| /* |
| * Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.util; |
| |
| /** |
| * A collection that contains no duplicate elements. More formally, sets |
| * contain no pair of elements {@code e1} and {@code e2} such that |
| * {@code e1.equals(e2)}, and at most one null element. As implied by |
| * its name, this interface models the mathematical <i>set</i> abstraction. |
| * |
| * <p>The {@code Set} interface places additional stipulations, beyond those |
| * inherited from the {@code Collection} interface, on the contracts of all |
| * constructors and on the contracts of the {@code add}, {@code equals} and |
| * {@code hashCode} methods. Declarations for other inherited methods are |
| * also included here for convenience. (The specifications accompanying these |
| * declarations have been tailored to the {@code Set} interface, but they do |
| * not contain any additional stipulations.) |
| * |
| * <p>The additional stipulation on constructors is, not surprisingly, |
| * that all constructors must create a set that contains no duplicate elements |
| * (as defined above). |
| * |
| * <p>Note: Great care must be exercised if mutable objects are used as set |
| * elements. The behavior of a set is not specified if the value of an object |
| * is changed in a manner that affects {@code equals} comparisons while the |
| * object is an element in the set. A special case of this prohibition is |
| * that it is not permissible for a set to contain itself as an element. |
| * |
| * <p>Some set implementations have restrictions on the elements that |
| * they may contain. For example, some implementations prohibit null elements, |
| * and some have restrictions on the types of their elements. Attempting to |
| * add an ineligible element throws an unchecked exception, typically |
| * {@code NullPointerException} or {@code ClassCastException}. Attempting |
| * to query the presence of an ineligible element may throw an exception, |
| * or it may simply return false; some implementations will exhibit the former |
| * behavior and some will exhibit the latter. More generally, attempting an |
| * operation on an ineligible element whose completion would not result in |
| * the insertion of an ineligible element into the set may throw an |
| * exception or it may succeed, at the option of the implementation. |
| * Such exceptions are marked as "optional" in the specification for this |
| * interface. |
| * |
| * <h2><a id="unmodifiable">Unmodifiable Sets</a></h2> |
| * <p>The {@link Set#of(Object...) Set.of} and |
| * {@link Set#copyOf Set.copyOf} static factory methods |
| * provide a convenient way to create unmodifiable sets. The {@code Set} |
| * instances created by these methods have the following characteristics: |
| * |
| * <ul> |
| * <li>They are <a href="Collection.html#unmodifiable"><i>unmodifiable</i></a>. Elements cannot |
| * be added or removed. Calling any mutator method on the Set |
| * will always cause {@code UnsupportedOperationException} to be thrown. |
| * However, if the contained elements are themselves mutable, this may cause the |
| * Set to behave inconsistently or its contents to appear to change. |
| * <li>They disallow {@code null} elements. Attempts to create them with |
| * {@code null} elements result in {@code NullPointerException}. |
| * <li>They are serializable if all elements are serializable. |
| * <li>They reject duplicate elements at creation time. Duplicate elements |
| * passed to a static factory method result in {@code IllegalArgumentException}. |
| * <li>The iteration order of set elements is unspecified and is subject to change. |
| * <li>They are <a href="../lang/doc-files/ValueBased.html">value-based</a>. |
| * Programmers should treat instances that are {@linkplain #equals(Object) equal} |
| * as interchangeable and should not use them for synchronization, or |
| * unpredictable behavior may occur. For example, in a future release, |
| * synchronization may fail. Callers should make no assumptions |
| * about the identity of the returned instances. Factories are free to |
| * create new instances or reuse existing ones. |
| * <li>They are serialized as specified on the |
| * <a href="{@docRoot}/serialized-form.html#java.util.CollSer">Serialized Form</a> |
| * page. |
| * </ul> |
| * |
| * <p>This interface is a member of the |
| * <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework"> |
| * Java Collections Framework</a>. |
| * |
| * @param <E> the type of elements maintained by this set |
| * |
| * @author Josh Bloch |
| * @author Neal Gafter |
| * @see Collection |
| * @see List |
| * @see SortedSet |
| * @see HashSet |
| * @see TreeSet |
| * @see AbstractSet |
| * @see Collections#singleton(java.lang.Object) |
| * @see Collections#EMPTY_SET |
| * @since 1.2 |
| */ |
| |
| public interface Set<E> extends Collection<E> { |
| // Query Operations |
| |
| /** |
