| /* |
| * Copyright (C) 2008 The Guava Authors |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.google.common.collect; |
| |
| import com.google.common.annotations.GwtCompatible; |
| |
| import javax.annotation.Nullable; |
| |
| /** |
| * Bimap with no mappings. |
| * |
| * @author Jared Levy |
| */ |
| @GwtCompatible(emulated = true) |
| @SuppressWarnings("serial") // uses writeReplace(), not default serialization |
| final class EmptyImmutableBiMap extends ImmutableBiMap<Object, Object> { |
| static final EmptyImmutableBiMap INSTANCE = new EmptyImmutableBiMap(); |
| |
| private EmptyImmutableBiMap() {} |
| |
| @Override public ImmutableBiMap<Object, Object> inverse() { |
| return this; |
| } |
| |
| @Override |
| public int size() { |
| return 0; |
| } |
| |
| @Override |
| public boolean isEmpty() { |
| return true; |
| } |
| |
| @Override |
| public Object get(@Nullable Object key) { |
| return null; |
| } |
| |
| @Override |
| public ImmutableSet<Entry<Object, Object>> entrySet() { |
| return ImmutableSet.of(); |
| } |
| |
| @Override |
| ImmutableSet<Entry<Object, Object>> createEntrySet() { |
| throw new AssertionError("should never be called"); |
| } |
| |
| @Override |
| public ImmutableSetMultimap<Object, Object> asMultimap() { |
| return ImmutableSetMultimap.of(); |
| } |
| |
| @Override |
| public ImmutableSet<Object> keySet() { |
| return ImmutableSet.of(); |
| } |
| |
| @Override |
| boolean isPartialView() { |
| return false; |
| } |
| |
| Object readResolve() { |
| return INSTANCE; // preserve singleton property |
| } |
| } |