Java tutorial
//package com.java2s; // This source code is available under the terms of the Affero General Public License v3. import java.util.IdentityHashMap; import java.util.Map; public class Main { public static <K, V> Map<K, V> makeIdentityMap() { return new IdentityHashMap<K, V>(); } public static <K, V> Map<K, V> makeIdentityMap(int size) { return new IdentityHashMap<K, V>(size); } public static <K, V> Map<K, V> makeIdentityMap(Map<? extends K, ? extends V> map) { return new IdentityHashMap<K, V>(map); } }