E- the type of elements maintained by this set
public 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
|Modifier||Constructor and Description|
|Modifier and Type||Method and Description|
Compares the specified object with this set for equality.
Returns the hash code value for this set.
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, toString
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).
public int hashCode()
This implementation iterates over the set, calling the hashCode method on each element in the set, and adding up the results.
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.
c- collection containing elements to be removed from this set
UnsupportedOperationException- if the removeAll operation is not supported by this set
ClassCastException- 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 null