SetUtils, simple utils in order to convert to sorted sets, and sets from list and array.

SetUtils.java

import java.lang.reflect.Array;
import java.util.*;

/**
 * @author <a href="mailto:vegaasen@gmail.com">Vegard Aasen</a>
 * @since 3:13 PM
 */
public final class SetUtils {

    private static final String EMPTY = "";

    private SetUtils() {
    }

    public static <T> Set<T> toSet(final T[] arr) {
        return toSet(Arrays.asList(arr));
    }

    public static <T> Set<T> toSet(final List<T> list) {
        if (list == null || list.isEmpty()) {
            return Collections.emptySet();
        }
        Set<T> set = new HashSet<>();
        set.addAll(list);
        return set;
    }

    @SuppressWarnings("unchecked")
    public static <T> T[] toSortedSet(final Set<T> set, final Class<?> type) {
        return toSortedSet(set, type, new Comparator<T>() {
            @Override
            public int compare(final T s0, final T s1) {
                return s0.toString().compareToIgnoreCase(s1.toString());
            }
        });
    }

    @SuppressWarnings("unchecked")
    public static <T> T[] toSortedSet(final Set<T> set, final Class<?> type, Comparator<T> comparator) {
        if (set == null || set.isEmpty()) {
            return (T[]) Array.newInstance(type, 0);
        }
        final T[] array = set.toArray((T[]) Array.newInstance(type, set.size()));
        Arrays.sort(array, comparator);
        return array;
    }

    public static String getAsSeparatedList(Set<?> obs) {
        if (obs == null) {
            return EMPTY;
        }
        StringBuilder bb = new StringBuilder();
        int c = 0;
        for (Object o : obs) {
            if (o != null) {
                bb.append(o.toString());
                if (c != obs.size()) {
                    bb.append(",");
                }
                c++;
            }
        }
        return bb.toString();
    }

}