| /* |
| * Copyright (C) 2010 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package libcore.util; |
| |
| import java.lang.ref.Reference; |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.Comparator; |
| import java.util.Iterator; |
| import java.util.List; |
| |
| public final class CollectionUtils { |
| private CollectionUtils() {} |
| |
| /** |
| * Returns an iterator over the values referenced by the elements of {@code |
| * iterable}. |
| * |
| * @param trim true to remove reference objects from the iterable after |
| * their referenced values have been cleared. |
| */ |
| public static <T> Iterable<T> dereferenceIterable( |
| final Iterable<? extends Reference<T>> iterable, final boolean trim) { |
| return new Iterable<T>() { |
| public Iterator<T> iterator() { |
| return new Iterator<T>() { |
| private final Iterator<? extends Reference<T>> delegate = iterable.iterator(); |
| private boolean removeIsOkay; |
| private T next; |
| |
| private void computeNext() { |
| removeIsOkay = false; |
| while (next == null && delegate.hasNext()) { |
| next = delegate.next().get(); |
| if (trim && next == null) { |
| delegate.remove(); |
| } |
| } |
| } |
| |
| @Override public boolean hasNext() { |
| computeNext(); |
| return next != null; |
| } |
| |
| @Override public T next() { |
| if (!hasNext()) { |
| throw new IllegalStateException(); |
| } |
| T result = next; |
| removeIsOkay = true; |
| next = null; |
| return result; |
| } |
| |
| public void remove() { |
| if (!removeIsOkay) { |
| throw new IllegalStateException(); |
| } |
| delegate.remove(); |
| } |
| }; |
| } |
| }; |
| } |
| |
| /** |
| * Sorts and removes duplicate elements from {@code list}. This method does |
| * not use {@link Object#equals}: only the comparator defines equality. |
| */ |
| public static <T> void removeDuplicates(List<T> list, Comparator<? super T> comparator) { |
| Collections.sort(list, comparator); |
| int j = 1; |
| for (int i = 1; i < list.size(); i++) { |
| if (comparator.compare(list.get(j - 1), list.get(i)) != 0) { |
| T object = list.get(i); |
| list.set(j++, object); |
| } |
| } |
| if (j < list.size()) { |
| list.subList(j, list.size()).clear(); |
| } |
| } |
| } |