| /* Set.java -- A collection that prohibits duplicates | |
| Copyright (C) 1998, 2001, 2005 Free Software Foundation, Inc. | |
| This file is part of GNU Classpath. | |
| GNU Classpath is free software; you can redistribute it and/or modify | |
| it under the terms of the GNU General Public License as published by | |
| the Free Software Foundation; either version 2, or (at your option) | |
| any later version. | |
| GNU Classpath 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 for more details. | |
| You should have received a copy of the GNU General Public License | |
| along with GNU Classpath; see the file COPYING. If not, write to the | |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA | |
| 02110-1301 USA. | |
| Linking this library statically or dynamically with other modules is | |
| making a combined work based on this library. Thus, the terms and | |
| conditions of the GNU General Public License cover the whole | |
| combination. | |
| As a special exception, the copyright holders of this library give you | |
| permission to link this library with independent modules to produce an | |
| executable, regardless of the license terms of these independent | |
| modules, and to copy and distribute the resulting executable under | |
| terms of your choice, provided that you also meet, for each linked | |
| independent module, the terms and conditions of the license of that | |
| module. An independent module is a module which is not derived from | |
| or based on this library. If you modify this library, you may extend | |
| this exception to your version of the library, but you are not | |
| obligated to do so. If you do not wish to do so, delete this | |
| exception statement from your version. */ | |
| package java.util; | |
| /** | |
| * A collection that contains no duplicates. In other words, for two set | |
| * elements e1 and e2, <code>e1.equals(e2)</code> returns false. There | |
| * are additional stipulations on <code>add</code>, <code>equals</code> | |
| * and <code>hashCode</code>, as well as the requirements that constructors | |
| * do not permit duplicate elements. The Set interface is incompatible with | |
| * List; you cannot implement both simultaneously. | |
| * <p> | |
| * | |
| * Note: Be careful about using mutable objects in sets. In particular, | |
| * if a mutable object changes to become equal to another set element, you | |
| * have violated the contract. As a special case of this, a Set is not | |
| * allowed to be an element of itself, without risking undefined behavior. | |
| * | |
| * @author Original author unknown | |
| * @author Eric Blake (ebb9@email.byu.edu) | |
| * @see Collection | |
| * @see List | |
| * @see SortedSet | |
| * @see HashSet | |
| * @see TreeSet | |
| * @see LinkedHashSet | |
| * @see AbstractSet | |
| * @see Collections#singleton(Object) | |
| * @see Collections#EMPTY_SET | |
| * @since 1.2 | |
| * @status updated to 1.4 | |
| */ | |
| public interface Set extends Collection | |
| { | |
| /** | |
| * Adds the specified element to the set if it is not already present | |
| * (optional operation). In particular, the comparison algorithm is | |
| * <code>o == null ? e == null : o.equals(e)</code>. Sets need not permit | |
| * all values, and may document what exceptions will be thrown if | |
| * a value is not permitted. | |
| * | |
| * @param o the object to add | |
| * @return true if the object was not previously in the set | |
| * @throws UnsupportedOperationException if this operation is not allowed | |
| * @throws ClassCastException if the class of o prevents it from being added | |
| * @throws IllegalArgumentException if some aspect of o prevents it from | |
| * being added | |
| * @throws NullPointerException if null is not permitted in this set | |
| */ | |
| boolean add(Object o); | |
| /** | |
| * Adds all of the elements of the given collection to this set (optional | |
| * operation). If the argument is also a Set, this returns the mathematical | |
| * <i>union</i> of the two. The behavior is unspecified if the set is | |
| * modified while this is taking place. | |
| * | |
| * @param c the collection to add | |
| * @return true if the set changed as a result | |
| * @throws UnsupportedOperationException if this operation is not allowed | |
| * @throws ClassCastException if the class of an element prevents it from | |
| * being added | |
| * @throws IllegalArgumentException if something about an element prevents | |
| * it from being added | |
| * @throws NullPointerException if null is not permitted in this set, or | |
| * if the argument c is null | |
| * @see #add(Object) | |
| */ | |
| boolean addAll(Collection c); | |
| /** | |
| * Removes all elements from this set (optional operation). This set will | |
| * be empty afterwords, unless an exception occurs. | |
| * | |
| * @throws UnsupportedOperationException if this operation is not allowed | |
| */ | |
| void clear(); | |
| /** | |
| * Returns true if the set contains the specified element. In other words, | |
| * this looks for <code>o == null ? e == null : o.equals(e)</code>. | |
| * | |
| * @param o the object to look for | |
| * @return true if it is found in the set | |
| * @throws ClassCastException if the type of o is not a valid type | |
| * for this set. | |
| * @throws NullPointerException if o is null and this set doesn't | |
