/* * Copyright (c) 1997, 2017, 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; import java.util.function.UnaryOperator; /** * An ordered collection (also known as a sequence). The user of this * interface has precise control over where in the list each element is * inserted. The user can access elements by their integer index (position in * the list), and search for elements in the list.

* * Unlike sets, lists typically allow duplicate elements. More formally, * lists typically allow pairs of elements {@code e1} and {@code e2} * such that {@code e1.equals(e2)}, and they typically allow multiple * null elements if they allow null elements at all. It is not inconceivable * that someone might wish to implement a list that prohibits duplicates, by * throwing runtime exceptions when the user attempts to insert them, but we * expect this usage to be rare.

* * The {@code List} interface places additional stipulations, beyond those * specified in the {@code Collection} interface, on the contracts of the * {@code iterator}, {@code add}, {@code remove}, {@code equals}, and * {@code hashCode} methods. Declarations for other inherited methods are * also included here for convenience.

* * The {@code List} interface provides four methods for positional (indexed) * access to list elements. Lists (like Java arrays) are zero based. Note * that these operations may execute in time proportional to the index value * for some implementations (the {@code LinkedList} class, for * example). Thus, iterating over the elements in a list is typically * preferable to indexing through it if the caller does not know the * implementation.

* * The {@code List} interface provides a special iterator, called a * {@code ListIterator}, that allows element insertion and replacement, and * bidirectional access in addition to the normal operations that the * {@code Iterator} interface provides. A method is provided to obtain a * list iterator that starts at a specified position in the list.

* * The {@code List} interface provides two methods to search for a specified * object. From a performance standpoint, these methods should be used with * caution. In many implementations they will perform costly linear * searches.

* * The {@code List} interface provides two methods to efficiently insert and * remove multiple elements at an arbitrary point in the list.

* * Note: While it is permissible for lists to contain themselves as elements, * extreme caution is advised: the {@code equals} and {@code hashCode} * methods are no longer well defined on such a list. * *

Some list 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 list 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. * *

Unmodifiable Lists

*

The {@link List#of(Object...) List.of} and * {@link List#copyOf List.copyOf} static factory methods * provide a convenient way to create unmodifiable lists. The {@code List} * instances created by these methods have the following characteristics: * *

* *

This interface is a member of the * * Java Collections Framework. * * @param the type of elements in this list * * @author Josh Bloch * @author Neal Gafter * @see Collection * @see Set * @see ArrayList * @see LinkedList * @see Vector * @see Arrays#asList(Object[]) * @see Collections#nCopies(int, Object) * @see Collections#EMPTY_LIST * @see AbstractList * @see AbstractSequentialList * @since 1.2 */ public interface List extends Collection { // Query Operations /** * Returns the number of elements in this list. If this list contains * more than {@code Integer.MAX_VALUE} elements, returns * {@code Integer.MAX_VALUE}. * * @return the number of elements in this list */ int size(); /** * Returns {@code true} if this list contains no elements. * * @return {@code true} if this list contains no elements */ boolean isEmpty(); /** * Returns {@code true} if this list contains the specified element. * More formally, returns {@code true} if and only if this list contains * at least one element {@code e} such that * {@code Objects.equals(o, e)}. * * @param o element whose presence in this list is to be tested * @return {@code true} if this list contains the specified element * @throws ClassCastException if the type of the specified element * is incompatible with this list * (optional) * @throws NullPointerException if the specified element is null and this * list does not permit null elements * (optional) */ boolean contains(Object o); /** * Returns an iterator over the elements in this list in proper sequence. * * @return an iterator over the elements in this list in proper sequence */ Iterator iterator(); /** * Returns an array containing all of the elements in this list in proper * sequence (from first to last element). * *

The returned array will be "safe" in that no references to it are * maintained by this list. (In other words, this method must * allocate a new array even if this list is backed by an array). * The caller is thus free to modify the returned array. * *

This method acts as bridge between array-based and collection-based * APIs. * * @return an array containing all of the elements in this list in proper * sequence * @see Arrays#asList(Object[]) */ Object[] toArray(); /** * Returns an array containing all of the elements in this list in * proper sequence (from first to last element); the runtime type of * the returned array is that of the specified array. If the list 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 list. * *

If the list fits in the specified array with room to spare (i.e., * the array has more elements than the list), the element in the array * immediately following the end of the list is set to {@code null}. * (This is useful in determining the length of the list only if * the caller knows that the list does not contain any null elements.) * *

