将键值对的列表转换为映射，并始终插入第一个重复键，或始终插入最后一个重复键。
/******************************************************************************* * Copyright (c) 2008, 2010 Xuggle Inc. All rights reserved. * * This file is part of Xuggle-Utils. * * Xuggle-Utils is free software: you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * Xuggle-Utils is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with Xuggle-Utils. If not, see <http://www.gnu.org/licenses/>. *******************************************************************************//** from N o w J a v a . c o m - 时代Java**/ import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Set; import java.util.Map.Entry; public class Main{ /** * Converts a list of key-value pairs into a {@link Map}, with either * the first duplicate key always being inserted, or the last duplicate key * always being inserted. * * @param list * The list of name value pairs to convert. * @param mapToFill * The map to fill. This method will empty the list first. * @param mode * How duplicate values in <code>list</code> should be treated. */ public static void listToMap(final List<? extends IKeyValuePair> list, final Map<String, String> mapToFill, final ListToMapMode mode) { if (list == null)/** 来 自 nowjava.com - 时代Java**/ throw new IllegalArgumentException(); if (mapToFill == null) throw new IllegalArgumentException(); mapToFill.clear(); for (IKeyValuePair pair : list) { if (pair != null) { final String key = pair.getKey(); final String value = pair.getValue(); if (mode == ListToMapMode.FIRST_WINS) { if (mapToFill.containsKey(key)) continue; } if (mode == ListToMapMode.FIRST_NONEMPTY_WINS) { if (mapToFill.containsKey(key)) { final String oldValue = mapToFill.get(key); if (oldValue != null && oldValue.length() > 0) // the list has a non-null value; don't reset it. continue; } } if (mode == ListToMapMode.LAST_NONEMPTY_WINS) { if (value == null || value.length() == 0) { if (mapToFill.containsKey(key)) // already contains an empty key continue; } } mapToFill.put(key, value); } } }