| * Returns the number of elements in this set (its cardinality). If this |
| * set contains more than {@code Integer.MAX_VALUE} elements, returns |
| * {@code Integer.MAX_VALUE}. |
| * |
| * @return the number of elements in this set (its cardinality) |
| */ |
| int size(); |
| |
| /** |
| * Returns {@code true} if this set contains no elements. |
| * |
| * @return {@code true} if this set contains no elements |
| */ |
| boolean isEmpty(); |
| |
| /** |
| * Returns {@code true} if this set contains the specified element. |
| * More formally, returns {@code true} if and only if this set |
| * contains an element {@code e} such that |
| * {@code Objects.equals(o, e)}. |
| * |
| * @param o element whose presence in this set is to be tested |
| * @return {@code true} if this set contains the specified element |
| * @throws ClassCastException if the type of the specified element |
| * is incompatible with this set |
| * (<a href="Collection.html#optional-restrictions">optional</a>) |
| * @throws NullPointerException if the specified element is null and this |
| * set does not permit null elements |
| * (<a href="Collection.html#optional-restrictions">optional</a>) |
| */ |
| boolean contains(Object o); |
| |
| /** |
| * Returns an iterator over the elements in this set. The elements are |
| * returned in no particular order (unless this set is an instance of some |
| * class that provides a guarantee). |
| * |
| * @return an iterator over the elements in this set |
| */ |
| Iterator<E> iterator(); |
| |
| /** |
| * Returns an array containing all of the elements in this set. |
| * If this set makes any guarantees as to what order its elements |
| * are returned by its iterator, this method must return the |
| * elements in the same order. |
| * |
| * <p>The returned array will be "safe" in that no references to it |
| * are maintained by this set. (In other words, this method must |
| * allocate a new array even if this set is backed by an array). |
| * The caller is thus free to modify the returned array. |
| * |
| * <p>This method acts as bridge between array-based and collection-based |
| * APIs. |
| * |
| * @return an array containing all the elements in this set |
| */ |
| Object[] toArray(); |
| |
| /** |
| * Returns an array containing all of the elements in this set; the |
| * runtime type of the returned array is that of the specified array. |
| * If the set fits in the specified array, it is returned therein. |
| * Otherwise, a new array is allocated with the runtime type of the |
| * specified array and the size of this set. |
| * |
| * <p>If this set fits in the specified array with room to spare |
| * (i.e., the array has more elements than this set), the element in |
| * the array immediately following the end of the set is set to |
| * {@code null}. (This is useful in determining the length of this |
| * set <i>only</i> if the caller knows that this set does not contain |
| * any null elements.) |
| * |
| * <p>If this set makes any guarantees as to what order its elements |
| * are returned by its iterator, this method must return the elements |
| * in the same order. |
| * |
| * <p>Like the {@link #toArray()} method, this method acts as bridge between |
| * array-based and collection-based APIs. Further, this method allows |
| * precise control over the runtime type of the output array, and may, |
| * under certain circumstances, be used to save allocation costs. |
| * |
| * <p>Suppose {@code x} is a set known to contain only strings. |
| * The following code can be used to dump the set into a newly allocated |
| * array of {@code String}: |
| * |
| * <pre> |
| * String[] y = x.toArray(new String[0]);</pre> |
| * |
| * Note that {@code toArray(new Object[0])} is identical in function to |
| * {@code toArray()}. |
| * |
| * @param a the array into which the elements of this set are to be |
| * stored, if it is big enough; otherwise, a new array of the same |
| * runtime type is allocated for this purpose. |
| * @return an array containing all the elements in this set |
| * @throws ArrayStoreException if the runtime type of the specified array |
| * is not a supertype of the runtime type of every element in this |
| * set |
| * @throws NullPointerException if the specified array is null |
| */ |
| <T> T[] toArray(T[] a); |
| |
| |
| // Modification Operations |
| |
| /** |
| * Adds the specified element to this set if it is not already present |
| * (optional operation). More formally, adds the specified element |
| * {@code e} to this set if the set contains no element {@code e2} |
| * such that |
| * {@code Objects.equals(e, e2)}. |
| * If this set already contains the element, the call leaves the set |
| * unchanged and returns {@code false}. In combination with the |
| * restriction on constructors, this ensures that sets never contain |
| * duplicate elements. |
| * |
| * <p>The stipulation above does not imply that sets must accept all |