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. * *

Suppose {@code x} is a list known to contain only strings. * The following code can be used to dump the list into a newly * allocated array of {@code String}: * * 

{@code
     *     String[] y = x.toArray(new String[0]);
     * }
* * Note that {@code toArray(new Object[0])} is identical in function to * {@code toArray()}. * * @param a the array into which the elements of this list 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 the elements of this list * @throws ArrayStoreException if the runtime type of the specified array * is not a supertype of the runtime type of every element in * this list * @throws NullPointerException if the specified array is null */ T[] toArray(T[] a); // Modification Operations /** * Appends the specified element to the end of this list (optional * operation). * *

Lists that support this operation may place limitations on what * elements may be added to this list. In particular, some * lists will refuse to add null elements, and others will impose * restrictions on the type of elements that may be added. List * classes should clearly specify in their documentation any restrictions * on what elements may be added. * * @param e element to be appended to this list * @return {@code true} (as specified by {@link Collection#add}) * @throws UnsupportedOperationException if the {@code add} operation * is not supported by this list * @throws ClassCastException if the class of the specified element * prevents it from being added to this list * @throws NullPointerException if the specified element is null and this * list does not permit null elements * @throws IllegalArgumentException if some property of this element * prevents it from being added to this list */ boolean add(E e); /** * Removes the first occurrence of the specified element from this list, * if it is present (optional operation). If this list does not contain * the element, it is unchanged. More formally, removes the element with * the lowest index {@code i} such that * {@code Objects.equals(o, get(i))} * (if such an element exists). Returns {@code true} if this list * contained the specified element (or equivalently, if this list changed * as a result of the call). * * @param o element to be removed from this list, if present * @return {@code true} if this list contained the specified element * @throws ClassCastException if the type of the specified element * is incompatible with this list * (optional) * @throws NullPointerException if the specified element is null and this * list does not permit null elements * (optional) * @throws UnsupportedOperationException if the {@code remove} operation * is not supported by this list */ boolean remove(Object o); // Bulk Modification Operations /** * Returns {@code true} if this list contains all of the elements of the * specified collection. * * @param c collection to be checked for containment in this list * @return {@code true} if this list 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 * list * (optional) * @throws NullPointerException if the specified collection contains one * or more null elements and this list does not permit null * elements * (optional), * or if the specified collection is null * @see #contains(Object) */ boolean containsAll(Collection c); /** * Appends all of the elements in the specified collection to the end of * this list, in the order that they are returned by the specified * collection's iterator (optional operation). The behavior of this * operation is undefined if the specified collection is modified while * the operation is in progress. (Note that this will occur if the * specified collection is this list, and it's nonempty.) * * @param c collection containing elements to be added to this list * @return {@code true} if this list changed as a result of the call * @throws UnsupportedOperationException if the {@code addAll} operation * is not supported by this list * @throws ClassCastException if the class of an element of the specified * collection prevents it from being added to this list * @throws NullPointerException if the specified collection contains one * or more null elements and this list 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 list * @see #add(Object) */ boolean addAll(Collection c); /** * Inserts all of the elements in the specified collection into this * list at the specified position (optional operation). Shifts the * element currently at that position (if any) and any subsequent * elements to the right (increases their indices). The new elements * will appear in this list in the order that they are returned by the * specified collection's iterator. The behavior of this operation is * undefined if the specified collection is modified while the * operation is in progress. (Note that this will occur if the specified * collection is this list, and it's nonempty.) * * @param index index at which to insert the first element from the * specified collection * @param c collection containing elements to be added to this list * @return {@code true} if this list changed as a result of the call * @throws UnsupportedOperationException if the {@code addAll} operation * is not supported by this list * @throws ClassCastException if the class of an element of the specified * collection prevents it from being added to this list * @throws NullPointerException if the specified collection contains one * or more null elements and this list 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 list * @throws IndexOutOfBoundsException if the index is out of range * ({@code index < 0 || index > size()}) */ boolean addAll(int index, Collection c); /** * Removes from this list all of its elements that are contained in the * specified collection (optional operation). * * @param c collection containing elements to be removed from this list * @return {@code true} if this list changed as a result of the call * @throws UnsupportedOperationException if the {@code removeAll} operation * is not supported by this list * @throws ClassCastException if the class of an element of this list * is incompatible with the specified collection * (optional) * @throws NullPointerException if this list contains a null element and the * specified collection does not permit null elements * (optional), * or if the specified collection is null * @see #remove(Object) * @see #contains(Object) */ boolean removeAll(Collection c); /** * Retains only the elements in this list that are contained in the * specified collection (optional operation). In other words, removes * from this list all of its elements that are not contained in the * specified collection. * * @param c collection containing elements to be retained in this list * @return {@code true} if this list changed as a result of the call * @throws UnsupportedOperationException if the {@code retainAll} operation * is not supported by this list * @throws ClassCastException if the class of an element of this list * is incompatible with the specified collection * (optional) * @throws NullPointerException if this list contains a null element and the * specified collection does not permit null elements * (optional), * or if the specified collection is null * @see #remove(Object) * @see #contains(Object) */ boolean retainAll(Collection c); /** * Replaces each element of this list with the result of applying the * operator to that element. Errors or runtime exceptions thrown by * the operator are relayed to the caller. * * @implSpec * The default implementation is equivalent to, for this {@code list}: * 

