/*
* Copyright (c) 2013-2017 Cinchapi Inc.
*
* 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.cinchapi.concourse.util;
import java.lang.reflect.Array;
import java.util.List;
import com.google.common.base.Preconditions;
/**
* Utilities for Lists.
*
* @author Jeff Nelson
*/
public final class TLists {
/**
* Modify each list to retain only the elements that are contained in all of
* the lists.
*
* @param lists
*/
@SafeVarargs
public static void retainIntersection(List<?>... lists) {
Preconditions.checkArgument(lists.length > 0);
List<?> intersection = lists[0];
for (int i = 1; i < lists.length; ++i) {
intersection.retainAll(lists[i]);
}
for (int i = 1; i < lists.length; ++i) {
lists[i].retainAll(intersection);
}
}
/**
* Syntactic sugar for transforming a generic {@link List} into an array
* with the same generic type. This method performs the casting so that the
* calling code doesn't have to.
*
* @param list
* @return the array
*/
@SuppressWarnings("unchecked")
public static <T> T[] toArrayCasted(List<T> list, Class<T> clazz) {
return (T[]) list.toArray((T[]) Array.newInstance(clazz, 0));
}
private TLists() {/* noop */}
}