E - the type of elements maintained by this setpublic abstract class AbstractSet<E> extends AbstractCollection<E> implements Set<E>
The process of implementing a set by extending this class is identical to that of implementing a Collection by extending AbstractCollection, except that all of the methods and constructors in subclasses of this class must obey the additional constraints imposed by the Set interface (for instance, the add method must not permit addition of multiple instances of an object to a set).
Note that this class does not override any of the implementations from the AbstractCollection class. It merely adds implementations for equals and hashCode.
This class is a member of the Java Collections Framework.
Collection,
AbstractCollection,
Set| Modifier | Constructor and Description |
|---|---|
protected |
AbstractSet()
Sole constructor.
|
| Modifier and Type | Method and Description |
|---|---|
boolean |
equals(Object o)
Compares the specified object with this set for equality.
|
int |
hashCode()
Returns the hash code value for this set.
|
boolean |
removeAll(Collection<?> c)
Removes from this set all of its elements that are contained in the
specified collection (optional operation).
|
add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, retainAll, size, toArray, toArray, toStringprotected AbstractSet()
public boolean equals(Object o)
This implementation first checks if the specified object is this set; if so it returns true. Then, it checks if the specified object is a set whose size is identical to the size of this set; if not, it returns false. If so, it returns containsAll((Collection) o).
equals in interface Collection<E>equals in interface Set<E>equals in class Objecto - object to be compared for equality with this setObject.hashCode(),
HashMappublic int hashCode()
Object.hashCode().
This implementation iterates over the set, calling the hashCode method on each element in the set, and adding up the results.
hashCode in interface Collection<E>hashCode in interface Set<E>hashCode in class ObjectObject.equals(Object),
Set.equals(Object)public boolean removeAll(Collection<?> c)
This implementation determines which is the smaller of this set and the specified collection, by invoking the size method on each. If this set has fewer elements, then the implementation iterates over this set, checking each element returned by the iterator in turn to see if it is contained in the specified collection. If it is so contained, it is removed from this set with the iterator's remove method. If the specified collection has fewer elements, then the implementation iterates over the specified collection, removing from this set each element returned by the iterator, using this set's remove method.
Note that this implementation will throw an UnsupportedOperationException if the iterator returned by the iterator method does not implement the remove method.
removeAll in interface Collection<E>removeAll in interface Set<E>removeAll in class AbstractCollection<E>c - collection containing elements to be removed from this setUnsupportedOperationException - if the removeAll operation
is not supported by this setClassCastException - if the class of an element of this set
is incompatible with the specified collection (optional)NullPointerException - if this set contains a null element and the
specified collection does not permit null elements (optional),
or if the specified collection is nullAbstractCollection.remove(Object),
AbstractCollection.contains(Object) Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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