{@code
     *     final ListIterator li = list.listIterator();
     *     while (li.hasNext()) {
     *         li.set(operator.apply(li.next()));
     *     }
     * }
* * If the list's list-iterator does not support the {@code set} operation * then an {@code UnsupportedOperationException} will be thrown when * replacing the first element. * * @param operator the operator to apply to each element * @throws UnsupportedOperationException if this list is unmodifiable. * Implementations may throw this exception if an element * cannot be replaced or if, in general, modification is not * supported * @throws NullPointerException if the specified operator is null or * if the operator result is a null value and this list does * not permit null elements * (optional) * @since 1.8 */ default void replaceAll(UnaryOperator operator) { Objects.requireNonNull(operator); final ListIterator li = this.listIterator(); while (li.hasNext()) { li.set(operator.apply(li.next())); } } /** * Sorts this list according to the order induced by the specified * {@link Comparator}. The sort is stable: this method must not * reorder equal elements. * *

All elements in this list must be mutually comparable using the * specified comparator (that is, {@code c.compare(e1, e2)} must not throw * a {@code ClassCastException} for any elements {@code e1} and {@code e2} * in the list). * *

If the specified comparator is {@code null} then all elements in this * list must implement the {@link Comparable} interface and the elements' * {@linkplain Comparable natural ordering} should be used. * *

This list must be modifiable, but need not be resizable. * * @implSpec * The default implementation obtains an array containing all elements in * this list, sorts the array, and iterates over this list resetting each * element from the corresponding position in the array. (This avoids the * n2 log(n) performance that would result from attempting * to sort a linked list in place.) * * @implNote * This implementation is a stable, adaptive, iterative mergesort that * requires far fewer than n lg(n) comparisons when the input array is * partially sorted, while offering the performance of a traditional * mergesort when the input array is randomly ordered. If the input array * is nearly sorted, the implementation requires approximately n * comparisons. Temporary storage requirements vary from a small constant * for nearly sorted input arrays to n/2 object references for randomly * ordered input arrays. * *

The implementation takes equal advantage of ascending and * descending order in its input array, and can take advantage of * ascending and descending order in different parts of the same * input array. It is well-suited to merging two or more sorted arrays: * simply concatenate the arrays and sort the resulting array. * *

The implementation was adapted from Tim Peters's list sort for Python * ( * TimSort). It uses techniques from Peter McIlroy's "Optimistic * Sorting and Information Theoretic Complexity", in Proceedings of the * Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, pp 467-474, * January 1993. * * @param c the {@code Comparator} used to compare list elements. * A {@code null} value indicates that the elements' * {@linkplain Comparable natural ordering} should be used * @throws ClassCastException if the list contains elements that are not * mutually comparable using the specified comparator * @throws UnsupportedOperationException if the list's list-iterator does * not support the {@code set} operation * @throws IllegalArgumentException * (optional) * if the comparator is found to violate the {@link Comparator} * contract * @since 1.8 */ @SuppressWarnings({"unchecked", "rawtypes"}) default void sort(Comparator c) { Object[] a = this.toArray(); Arrays.sort(a, (Comparator) c); ListIterator i = this.listIterator(); for (Object e : a) { i.next(); i.set((E) e); } } /** * Removes all of the elements from this list (optional operation). * The list will be empty after this call returns. * * @throws UnsupportedOperationException if the {@code clear} operation * is not supported by this list */ void clear(); // Comparison and hashing /** * Compares the specified object with this list for equality. Returns * {@code true} if and only if the specified object is also a list, both * lists have the same size, and all corresponding pairs of elements in * the two lists are equal. (Two elements {@code e1} and * {@code e2} are equal if {@code Objects.equals(e1, e2)}.) * In other words, two lists are defined to be * equal if they contain the same elements in the same order. This * definition ensures that the equals method works properly across * different implementations of the {@code List} interface. * * @param o the object to be compared for equality with this list * @return {@code true} if the specified object is equal to this list */ boolean equals(Object o); /** * Returns the hash code value for this list. The hash code of a list * is defined to be the result of the following calculation: * 

