120 lines
3.8 KiB
Java
120 lines
3.8 KiB
Java
/*
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* Copyright (C) 2007 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.android.collect;
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import android.compat.annotation.UnsupportedAppUsage;
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import android.os.Build;
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import android.util.ArraySet;
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import java.util.Collections;
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import java.util.EnumSet;
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import java.util.HashSet;
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import java.util.SortedSet;
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import java.util.TreeSet;
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/**
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* Provides static methods for creating mutable {@code Set} instances easily and
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* other static methods for working with Sets.
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*
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*/
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@android.ravenwood.annotation.RavenwoodKeepWholeClass
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public class Sets {
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/**
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* Creates an empty {@code HashSet} instance.
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*
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* <p><b>Note:</b> if {@code E} is an {@link Enum} type, use {@link
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* EnumSet#noneOf} instead.
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*
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* <p><b>Note:</b> if you only need an <i>immutable</i> empty Set,
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* use {@link Collections#emptySet} instead.
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*
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* @return a newly-created, initially-empty {@code HashSet}
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*/
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@UnsupportedAppUsage
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public static <K> HashSet<K> newHashSet() {
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return new HashSet<K>();
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}
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/**
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* Creates a {@code HashSet} instance containing the given elements.
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*
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* <p><b>Note:</b> due to a bug in javac 1.5.0_06, we cannot support the
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* following:
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*
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* <p>{@code Set<Base> set = Sets.newHashSet(sub1, sub2);}
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*
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* <p>where {@code sub1} and {@code sub2} are references to subtypes of {@code
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* Base}, not of {@code Base} itself. To get around this, you must use:
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*
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* <p>{@code Set<Base> set = Sets.<Base>newHashSet(sub1, sub2);}
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*
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* @param elements the elements that the set should contain
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* @return a newly-created {@code HashSet} containing those elements (minus
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* duplicates)
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*/
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@UnsupportedAppUsage
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public static <E> HashSet<E> newHashSet(E... elements) {
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int capacity = elements.length * 4 / 3 + 1;
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HashSet<E> set = new HashSet<E>(capacity);
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Collections.addAll(set, elements);
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return set;
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}
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/**
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* Creates an empty {@code SortedSet} instance.
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*
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* @return a newly-created, initially-empty {@code SortedSet}.
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*/
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@UnsupportedAppUsage
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public static <E> SortedSet<E> newSortedSet() {
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return new TreeSet<E>();
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}
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/**
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* Creates a {@code SortedSet} instance containing the given elements.
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*
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* @param elements the elements that the set should contain
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* @return a newly-created {@code SortedSet} containing those elements (minus
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* duplicates)
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*/
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public static <E> SortedSet<E> newSortedSet(E... elements) {
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SortedSet<E> set = new TreeSet<E>();
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Collections.addAll(set, elements);
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return set;
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}
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/**
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* Creates a {@code ArraySet} instance.
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*/
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@UnsupportedAppUsage
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public static <E> ArraySet<E> newArraySet() {
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return new ArraySet<E>();
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}
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/**
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* Creates a {@code ArraySet} instance containing the given elements.
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*/
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@UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
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public static <E> ArraySet<E> newArraySet(E... elements) {
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int capacity = elements.length * 4 / 3 + 1;
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ArraySet<E> set = new ArraySet<E>(capacity);
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Collections.addAll(set, elements);
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return set;
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}
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}
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