EnumSet from array, shortest variant?
Just an alternative. Same amount of code, except no need converting to list, using EnumSet.of() :
EnumSet<Options> temp = options.length > 0 ?
EnumSet.of(options[0], options) :
EnumSet.noneOf(Options.class);
No worries that first element is repeated(it won't be duplicated in a set anyway), no performance gain or penalties as well.
This is two lines, but slightly less complex:
EnumSet<Options> temp = EnumSet.noneOf(Options.class); // make an empty enumset
temp.addAll(Arrays.asList(options)); // add varargs to it
I don't consider this worse than any other kind of variable declaration for a class which doesn't have the constructor you want:
SomeClass variable = new SomeClass(); // make an empty object
variable.addStuff(stuff); // add stuff to it
Guava has factory methods for these kinds of situations: It still needs the call to Arrays.asList but at least it's readable.
import com.google.common.collect.Sets;
EnumSet<Options> temp = Sets.newEnumSet(Arrays.asList(options), Options.class);
You can also do this with Java8 streams and your own CollectionFactory:
EnumSet<Options> temp = Arrays.stream(options)
.collect(Collectors.toCollection(() -> EnumSet.noneOf(Options.class)));