{@code
     *     int hashCode = 1;
     *     for (E e : list)
     *         hashCode = 31*hashCode + (e==null ? 0 : e.hashCode());
     * }
* This ensures that {@code list1.equals(list2)} implies that * {@code list1.hashCode()==list2.hashCode()} for any two lists, * {@code list1} and {@code list2}, as required by the general * contract of {@link Object#hashCode}. * * @return the hash code value for this list * @see Object#equals(Object) * @see #equals(Object) */ int hashCode(); // Positional Access Operations /** * Returns the element at the specified position in this list. * * @param index index of the element to return * @return the element at the specified position in this list * @throws IndexOutOfBoundsException if the index is out of range * ({@code index < 0 || index >= size()}) */ E get(int index); /** * Replaces the element at the specified position in this list with the * specified element (optional operation). * * @param index index of the element to replace * @param element element to be stored at the specified position * @return the element previously at the specified position * @throws UnsupportedOperationException if the {@code set} operation * is not supported by this list * @throws ClassCastException if the class of the specified element * prevents it from being added to this list * @throws NullPointerException if the specified element is null and * this list does not permit null elements * @throws IllegalArgumentException if some property of the specified * element prevents it from being added to this list * @throws IndexOutOfBoundsException if the index is out of range * ({@code index < 0 || index >= size()}) */ E set(int index, E element); /** * Inserts the specified element at the specified position in this list * (optional operation). Shifts the element currently at that position * (if any) and any subsequent elements to the right (adds one to their * indices). * * @param index index at which the specified element is to be inserted * @param element element to be inserted * @throws UnsupportedOperationException if the {@code add} operation * is not supported by this list * @throws ClassCastException if the class of the specified element * prevents it from being added to this list * @throws NullPointerException if the specified element is null and * this list does not permit null elements * @throws IllegalArgumentException if some property of the specified * element prevents it from being added to this list * @throws IndexOutOfBoundsException if the index is out of range * ({@code index < 0 || index > size()}) */ void add(int index, E element); /** * Removes the element at the specified position in this list (optional * operation). Shifts any subsequent elements to the left (subtracts one * from their indices). Returns the element that was removed from the * list. * * @param index the index of the element to be removed * @return the element previously at the specified position * @throws UnsupportedOperationException if the {@code remove} operation * is not supported by this list * @throws IndexOutOfBoundsException if the index is out of range * ({@code index < 0 || index >= size()}) */ E remove(int index); // Search Operations /** * Returns the index of the first occurrence of the specified element * in this list, or -1 if this list does not contain the element. * More formally, returns the lowest index {@code i} such that * {@code Objects.equals(o, get(i))}, * or -1 if there is no such index. * * @param o element to search for * @return the index of the first occurrence of the specified element in * this list, or -1 if this list does not contain the element * @throws ClassCastException if the type of the specified element * is incompatible with this list * (optional) * @throws NullPointerException if the specified element is null and this * list does not permit null elements * (optional) */ int indexOf(Object o); /** * Returns the index of the last occurrence of the specified element * in this list, or -1 if this list does not contain the element. * More formally, returns the highest index {@code i} such that * {@code Objects.equals(o, get(i))}, * or -1 if there is no such index. * * @param o element to search for * @return the index of the last occurrence of the specified element in * this list, or -1 if this list does not contain the element * @throws ClassCastException if the type of the specified element * is incompatible with this list * (optional) * @throws NullPointerException if the specified element is null and this * list does not permit null elements * (optional) */ int lastIndexOf(Object o); // List Iterators /** * Returns a list iterator over the elements in this list (in proper * sequence). * * @return a list iterator over the elements in this list (in proper * sequence) */ ListIterator listIterator(); /** * Returns a list iterator over the elements in this list (in proper * sequence), starting at the specified position in the list. * The specified index indicates the first element that would be * returned by an initial call to {@link ListIterator#next next}. * An initial call to {@link ListIterator#previous previous} would * return the element with the specified index minus one. * * @param index index of the first element to be returned from the * list iterator (by a call to {@link ListIterator#next next}) * @return a list iterator over the elements in this list (in proper * sequence), starting at the specified position in the list * @throws IndexOutOfBoundsException if the index is out of range * ({@code index < 0 || index > size()}) */ ListIterator listIterator(int index); // View /** * Returns a view of the portion of this list between the specified * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. (If * {@code fromIndex} and {@code toIndex} are equal, the returned list is * empty.) The returned list is backed by this list, so non-structural * changes in the returned list are reflected in this list, and vice-versa. * The returned list supports all of the optional list operations supported * by this list.