| * elements; sets may refuse to add any particular element, including |
| * {@code null}, and throw an exception, as described in the |
| * specification for {@link Collection#add Collection.add}. |
| * Individual set implementations should clearly document any |
| * restrictions on the elements that they may contain. |
| * |
| * @param e element to be added to this set |
| * @return {@code true} if this set did not already contain the specified |
| * element |
| * @throws UnsupportedOperationException if the {@code add} operation |
| * is not supported by this set |
| * @throws ClassCastException if the class of the specified element |
| * prevents it from being added to this set |
| * @throws NullPointerException if the specified element is null and this |
| * set does not permit null elements |
| * @throws IllegalArgumentException if some property of the specified element |
| * prevents it from being added to this set |
| */ |
| boolean add(E e); |
| |
| |
| /** |
| * Removes the specified element from this set if it is present |
| * (optional operation). More formally, removes an element {@code e} |
| * such that |
| * {@code Objects.equals(o, e)}, if |
| * this set contains such an element. Returns {@code true} if this set |
| * contained the element (or equivalently, if this set changed as a |
| * result of the call). (This set will not contain the element once the |
| * call returns.) |
| * |
| * @param o object to be removed from this set, if present |
| * @return {@code true} if this set contained the specified element |
| * @throws ClassCastException if the type of the specified element |
| * is incompatible with this set |
| * (<a href="Collection.html#optional-restrictions">optional</a>) |
| * @throws NullPointerException if the specified element is null and this |
| * set does not permit null elements |
| * (<a href="Collection.html#optional-restrictions">optional</a>) |
| * @throws UnsupportedOperationException if the {@code remove} operation |
| * is not supported by this set |
| */ |
| boolean remove(Object o); |
| |
| |
| // Bulk Operations |
| |
| /** |
| * Returns {@code true} if this set contains all of the elements of the |
| * specified collection. If the specified collection is also a set, this |
| * method returns {@code true} if it is a <i>subset</i> of this set. |
| * |
| * @param c collection to be checked for containment in this set |
| * @return {@code true} if this set contains all of the elements of the |
| * specified collection |
| * @throws ClassCastException if the types of one or more elements |
| * in the specified collection are incompatible with this |
| * set |
| * (<a href="Collection.html#optional-restrictions">optional</a>) |
| * @throws NullPointerException if the specified collection contains one |
| * or more null elements and this set does not permit null |
| * elements |
| * (<a href="Collection.html#optional-restrictions">optional</a>), |
| * or if the specified collection is null |
| * @see #contains(Object) |
| */ |
| boolean containsAll(Collection<?> c); |
| |
| /** |
| * Adds all of the elements in the specified collection to this set if |
| * they're not already present (optional operation). If the specified |
| * collection is also a set, the {@code addAll} operation effectively |
| * modifies this set so that its value is the <i>union</i> of the two |
| * sets. The behavior of this operation is undefined if the specified |
| * collection is modified while the operation is in progress. |
| * |
| * @param c collection containing elements to be added to this set |
| * @return {@code true} if this set changed as a result of the call |
| * |
| * @throws UnsupportedOperationException if the {@code addAll} operation |
| * is not supported by this set |
| * @throws ClassCastException if the class of an element of the |
| * specified collection prevents it from being added to this set |
| * @throws NullPointerException if the specified collection contains one |
| * or more null elements and this set does not permit null |
| * elements, or if the specified collection is null |
| * @throws IllegalArgumentException if some property of an element of the |
| * specified collection prevents it from being added to this set |
| * @see #add(Object) |
| */ |
| boolean addAll(Collection<? extends E> c); |
| |
| /** |
| * Retains only the elements in this set that are contained in the |
| * specified collection (optional operation). In other words, removes |
| * from this set all of its elements that are not contained in the |
| * specified collection. If the specified collection is also a set, this |
| * operation effectively modifies this set so that its value is the |
| * <i>intersection</i> of the two sets. |
| * |
| * @param c collection containing elements to be retained in this set |
| * @return {@code true} if this set changed as a result of the call |
