001/* 002 * Copyright (C) 2007 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package com.google.common.collect; 018 019import com.google.common.annotations.GwtCompatible; 020import com.google.errorprone.annotations.CanIgnoreReturnValue; 021import java.util.Map; 022import javax.annotation.Nullable; 023 024/** 025 * A map, each entry of which maps a Java 026 * <a href="http://tinyurl.com/2cmwkz">raw type</a> to an instance of that type. 027 * In addition to implementing {@code Map}, the additional type-safe operations 028 * {@link #putInstance} and {@link #getInstance} are available. 029 * 030 * <p>Like any other {@code Map<Class, Object>}, this map may contain entries 031 * for primitive types, and a primitive type and its corresponding wrapper type 032 * may map to different values. 033 * 034 * <p>See the Guava User Guide article on <a href= 035 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap"> 036 * {@code ClassToInstanceMap}</a>. 037 * 038 * <p>To map a generic type to an instance of that type, use {@link 039 * com.google.common.reflect.TypeToInstanceMap} instead. 040 * 041 * @param <B> the common supertype that all entries must share; often this is 042 * simply {@link Object} 043 * 044 * @author Kevin Bourrillion 045 * @since 2.0 046 */ 047@GwtCompatible 048public interface ClassToInstanceMap<B> extends Map<Class<? extends B>, B> { 049 /** 050 * Returns the value the specified class is mapped to, or {@code null} if no 051 * entry for this class is present. This will only return a value that was 052 * bound to this specific class, not a value that may have been bound to a 053 * subtype. 054 */ 055 @CanIgnoreReturnValue // TODO(kak): Consider removing this? 056 <T extends B> T getInstance(Class<T> type); 057 058 /** 059 * Maps the specified class to the specified value. Does <i>not</i> associate 060 * this value with any of the class's supertypes. 061 * 062 * @return the value previously associated with this class (possibly {@code 063 * null}), or {@code null} if there was no previous entry. 064 */ 065 @CanIgnoreReturnValue 066 <T extends B> T putInstance(Class<T> type, @Nullable T value); 067}