* * This method eliminates the need for explicit range operations (of * the sort that commonly exist for arrays). Any operation that expects * a list can be used as a range operation by passing a subList view * instead of a whole list. For example, the following idiom * removes a range of elements from a list: * 

{@code
     *      list.subList(from, to).clear();
     * }
* Similar idioms may be constructed for {@code indexOf} and * {@code lastIndexOf}, and all of the algorithms in the * {@code Collections} class can be applied to a subList.

* * The semantics of the list returned by this method become undefined if * the backing list (i.e., this list) is structurally modified in * any way other than via the returned list. (Structural modifications are * those that change the size of this list, or otherwise perturb it in such * a fashion that iterations in progress may yield incorrect results.) * * @param fromIndex low endpoint (inclusive) of the subList * @param toIndex high endpoint (exclusive) of the subList * @return a view of the specified range within this list * @throws IndexOutOfBoundsException for an illegal endpoint index value * ({@code fromIndex < 0 || toIndex > size || * fromIndex > toIndex}) */ List subList(int fromIndex, int toIndex); /** * Creates a {@link Spliterator} over the elements in this list. * *

The {@code Spliterator} reports {@link Spliterator#SIZED} and * {@link Spliterator#ORDERED}. Implementations should document the * reporting of additional characteristic values. * * @implSpec * The default implementation creates a * late-binding * spliterator as follows: *

