Java Code Examples for java.util.Collections.emptySortedMap()

/**
 * Performs a deep copy of the supplied {@link Map} such that the
 * {@link SortedMap} returned has copies of the supplied {@link
 * Map}'s {@linkplain Map#values() values}.
 *
 * <p>This method may return {@code null} if {@code source} is
 * {@code null}.</p>
 *
 * <p>The {@link SortedMap} returned by this method is
 * mutable.</p>
 *
 * @param source the {@link Map} to copy; may be {@code null} in
 * which case {@code null} will be returned
 *
 * @return a mutable {@link SortedMap}, or {@code null}
 */
private static final SortedMap<String, SortedSet<Entry>> deepCopy(final Map<? extends String, ? extends SortedSet<Entry>> source) {
  final SortedMap<String, SortedSet<Entry>> returnValue;
  if (source == null) {
    returnValue = null;
  } else if (source.isEmpty()) {
    returnValue = Collections.emptySortedMap();
  } else {
    returnValue = new TreeMap<>();
    final Collection<? extends Map.Entry<? extends String, ? extends SortedSet<Entry>>> entrySet = source.entrySet();
    if (entrySet != null && !entrySet.isEmpty()) {
      for (final Map.Entry<? extends String, ? extends SortedSet<Entry>> entry : entrySet) {
        final String key = entry.getKey();
        final SortedSet<Entry> value = entry.getValue();
        if (value == null) {
          returnValue.put(key, null);
        } else {
          final SortedSet<Entry> newValue = new TreeSet<>(value.comparator());
          newValue.addAll(value);
          returnValue.put(key, newValue);
        }
      }
    }
  }
  return returnValue;
}
 

/**
 * Creates a new {@link Index}.
 *
 * @param entries a {@link Map} of {@link SortedSet}s of {@link
 * Entry} objects indexed by the name of the Helm chart they
 * describe; may be {@code null}; copied by value
 */
Index(final Map<? extends String, ? extends SortedSet<Entry>> entries) {
  super();
  if (entries == null || entries.isEmpty()) {
    this.entries = Collections.emptySortedMap();
  } else {
    this.entries = Collections.unmodifiableSortedMap(deepCopy(entries));
  }
}