I need to get the element type of an empty EnumSet at runtime. Is this possible? I see that EnumSet has a private field called elementType which stores the type of Enum in the set. Unfortunately, this isn't exposed, which is an odd decision on Sun's part IMHO.
Any other trick to get the element type? The generics information isn't available at runtime, only at compile-time...
Thanks!
Dustin
Even complementOf does not work because it does not compile at all.
import java.util.*;
enum Colors {
RED, BLUE, WHITE
};
enum Numbers {
ONE, TWO, THREE
}
class TestEnumSet {
public static void printEnumType (EnumSet <?> en) {
System.out.println (en);
System.out.println (EnumSet.complementOf (en)); // does not compile
}
public static void main(String[] args) {
printEnumType (EnumSet.noneOf (Colors.class));
printEnumType (EnumSet.noneOf (Numbers.class));
}
}
Error:
TestEnum.java:13: <E>complementOf(java.util.EnumSet<E>) in java.util.EnumSet can
not be applied to (java.util.EnumSet<capture of ?>)
System.out.println (EnumSet.complementOf (en)); // does not compile
> Even complementOf does not work because it does not compile at all.
This might be a javac compiler bug. The same code compiles and runs fine in Eclipse 3.1.
I haven't thought about this carefully, but I was under the impression that capture conversion could deal with this case. Will take a closer look.
