Java Utililty Methods Set sub set

if (s == null)
    return null;
String sub = s.trim();
int endIndex = -1;
if (delimiters != null) {
    Iterator<String> iter = delimiters.iterator();
    while (iter.hasNext()) {
        String delimiter = iter.next();
...

List<Set<T>> subsets = new ArrayList<Set<T>>();
List<T> list = new ArrayList<T>(set);
int numOfSubsets = 1 << set.size();
for (int i = 0; i < numOfSubsets; i++) {
    Set<T> subset = new HashSet<T>();
    for (int j = 0; j < numOfSubsets; j++) {
        if (((i >> j) & 1) == 1) {
            subset.add(list.get(j));
...

if (subsetSize <= 0) {
    throw new IllegalArgumentException("Incorrect max size");
if (original == null || original.isEmpty()) {
    return Collections.emptyList();
int subsetCount = (int) (Math.ceil((double) original.size() / subsetSize));
ArrayList<Set<T>> subsets = new ArrayList<Set<T>>(subsetCount);
...

if (a == null)
    return Collections.EMPTY_SET;
if (b == null)
    return new HashSet<Object>(a);
Set<Object> sub = new HashSet<Object>();
for (Object obj : a) {
    if (!b.contains(obj))
        sub.add(obj);
...

assert vals.length == select.length;
List<Double> list = new ArrayList<Double>();
for (int i = 0; i < vals.length; i++) {
    if (select[i] && !Double.isNaN(vals[i]))
        list.add(vals[i]);
double[] sub = new double[list.size()];
int i = 0;
...

for (Iterator i = sub.iterator(); i.hasNext();) {
    if (!sup.contains(i.next()))
        return false;
return true;

Set<T> result = new HashSet<T>(nn);
result.remove(n);
return result;