Java tutorial
//package com.java2s; /******************************************************************************* * Breakout Cave Survey Visualizer * * Copyright (C) 2014 James Edwards * * jedwards8 at fastmail dot fm * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program 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 General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. *******************************************************************************/ import java.util.LinkedHashMap; import java.util.Map; import java.util.function.Function; import java.util.stream.Stream; public class Main { public static <K, V> Map<K, V> keyify(Stream<? extends V> stream, Function<? super V, K> keyAssigner) { Map<K, V> result = new LinkedHashMap<>(); stream.forEach(v -> result.put(keyAssigner.apply(v), v)); return result; } }