Java tutorial
//package com.java2s; /******************************************************************************* * Copyright (c) 2012-2015 Codenvy, S.A. * 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 * * Contributors: * Codenvy, S.A. - initial API and implementation *******************************************************************************/ import java.util.HashSet; import java.util.Map; import java.util.Set; public class Main { /** * Look up giving map for giving value collect pick all suitable keys * @param map * @param value * @return ste of keys mapped to the giving value */ 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; } }