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src/java.base/share/classes/java/util/Set.java
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*** 25,61 ****
package java.util;
/**
* A collection that contains no duplicate elements. More formally, sets
! * contain no pair of elements <code>e1</code> and <code>e2</code> such that
! * <code>e1.equals(e2)</code>, and at most one null element. As implied by
* its name, this interface models the mathematical <i>set</i> abstraction.
*
! * <p>The <tt>Set</tt> interface places additional stipulations, beyond those
! * inherited from the <tt>Collection</tt> interface, on the contracts of all
! * constructors and on the contracts of the <tt>add</tt>, <tt>equals</tt> and
! * <tt>hashCode</tt> methods. Declarations for other inherited methods are
* also included here for convenience. (The specifications accompanying these
! * declarations have been tailored to the <tt>Set</tt> 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 <tt>equals</tt> 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
! * <tt>NullPointerException</tt> or <tt>ClassCastException</tt>. 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
--- 25,61 ----
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
*** 85,116 ****
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 <tt>Integer.MAX_VALUE</tt> elements, returns
! * <tt>Integer.MAX_VALUE</tt>.
*
* @return the number of elements in this set (its cardinality)
*/
int size();
/**
! * Returns <tt>true</tt> if this set contains no elements.
*
! * @return <tt>true</tt> if this set contains no elements
*/
boolean isEmpty();
/**
! * Returns <tt>true</tt> if this set contains the specified element.
! * More formally, returns <tt>true</tt> if and only if this set
! * contains an element <tt>e</tt> such that
! * <tt>(o==null ? e==null : o.equals(e))</tt>.
*
* @param o element whose presence in this set is to be tested
! * @return <tt>true</tt> 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
--- 85,116 ----
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>(o==null ? e==null : o.equals(e))</code>.
*
* @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
*** 153,163 ****
* 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
! * <tt>null</tt>. (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
--- 153,163 ----
* 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
*** 166,184 ****
* <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 <tt>x</tt> is a set known to contain only strings.
* The following code can be used to dump the set into a newly allocated
! * array of <tt>String</tt>:
*
* <pre>
* String[] y = x.toArray(new String[0]);</pre>
*
! * Note that <tt>toArray(new Object[0])</tt> is identical in function to
! * <tt>toArray()</tt>.
*
* @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
--- 166,184 ----
* <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
*** 193,221 ****
// Modification Operations
/**
* Adds the specified element to this set if it is not already present
* (optional operation). More formally, adds the specified element
! * <tt>e</tt> to this set if the set contains no element <tt>e2</tt>
* such that
! * <tt>(e==null ? e2==null : e.equals(e2))</tt>.
* If this set already contains the element, the call leaves the set
! * unchanged and returns <tt>false</tt>. 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
! * <tt>null</tt>, 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 <tt>true</tt> if this set did not already contain the specified
* element
! * @throws UnsupportedOperationException if the <tt>add</tt> 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
--- 193,221 ----
// 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>(e==null ? e2==null : e.equals(e2))</code>.
* 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
*** 225,265 ****
boolean add(E e);
/**
* Removes the specified element from this set if it is present
! * (optional operation). More formally, removes an element <tt>e</tt>
* such that
! * <tt>(o==null ? e==null : o.equals(e))</tt>, if
! * this set contains such an element. Returns <tt>true</tt> 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 <tt>true</tt> 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 <tt>remove</tt> operation
* is not supported by this set
*/
boolean remove(Object o);
// Bulk Operations
/**
! * Returns <tt>true</tt> if this set contains all of the elements of the
* specified collection. If the specified collection is also a set, this
! * method returns <tt>true</tt> if it is a <i>subset</i> of this set.
*
* @param c collection to be checked for containment in this set
! * @return <tt>true</tt> 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>)
--- 225,265 ----
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>(o==null ? e==null : o.equals(e))</code>, 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>)
*** 273,291 ****
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 <tt>addAll</tt> 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 <tt>true</tt> if this set changed as a result of the call
*
! * @throws UnsupportedOperationException if the <tt>addAll</tt> 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
--- 273,291 ----
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
*** 303,314 ****
* 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 <tt>true</tt> if this set changed as a result of the call
! * @throws UnsupportedOperationException if the <tt>retainAll</tt> 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
--- 303,314 ----
* 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
*** 325,336 ****
* 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 <tt>true</tt> if this set changed as a result of the call
! * @throws UnsupportedOperationException if the <tt>removeAll</tt> 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
--- 325,336 ----
* 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
*** 344,382 ****
/**
* Removes all of the elements from this set (optional operation).
* The set will be empty after this call returns.
*
! * @throws UnsupportedOperationException if the <tt>clear</tt> method
* is not supported by this set
*/
void clear();
// Comparison and hashing
/**
* Compares the specified object with this set for equality. Returns
! * <tt>true</tt> 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 <tt>true</tt> 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 <tt>null</tt> element is defined to be zero.
! * This ensures that <tt>s1.equals(s2)</tt> implies that
! * <tt>s1.hashCode()==s2.hashCode()</tt> for any two sets <tt>s1</tt>
! * and <tt>s2</tt>, 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)
--- 344,382 ----
/**
* 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)
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