| * @throws UnsupportedOperationException if the {@code retainAll} operation |
| * is not supported by this set |
| * @throws ClassCastException if the class of an element of this set |
| * is incompatible with the specified collection |
| * (<a href="Collection.html#optional-restrictions">optional</a>) |
| * @throws NullPointerException if this set contains a null element and the |
| * specified collection does not permit null elements |
| * (<a href="Collection.html#optional-restrictions">optional</a>), |
| * or if the specified collection is null |
| * @see #remove(Object) |
| */ |
| boolean retainAll(Collection<?> c); |
| |
| /** |
| * Removes from this set all of its elements that are contained in the |
| * specified collection (optional operation). If the specified |
| * collection is also a set, this operation effectively modifies this |
| * set so that its value is the <i>asymmetric set difference</i> of |
| * the two sets. |
| * |
| * @param c collection containing elements to be removed from this set |
| * @return {@code true} if this set changed as a result of the call |
| * @throws UnsupportedOperationException if the {@code removeAll} operation |
| * is not supported by this set |
| * @throws ClassCastException if the class of an element of this set |
| * is incompatible with the specified collection |
| * (<a href="Collection.html#optional-restrictions">optional</a>) |
| * @throws NullPointerException if this set contains a null element and the |
| * specified collection does not permit null elements |
| * (<a href="Collection.html#optional-restrictions">optional</a>), |
| * or if the specified collection is null |
| * @see #remove(Object) |
| * @see #contains(Object) |
| */ |
| boolean removeAll(Collection<?> c); |
| |
| /** |
| * Removes all of the elements from this set (optional operation). |
| * The set will be empty after this call returns. |
| * |
| * @throws UnsupportedOperationException if the {@code clear} method |
| * is not supported by this set |
| */ |
| void clear(); |
| |
| |
| // Comparison and hashing |
| |
| /** |
| * Compares the specified object with this set for equality. Returns |
| * {@code true} if the specified object is also a set, the two sets |
| * have the same size, and every member of the specified set is |
| * contained in this set (or equivalently, every member of this set is |
| * contained in the specified set). This definition ensures that the |
| * equals method works properly across different implementations of the |
| * set interface. |
| * |
| * @param o object to be compared for equality with this set |
| * @return {@code true} if the specified object is equal to this set |
| */ |
| boolean equals(Object o); |
| |
| /** |
| * Returns the hash code value for this set. The hash code of a set is |
| * defined to be the sum of the hash codes of the elements in the set, |
| * where the hash code of a {@code null} element is defined to be zero. |
| * This ensures that {@code s1.equals(s2)} implies that |
| * {@code s1.hashCode()==s2.hashCode()} for any two sets {@code s1} |
| * and {@code s2}, as required by the general contract of |
| * {@link Object#hashCode}. |
| * |
| * @return the hash code value for this set |
| * @see Object#equals(Object) |
| * @see Set#equals(Object) |
| */ |
| int hashCode(); |
| |
| /** |
| * Creates a {@code Spliterator} over the elements in this set. |
| * |
| * <p>The {@code Spliterator} reports {@link Spliterator#DISTINCT}. |
| * Implementations should document the reporting of additional |
| * characteristic values. |
| * |
| * @implSpec |
| * The default implementation creates a |
| * <em><a href="Spliterator.html#binding">late-binding</a></em> spliterator |
| * from the set's {@code Iterator}. The spliterator inherits the |
| * <em>fail-fast</em> properties of the set's iterator. |
| * <p> |
| * The created {@code Spliterator} additionally reports |
| * {@link Spliterator#SIZED}. |
| * |
| * @implNote |
| * The created {@code Spliterator} additionally reports |
| * {@link Spliterator#SUBSIZED}. |
| * |
| * @return a {@code Spliterator} over the elements in this set |
| * @since 1.8 |
| */ |
| @Override |
| default Spliterator<E> spliterator() { |
| return Spliterators.spliterator(this, Spliterator.DISTINCT); |
| } |
| |
| /** |
| * Returns an unmodifiable set containing zero elements. |
| * See <a href="#unmodifiable">Unmodifiable Sets</a> for details. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @return an empty {@code Set} |
| * |
| * @since 9 |
| */ |
| @SuppressWarnings("unchecked") |
| static <E> Set<E> of() { |
| return (Set<E>) ImmutableCollections.EMPTY_SET; |
| } |
| |
| /** |
| * Returns an unmodifiable set containing one element. |
| * See <a href="#unmodifiable">Unmodifiable Sets</a> for details. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @param e1 the single element |
| * @return a {@code Set} containing the specified element |
