| /* |
| * Copyright (C) 2007 Google Inc. |
| * |
| * 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.inject.internal.util; |
| |
| import com.google.inject.internal.Nullable; |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.IdentityHashMap; |
| import java.util.LinkedHashMap; |
| import java.util.Map; |
| import java.util.Map.Entry; |
| import java.util.TreeMap; |
| |
| /** |
| * Static utility methods pertaining to {@link Map} instances. Also see this |
| * class's counterparts {@link Lists} and {@link Sets}. |
| * |
| * @author Kevin Bourrillion |
| * @author Mike Bostock |
| * @author Isaac Shum |
| */ |
| public final class Maps { |
| private Maps() {} |
| |
| /** |
| * Creates a {@code HashMap} instance. |
| * |
| * <p><b>Note:</b> if you don't actually need the resulting map to be mutable, |
| * use {@link Collections#emptyMap} instead. |
| * |
| * @return a new, empty {@code HashMap} |
| */ |
| public static <K, V> HashMap<K, V> newHashMap() { |
| return new HashMap<K, V>(); |
| } |
| |
| /** |
| * Creates an insertion-ordered {@code LinkedHashMap} instance. |
| * |
| * @return a new, empty {@code LinkedHashMap} |
| */ |
| public static <K, V> LinkedHashMap<K, V> newLinkedHashMap() { |
| return new LinkedHashMap<K, V>(); |
| } |
| |
| /** |
| * Creates a {@code TreeMap} instance using the natural ordering of its |
| * elements. |
| * |
| * @return a new, empty {@code TreeMap} |
| */ |
| @SuppressWarnings("unchecked") // allow ungenerified Comparable types |
| public static <K extends Comparable, V> TreeMap<K, V> newTreeMap() { |
| return new TreeMap<K, V>(); |
| } |
| |
| /** |
| * Creates an {@code IdentityHashMap} instance. |
| * |
| * @return a new, empty {@code IdentityHashMap} |
| */ |
| public static <K, V> IdentityHashMap<K, V> newIdentityHashMap() { |
| return new IdentityHashMap<K, V>(); |
| } |
| |
| /** |
| * Returns an immutable map entry with the specified key and value. The {@link |
| * Entry#setValue} operation throws an {@link UnsupportedOperationException}. |
| * |
| * <p>The returned entry is serializable. |
| * |
| * @param key the key to be associated with the returned entry |
| * @param value the value to be associated with the returned entry |
| */ |
| public static <K, V> Entry<K, V> immutableEntry( |
| @Nullable final K key, @Nullable final V value) { |
| return new ImmutableEntry<K, V>(key, value); |
| } |
| } |