    *
  • If the list is an instance of {@link RandomAccess} then the default * implementation creates a spliterator that traverses elements by * invoking the method {@link List#get}. If such invocation results or * would result in an {@code IndexOutOfBoundsException} then the * spliterator will fail-fast and throw a * {@code ConcurrentModificationException}. * If the list is also an instance of {@link AbstractList} then the * spliterator will use the list's {@link AbstractList#modCount modCount} * field to provide additional fail-fast behavior. *
  • Otherwise, the default implementation creates a spliterator from the * list's {@code Iterator}. The spliterator inherits the * fail-fast of the list's iterator. *
* * @implNote * The created {@code Spliterator} additionally reports * {@link Spliterator#SUBSIZED}. * * @return a {@code Spliterator} over the elements in this list * @since 1.8 */ @Override default Spliterator spliterator() { if (this instanceof RandomAccess) { return new AbstractList.RandomAccessSpliterator<>(this); } else { return Spliterators.spliterator(this, Spliterator.ORDERED); } } /** * Returns an unmodifiable list containing zero elements. * * See Unmodifiable Lists for details. * * @param the {@code List}'s element type * @return an empty {@code List} * * @since 9 */ static List of() { return ImmutableCollections.emptyList(); } /** * Returns an unmodifiable list containing one element. * * See Unmodifiable Lists for details. * * @param the {@code List}'s element type * @param e1 the single element * @return a {@code List} containing the specified element * @throws NullPointerException if the element is {@code null} * * @since 9 */ static List of(E e1) { return new ImmutableCollections.List12<>(e1); } /** * Returns an unmodifiable list containing two elements. * * See Unmodifiable Lists for details. * * @param the {@code List}'s element type * @param e1 the first element * @param e2 the second element * @return a {@code List} containing the specified elements * @throws NullPointerException if an element is {@code null} * * @since 9 */ static List of(E e1, E e2) { return new ImmutableCollections.List12<>(e1, e2); } /** * Returns an unmodifiable list containing three elements. * * See Unmodifiable Lists for details. * * @param the {@code List}'s element type * @param e1 the first element * @param e2 the second element * @param e3 the third element * @return a {@code List} containing the specified elements * @throws NullPointerException if an element is {@code null} * * @since 9 */ static List of(E e1, E e2, E e3) { return new ImmutableCollections.ListN<>(e1, e2, e3); } /** * Returns an unmodifiable list containing four elements. * * See Unmodifiable Lists for details. * * @param the {@code List}'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 List} containing the specified elements * @throws NullPointerException if an element is {@code null} * * @since 9 */ static List of(E e1, E e2, E e3, E e4) { return new ImmutableCollections.ListN<>(e1, e2, e3, e4); } /** * Returns an unmodifiable list containing five elements. * * See Unmodifiable Lists for details. * * @param the {@code List}'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 List} containing the specified elements * @throws NullPointerException if an element is {@code null} * * @since 9 */ static List of(E e1, E e2, E e3, E e4, E e5) { return new ImmutableCollections.ListN<>(e1, e2, e3, e4, e5); } /** * Returns an unmodifiable list containing six elements. * * See Unmodifiable Lists for details. * * @param the {@code List}'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 List} containing the specified elements * @throws NullPointerException if an element is {@code null} * * @since 9 */ static List of(E e1, E e2, E e3, E e4, E e5, E e6) { return new ImmutableCollections.ListN<>(e1, e2, e3, e4, e5, e6); } /** * Returns an unmodifiable list containing seven elements. * * See Unmodifiable Lists for details. * * @param the {@code List}'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 List} containing the specified elements * @throws NullPointerException if an element is {@code null} * * @since 9 */ static List of(E e1, E e2, E e3, E e4, E e5, E e6, E e7) { return new ImmutableCollections.ListN<>(e1, e2, e3, e4, e5, e6, e7); } /** * Returns an unmodifiable list containing eight elements. * * See Unmodifiable Lists for details. * * @param the {@code List}'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 List} containing the specified elements * @throws NullPointerException if an element is {@code null} * * @since 9 */ static List of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8) { return new ImmutableCollections.ListN<>(e1, e2, e3, e4, e5, e6, e7, e8); } /** * Returns an unmodifiable list containing nine elements. * * See Unmodifiable Lists for details. * * @param the {@code List}'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 List} containing the specified elements * @throws NullPointerException if an element is {@code null} * * @since 9 */ static List of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9) { return new ImmutableCollections.ListN<>(e1, e2, e3, e4, e5, e6, e7, e8, e9); } /** * Returns an unmodifiable list containing ten elements. * * See Unmodifiable Lists for details. * * @param the {@code List}'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 List} containing the specified elements * @throws NullPointerException if an element is {@code null} * * @since 9 */ static List of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9, E e10) { return new ImmutableCollections.ListN<>(e1, e2, e3, e4, e5, e6, e7, e8, e9, e10); } /** * Returns an unmodifiable list containing an arbitrary number of elements. * See Unmodifiable Lists for details. * * @apiNote * This method also accepts a single array as an argument. The element type of * the resulting list will be the component type of the array, and the size of * the list will be equal to the length of the array. To create a list with * a single element that is an array, do the following: * * 
{@code
     *     String[] array = ... ;
     *     List list = List.of(array);
     * }
* * This will cause the {@link List#of(Object) List.of(E)} method * to be invoked instead. * * @param the {@code List}'s element type * @param elements the elements to be contained in the list * @return a {@code List} containing the specified elements * @throws NullPointerException if an element is {@code null} or if the array is {@code null} * * @since 9 */ @SafeVarargs @SuppressWarnings("varargs") static List of(E... elements) { switch (elements.length) { // implicit null check of elements case 0: return ImmutableCollections.emptyList(); case 1: return new ImmutableCollections.List12<>(elements[0]); case 2: return new ImmutableCollections.List12<>(elements[0], elements[1]); default: return new ImmutableCollections.ListN<>(elements); } } /** * Returns an unmodifiable List containing the elements of * the given Collection, in its iteration order. The given Collection must not be null, * and it must not contain any null elements. If the given Collection is subsequently * modified, the returned List will not reflect such modifications. * * @implNote * If the given Collection is an unmodifiable List, * calling copyOf will generally not create a copy. * * @param the {@code List}'s element type * @param coll a {@code Collection} from which elements are drawn, must be non-null * @return a {@code List} 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 List copyOf(Collection coll) { if (coll instanceof ImmutableCollections.AbstractImmutableList) { return (List)coll; } else { return (List)List.of(coll.toArray()); } } }