| * support null values. | |
| */ | |
| boolean contains(Object o); | |
| /** | |
| * Returns true if this set contains all elements in the specified | |
| * collection. If the argument is also a set, this is the <i>subset</i> | |
| * relationship. | |
| * | |
| * @param c the collection to check membership in | |
| * @return true if all elements in this set are in c | |
| * @throws NullPointerException if c is null | |
| * @throws ClassCastException if the type of any element in c is not | |
| * a valid type for this set. | |
| * @throws NullPointerException if some element of c is null and this | |
| * set doesn't support null values. | |
| * @see #contains(Object) | |
| */ | |
| boolean containsAll(Collection c); | |
| /** | |
| * Compares the specified object to this for equality. For sets, the object | |
| * must be a set, the two must have the same size, and every element in | |
| * one must be in the other. | |
| * | |
| * @param o the object to compare to | |
| * @return true if it is an equal set | |
| */ | |
| boolean equals(Object o); | |
| /** | |
| * Returns the hash code for this set. In order to satisfy the contract of | |
| * equals, this is the sum of the hashcode of all elements in the set. | |
| * | |
| * @return the sum of the hashcodes of all set elements | |
| * @see #equals(Object) | |
| */ | |
| int hashCode(); | |
| /** | |
| * Returns true if the set contains no elements. | |
| * | |
| * @return true if the set is empty | |
| */ | |
| boolean isEmpty(); | |
| /** | |
| * Returns an iterator over the set. The iterator has no specific order, | |
| * unless further specified. | |
| * | |
| * @return a set iterator | |
| */ | |
| Iterator iterator(); | |
| /** | |
| * Removes the specified element from this set (optional operation). If | |
| * an element e exists, <code>o == null ? e == null : o.equals(e)</code>, | |
| * it is removed from the set. | |
| * | |
| * @param o the object to remove | |
| * @return true if the set changed (an object was removed) | |
| * @throws UnsupportedOperationException if this operation is not allowed | |
| * @throws ClassCastException if the type of o is not a valid type | |
| * for this set. | |
| * @throws NullPointerException if o is null and this set doesn't allow | |
| * the removal of a null value. | |
| */ | |
| boolean remove(Object o); | |
| /** | |
| * Removes from this set all elements contained in the specified collection | |
| * (optional operation). If the argument is a set, this returns the | |
| * <i>asymmetric set difference</i> of the two sets. | |
| * | |
| * @param c the collection to remove from this set | |
| * @return true if this set changed as a result | |
| * @throws UnsupportedOperationException if this operation is not allowed | |
| * @throws NullPointerException if c is null | |
| * @throws ClassCastException if the type of any element in c is not | |
| * a valid type for this set. | |
| * @throws NullPointerException if some element of c is null and this | |
| * set doesn't support removing null values. | |
| * @see #remove(Object) | |
| */ | |
| boolean removeAll(Collection c); | |
| /** | |
| * Retains only the elements in this set that are also in the specified | |
| * collection (optional operation). If the argument is also a set, this | |
| * performs the <i>intersection</i> of the two sets. | |
| * | |
| * @param c the collection to keep | |
| * @return true if this set was modified | |
| * @throws UnsupportedOperationException if this operation is not allowed | |
| * @throws NullPointerException if c is null | |
| * @throws ClassCastException if the type of any element in c is not | |
| * a valid type for this set. | |
| * @throws NullPointerException if some element of c is null and this | |
| * set doesn't support retaining null values. | |
| * @see #remove(Object) | |
| */ | |
| boolean retainAll(Collection c); | |
| /** | |
| * Returns the number of elements in the set. If there are more | |
| * than Integer.MAX_VALUE mappings, return Integer.MAX_VALUE. This is | |
| * the <i>cardinality</i> of the set. | |
| * | |
| * @return the number of elements | |
| */ | |
| int size(); | |
| /** | |
| * Returns an array containing the elements of this set. If the set | |
| * makes a guarantee about iteration order, the array has the same | |
| * order. The array is distinct from the set; modifying one does not | |
| * affect the other. | |
| * | |
| * @return an array of this set's elements | |
| * @see #toArray(Object[]) | |
| */ | |
| Object[] toArray(); | |
| /** | |
| * Returns an array containing the elements of this set, of the same runtime | |
| * type of the argument. If the given set is large enough, it is reused, | |
| * and null is inserted in the first unused slot. Otherwise, reflection | |
| * is used to build a new array. If the set makes a guarantee about iteration | |
| * order, the array has the same order. The array is distinct from the set; | |
| * modifying one does not affect the other. | |
| * | |
| * @param a the array to determine the return type; if it is big enough | |
| * it is used and returned | |
| * @return an array holding the elements of the set | |
| * @throws ArrayStoreException if the runtime type of a is not a supertype | |
| * of all elements in the set | |
| * @throws NullPointerException if a is null | |
| * @see #toArray() | |
| */ | |
| Object[] toArray(Object[] a); | |
| } |