Best way to check if list contains at least one of an enum

Question

I have an enum :

public enum PermissionsEnum {
    ABC("Abc"),        
    XYZ("Xyz"),
    ....
}

And then I have a list of Strings. I want to check if my list has at least one of the enums. I currently check it by an iterative approach. I also know there is a way to do it by using || checking list.contains(enum.ABC..) || list.contains(enum.XYZ) || ....

Is there a better way to do it?

Answer 1

A List<String> never contains a PermissionsEnum value.

The condition list.contains(enum.ABC) || list.contains(enum.XYZ) is not going to be working.

Instead, you could map PermissionsEnum.values() to a Stream<String> and call Stream#anyMatch on it:

boolean result = Arrays.stream(PermissionsEnum.values())
                       .map(PermissionsEnum::getValue)
                       .anyMatch(list::contains);

*I assumed that constructor parameter is accessible by the getValue method.

---

In case the list is large (a few iterations over it might take a lot of time) we could optimise the previous snippet a bit and iterate over the list once:

Set<String> values = Arrays.stream(PermissionsEnum.values())
                           .map(PermissionsEnum::getValue)
                           .collect(Collectors.toSet());

boolean result = list.stream().anyMatch(values::contains);

Answer 2

You can do it easily in an iterative way with a for loop.

boolean contains = false;
for (PermissionsEnum permission : PermissionsEnum.values()) {
    if (list.contains(permission.getName())) {
        contains = true;
        break;
    }
}

Or you can use Collections.disjoint() like this:

Set<String> permissionsNames = Stream.of(PermissionsEnum.values())
                                     .map(PermissionsEnum::getName())
                                     .collect(Collectors.toSet());

boolean contains = !Collections.disjoint(list, permissionsNames);

PS: getName() must retrieve the constructor value.