11d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert/* 21d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * Copyright (C) 2007 The Guava Authors 31d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 41d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * Licensed under the Apache License, Version 2.0 (the "License"); 51d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * you may not use this file except in compliance with the License. 61d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * You may obtain a copy of the License at 71d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 81d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * http://www.apache.org/licenses/LICENSE-2.0 91d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 101d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * Unless required by applicable law or agreed to in writing, software 111d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * distributed under the License is distributed on an "AS IS" BASIS, 121d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 131d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * See the License for the specific language governing permissions and 141d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * limitations under the License. 151d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert */ 161d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 171d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringertpackage com.google.common.collect; 181d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 191d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringertimport com.google.common.annotations.Beta; 201d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 211d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert/** 221d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * Provides equivalent behavior to {@link String#intern} for other immutable 231d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * types. 241d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 251d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * @author Kevin Bourrillion 261d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * @since 3.0 271d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert */ 281d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert@Beta 291d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringertpublic interface Interner<E> { 301d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert /** 311d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * Chooses and returns the representative instance for any of a collection of 321d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * instances that are equal to each other. If two {@linkplain Object#equals 331d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * equal} inputs are given to this method, both calls will return the same 341d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * instance. That is, {@code intern(a).equals(a)} always holds, and {@code 351d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * intern(a) == intern(b)} if and only if {@code a.equals(b)}. Note that 361d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * {@code intern(a)} is permitted to return one instance now and a different 371d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * instance later if the original interned instance was garbage-collected. 381d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 391d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * <p><b>Warning:</b> do not use with mutable objects. 401d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 411d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * @throws NullPointerException if {@code sample} is null 421d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert */ 431d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert E intern(E sample); 441d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert} 45