If you only want to create relationships between enum values, you can actually use the trick of using other enum values:
public enum Person {
GRANDPARENT(null),
PARENT(GRANDPARENT),
CHILD(PARENT);
private final Person parent;
private Person(Person parent) {
this.parent = parent;
}
public final Parent getParent() {
return parent;
}
}
Note that you can only use enum values that were declared lexically before the one you're trying to declare, so this only works if your relationships form an acyclic directed graph (and the order you declare them is a valid topological sort).