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/*
* Copyright (C) 2015 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 com.android.tv.common;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
/**
* Static utilities for collections
*/
public class CollectionUtils {
/**
* Returns an array with the arrays concatenated together.
*
* @see <a href="http://stackoverflow.com/a/784842/1122089">Stackoverflow answer</a> by
* <a href="http://stackoverflow.com/users/40342/joachim-sauer">Joachim Sauer</a>
*/
public static <T> T[] concatAll(T[] first, T[]... rest) {
int totalLength = first.length;
for (T[] array : rest) {
totalLength += array.length;
}
T[] result = Arrays.copyOf(first, totalLength);
int offset = first.length;
for (T[] array : rest) {
System.arraycopy(array, 0, result, offset, array.length);
offset += array.length;
}
return result;
}
/**
* Unions the two collections and returns the unified list.
* <p>
* The elements is not compared with hashcode() or equals(). Comparator is used for the equality
* check.
*/
public static <T> List<T> union(Collection<T> originals, Collection<T> toAdds,
Comparator<T> comparator) {
List<T> result = new ArrayList<>(originals);
Collections.sort(result, comparator);
List<T> resultToAdd = new ArrayList<>();
for (T toAdd : toAdds) {
if (Collections.binarySearch(result, toAdd, comparator) < 0) {
resultToAdd.add(toAdd);
}
}
result.addAll(resultToAdd);
return result;
}
/**
* Subtracts the elements from the original collection.
*/
public static <T> List<T> subtract(Collection<T> originals, T[] toSubtracts,
Comparator<T> comparator) {
List<T> result = new ArrayList<>(originals);
Collections.sort(result, comparator);
for (T toSubtract : toSubtracts) {
int index = Collections.binarySearch(result, toSubtract, comparator);
if (index >= 0) {
result.remove(index);
}
}
return result;
}
/**
* Returns {@code true} if the two specified collections have common elements.
*/
public static <T> boolean containsAny(Collection<T> c1, Collection<T> c2,
Comparator<T> comparator) {
List<T> contains = new ArrayList<>(c1);
Collections.sort(contains, comparator);
for (T iterate : c2) {
if (Collections.binarySearch(contains, iterate, comparator) >= 0) {
return true;
}
}
return false;
}
}
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