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/*
* Copyright (C) 2007 Google 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.google.inject.internal.util;
import com.google.inject.internal.Nullable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
/**
* Static utility methods pertaining to {@link List} instances. Also see this
* class's counterparts {@link Sets} and {@link Maps}.
*
* @author Kevin Bourrillion
* @author Mike Bostock
*/
public final class Lists {
private Lists() {}
// ArrayList
/**
* Creates an empty {@code ArrayList} instance.
*
* <p><b>Note:</b> if you need an immutable empty list, use {@link
* Collections#emptyList} instead.
*
* @return a new, empty {@code ArrayList}
*/
public static <E> ArrayList<E> newArrayList() {
return new ArrayList<E>();
}
/**
* Creates an {@code ArrayList} instance containing the given elements.
*
* <p><b>Note:</b> if you need an immutable List, use {@link ImmutableList}
* instead.
*
* <p><b>Note:</b> due to a bug in javac 1.5.0_06, we cannot support the
* following:
*
* <p>{@code List<Base> list = Lists.newArrayList(sub1, sub2);}
*
* <p>where {@code sub1} and {@code sub2} are references to subtypes of {@code
* Base}, not of {@code Base} itself. To get around this, you must use:
*
* <p>{@code List<Base> list = Lists.<Base>newArrayList(sub1, sub2);}
*
* @param elements the elements that the list should contain, in order
* @return a new {@code ArrayList} containing those elements
*/
public static <E> ArrayList<E> newArrayList(E... elements) {
// Avoid integer overflow when a large array is passed in
int capacity = computeArrayListCapacity(elements.length);
ArrayList<E> list = new ArrayList<E>(capacity);
Collections.addAll(list, elements);
return list;
}
static int computeArrayListCapacity(int arraySize) {
Preconditions.checkArgument(arraySize >= 0);
// TODO: Figure out the right behavior, and document it
return (int) Math.min(5L + arraySize + (arraySize / 10), Integer.MAX_VALUE);
}
/**
* Creates an {@code ArrayList} instance containing the given elements.
*
* @param elements the elements that the list should contain, in order
* @return a new {@code ArrayList} containing those elements
*/
public static <E> ArrayList<E> newArrayList(Iterable<? extends E> elements) {
// Let ArrayList's sizing logic work, if possible
if (elements instanceof Collection) {
@SuppressWarnings("unchecked")
Collection<? extends E> collection = (Collection<? extends E>) elements;
return new ArrayList<E>(collection);
} else {
return newArrayList(elements.iterator());
}
}
/**
* Creates an {@code ArrayList} instance containing the given elements.
*
* @param elements the elements that the list should contain, in order
* @return a new {@code ArrayList} containing those elements
*/
public static <E> ArrayList<E> newArrayList(Iterator<? extends E> elements) {
ArrayList<E> list = newArrayList();
while (elements.hasNext()) {
list.add(elements.next());
}
return list;
}
/**
* Returns an unmodifiable list containing the specified first element and
* the additional elements.
*/
public static <E> ArrayList<E> newArrayList(@Nullable E first, E[] rest) {
ArrayList<E> result = new ArrayList<E>(rest.length + 1);
result.add(first);
for (E element : rest) {
result.add(element);
}
return result;
}
}
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