| * @throws NullPointerException if the element is {@code null} |
| * |
| * @since 9 |
| */ |
| static <E> Set<E> of(E e1) { |
| return new ImmutableCollections.Set12<>(e1); |
| } |
| |
| /** |
| * Returns an unmodifiable set containing two elements. |
| * See <a href="#unmodifiable">Unmodifiable Sets</a> for details. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @param e1 the first element |
| * @param e2 the second element |
| * @return a {@code Set} containing the specified elements |
| * @throws IllegalArgumentException if the elements are duplicates |
| * @throws NullPointerException if an element is {@code null} |
| * |
| * @since 9 |
| */ |
| static <E> Set<E> of(E e1, E e2) { |
| return new ImmutableCollections.Set12<>(e1, e2); |
| } |
| |
| /** |
| * Returns an unmodifiable set containing three elements. |
| * See <a href="#unmodifiable">Unmodifiable Sets</a> for details. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @param e1 the first element |
| * @param e2 the second element |
| * @param e3 the third element |
| * @return a {@code Set} containing the specified elements |
| * @throws IllegalArgumentException if there are any duplicate elements |
| * @throws NullPointerException if an element is {@code null} |
| * |
| * @since 9 |
| */ |
| static <E> Set<E> of(E e1, E e2, E e3) { |
| return new ImmutableCollections.SetN<>(e1, e2, e3); |
| } |
| |
| /** |
| * Returns an unmodifiable set containing four elements. |
| * See <a href="#unmodifiable">Unmodifiable Sets</a> for details. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @param e1 the first element |
| * @param e2 the second element |
| * @param e3 the third element |
| * @param e4 the fourth element |
| * @return a {@code Set} containing the specified elements |
| * @throws IllegalArgumentException if there are any duplicate elements |
| * @throws NullPointerException if an element is {@code null} |
| * |
| * @since 9 |
| */ |
| static <E> Set<E> of(E e1, E e2, E e3, E e4) { |
| return new ImmutableCollections.SetN<>(e1, e2, e3, e4); |
| } |
| |
| /** |
| * Returns an unmodifiable set containing five elements. |
| * See <a href="#unmodifiable">Unmodifiable Sets</a> for details. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @param e1 the first element |
| * @param e2 the second element |
| * @param e3 the third element |
| * @param e4 the fourth element |
| * @param e5 the fifth element |
| * @return a {@code Set} containing the specified elements |
| * @throws IllegalArgumentException if there are any duplicate elements |
| * @throws NullPointerException if an element is {@code null} |
| * |
| * @since 9 |
| */ |
| static <E> Set<E> of(E e1, E e2, E e3, E e4, E e5) { |
| return new ImmutableCollections.SetN<>(e1, e2, e3, e4, e5); |
| } |
| |
| /** |
| * Returns an unmodifiable set containing six elements. |
| * See <a href="#unmodifiable">Unmodifiable Sets</a> for details. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @param e1 the first element |
| * @param e2 the second element |
| * @param e3 the third element |
| * @param e4 the fourth element |
| * @param e5 the fifth element |
| * @param e6 the sixth element |
| * @return a {@code Set} containing the specified elements |
| * @throws IllegalArgumentException if there are any duplicate elements |
| * @throws NullPointerException if an element is {@code null} |
| * |
| * @since 9 |
| */ |
| static <E> Set<E> of(E e1, E e2, E e3, E e4, E e5, E e6) { |
| return new ImmutableCollections.SetN<>(e1, e2, e3, e4, e5, |
| e6); |
| } |
| |
| /** |
| * Returns an unmodifiable set containing seven elements. |
| * See <a href="#unmodifiable">Unmodifiable Sets</a> for details. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @param e1 the first element |
| * @param e2 the second element |
| * @param e3 the third element |
| * @param e4 the fourth element |
| * @param e5 the fifth element |
| * @param e6 the sixth element |
| * @param e7 the seventh element |
| * @return a {@code Set} containing the specified elements |
| * @throws IllegalArgumentException if there are any duplicate elements |
| * @throws NullPointerException if an element is {@code null} |
| * |
| * @since 9 |
| */ |
| static <E> Set<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E e7) { |
| return new ImmutableCollections.SetN<>(e1, e2, e3, e4, e5, |
| e6, e7); |
| } |
| |
| /** |
| * Returns an unmodifiable set containing eight elements. |
| * See <a href="#unmodifiable">Unmodifiable Sets</a> for details. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @param e1 the first element |
| * @param e2 the second element |
| * @param e3 the third element |
| * @param e4 the fourth element |
| * @param e5 the fifth element |
| * @param e6 the sixth element |
| * @param e7 the seventh element |
| * @param e8 the eighth element |
| * @return a {@code Set} containing the specified elements |
