbrev;
this.multiplier = multiplier;
}
// These are the private fields set by the constructor
private String abbrev;
private double multiplier;
// These are accessor methods for the fields. They are instance methods
// of each value of the enumerated type.
public String abbrev() { return abbrev; }
public double multiplier() { return multiplier; }
}