Here you can find the source of toList(Iterable
static List<String> toList(Iterable<String> protocols)
//package com.java2s; /*// w w w . j ava2s . com * Copyright 2014 The Netty Project * * The Netty Project licenses this file to you 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. */ import java.util.ArrayList; import java.util.List; public class Main { private static final int DEFAULT_LIST_SIZE = 2; static List<String> toList(Iterable<String> protocols) { return toList(DEFAULT_LIST_SIZE, protocols); } static List<String> toList(int initialListSize, Iterable<String> protocols) { if (protocols == null) { return null; } List<String> result = new ArrayList<String>(initialListSize); for (String p : protocols) { if (p == null || p.isEmpty()) { throw new IllegalArgumentException( "protocol cannot be null or empty"); } result.add(p); } if (result.isEmpty()) { throw new IllegalArgumentException("protocols cannot empty"); } return result; } static List<String> toList(String... protocols) { return toList(DEFAULT_LIST_SIZE, protocols); } static List<String> toList(int initialListSize, String... protocols) { if (protocols == null) { return null; } List<String> result = new ArrayList<String>(initialListSize); for (String p : protocols) { if (p == null || p.isEmpty()) { throw new IllegalArgumentException( "protocol cannot be null or empty"); } result.add(p); } if (result.isEmpty()) { throw new IllegalArgumentException("protocols cannot empty"); } return result; } }