Java tutorial
//package com.java2s; /** * Copyright (c) 2014-2015 by Wen Yu. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Any modifications to this file must keep this entire header intact. */ import java.util.Map; import java.util.Set; import java.util.HashSet; public class Main { public static <T, E> Set<T> getKeysByValue(Map<T, E> map, E value) { Set<T> keys = new HashSet<T>(); for (Map.Entry<T, E> entry : map.entrySet()) { if (value.equals(entry.getValue())) { keys.add(entry.getKey()); } } return keys; } }