| * @throws IllegalArgumentException if there are any duplicate elements |
| * @throws NullPointerException if an element is {@code null} |
| * |
| * @since 9 |
| */ |
| static <E> Set<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8) { |
| return new ImmutableCollections.SetN<>(e1, e2, e3, e4, e5, |
| e6, e7, e8); |
| } |
| |
| /** |
| * Returns an unmodifiable set containing nine elements. |
| * See <a href="#unmodifiable">Unmodifiable Sets</a> for details. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @param e1 the first element |
| * @param e2 the second element |
| * @param e3 the third element |
| * @param e4 the fourth element |
| * @param e5 the fifth element |
| * @param e6 the sixth element |
| * @param e7 the seventh element |
| * @param e8 the eighth element |
| * @param e9 the ninth element |
| * @return a {@code Set} containing the specified elements |
| * @throws IllegalArgumentException if there are any duplicate elements |
| * @throws NullPointerException if an element is {@code null} |
| * |
| * @since 9 |
| */ |
| static <E> Set<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9) { |
| return new ImmutableCollections.SetN<>(e1, e2, e3, e4, e5, |
| e6, e7, e8, e9); |
| } |
| |
| /** |
| * Returns an unmodifiable set containing ten elements. |
| * See <a href="#unmodifiable">Unmodifiable Sets</a> for details. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @param e1 the first element |
| * @param e2 the second element |
| * @param e3 the third element |
| * @param e4 the fourth element |
| * @param e5 the fifth element |
| * @param e6 the sixth element |
| * @param e7 the seventh element |
| * @param e8 the eighth element |
| * @param e9 the ninth element |
| * @param e10 the tenth element |
| * @return a {@code Set} containing the specified elements |
| * @throws IllegalArgumentException if there are any duplicate elements |
| * @throws NullPointerException if an element is {@code null} |
| * |
| * @since 9 |
| */ |
| static <E> Set<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9, E e10) { |
| return new ImmutableCollections.SetN<>(e1, e2, e3, e4, e5, |
| e6, e7, e8, e9, e10); |
| } |
| |
| /** |
| * Returns an unmodifiable set containing an arbitrary number of elements. |
| * See <a href="#unmodifiable">Unmodifiable Sets</a> for details. |
| * |
| * @apiNote |
| * This method also accepts a single array as an argument. The element type of |
| * the resulting set will be the component type of the array, and the size of |
| * the set will be equal to the length of the array. To create a set with |
| * a single element that is an array, do the following: |
| * |
| * <pre>{@code |
| * String[] array = ... ; |
| * Set<String[]> list = Set.<String[]>of(array); |
| * }</pre> |
| * |
| * This will cause the {@link Set#of(Object) Set.of(E)} method |
| * to be invoked instead. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @param elements the elements to be contained in the set |
| * @return a {@code Set} containing the specified elements |
| * @throws IllegalArgumentException if there are any duplicate elements |
| * @throws NullPointerException if an element is {@code null} or if the array is {@code null} |
| * |
| * @since 9 |
| */ |
| @SafeVarargs |
| @SuppressWarnings("varargs") |
| static <E> Set<E> of(E... elements) { |
| switch (elements.length) { // implicit null check of elements |
| case 0: |
| @SuppressWarnings("unchecked") |
| var set = (Set<E>) ImmutableCollections.EMPTY_SET; |
| return set; |
| case 1: |
| return new ImmutableCollections.Set12<>(elements[0]); |
| case 2: |
| return new ImmutableCollections.Set12<>(elements[0], elements[1]); |
| default: |
| return new ImmutableCollections.SetN<>(elements); |
| } |
| } |
| |
| /** |
| * Returns an <a href="#unmodifiable">unmodifiable Set</a> containing the elements |
| * of the given Collection. The given Collection must not be null, and it must not |
| * contain any null elements. If the given Collection contains duplicate elements, |
| * an arbitrary element of the duplicates is preserved. If the given Collection is |
| * subsequently modified, the returned Set will not reflect such modifications. |
| * |
| * @implNote |
| * If the given Collection is an <a href="#unmodifiable">unmodifiable Set</a>, |
| * calling copyOf will generally not create a copy. |
| * |
| * @param <E> the {@code Set}'s element type |
| * @param coll a {@code Collection} from which elements are drawn, must be non-null |
| * @return a {@code Set} containing the elements of the given {@code Collection} |
| * @throws NullPointerException if coll is null, or if it contains any nulls |
| * @since 10 |
| */ |
| @SuppressWarnings("unchecked") |
| static <E> Set<E> copyOf(Collection<? extends E> coll) { |
| if (coll instanceof ImmutableCollections.AbstractImmutableSet) { |
| return (Set<E>)coll; |
| } else { |
| return (Set<E>)Set.of(new HashSet<>(coll).toArray()); |
| } |
| } |
| } |
