Java tutorial
//package com.java2s; import java.util.Map; import java.util.Set; public class Main { public static <K, V> K getKeyByValue(Map<K, V> map, V value) { Set<Map.Entry<K, V>> entrySet = map.entrySet(); for (Map.Entry<K, V> entry : entrySet) { if ((entry.getValue() == value) || ((entry.getValue() != null) && (entry.getValue().equals(value)))) { return entry.getKey(); } } return null; } }