Here you can find the source of asList(final Collection extends T> collection)
@SuppressWarnings("unchecked") public static <T> List<T> asList(final Collection<? extends T> collection)
//package com.java2s; /******************************************************************************* * Copyright (c) 2010-2014 Alexander Kerner. All rights reserved. * * 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./*from w w w. j av a2 s. c o m*/ ******************************************************************************/ import java.util.ArrayList; import java.util.Arrays; import java.util.Collection; import java.util.List; public class Main { @SuppressWarnings("unchecked") public static <T> List<T> asList(final Collection<? extends T> collection) { List<T> result; if (collection instanceof List) { result = (List<T>) collection; } else { result = newList(collection); } return result; } public static <T> List<T> newList() { return new ArrayList<T>(); } public static <T> List<T> newList(final Collection<? extends T> elements) { return new ArrayList<T>(elements); } public static <T> List<T> newList(final Collection<? extends T>... elements) { final List<T> result = newList(); for (final Collection<? extends T> c : elements) { result.addAll(c); } return result; } public static <T> List<T> newList(final T... elements) { return Arrays.asList(elements); } }