AbstractSet<E> (GNU Classpath 0.94-pre Documentation)

An abstract implementation of Set to make it easier to create your own implementations. In order to create a Set, subclass AbstractSet and implement the same methods that are required for AbstractCollection (although these methods must of course meet the requirements that Set puts on them - specifically, no element may be in the set more than once). This class simply provides implementations of equals() and hashCode() to fulfil the requirements placed on them by the Set interface.

Since: 1.2

UNKNOWN: updated to 1.4

Constructor Summary
protected	AbstractSet() The main constructor, for use by subclasses.

Method Summary
boolean	equals(Object o) Tests whether the given object is equal to this Set.
int	hashCode() Returns a hash code for this Set.
boolean	removeAll(Collection<?> c) Removes from this set all elements in the given collection (optional operation).

Constructor Detail

AbstractSet

The main constructor, for use by subclasses.

Method Detail

equals

Tests whether the given object is equal to this Set. This implementation first checks whether this set is the given object, and returns true if so. Otherwise, if o is a Set and is the same size as this one, it returns the result of calling containsAll on the given Set. Otherwise, it returns false.

Parameters: o the Object to be tested for equality with this Set

Returns: true if the given object is equal to this Set

hashCode

Returns a hash code for this Set. The hash code of a Set is the sum of the hash codes of all its elements, except that the hash code of null is defined to be zero. This implementation obtains an Iterator over the Set, and sums the results.

Returns: a hash code for this Set

removeAll

Removes from this set all elements in the given collection (optional operation). This implementation uses size() to determine the smaller collection. Then, if this set is smaller, it iterates over the set, calling Iterator.remove if the collection contains the element. If this set is larger, it iterates over the collection, calling Set.remove for all elements in the collection. Note that this operation will fail if a remove methods is not supported.

Parameters: c the collection of elements to remove

Returns: true if the set was modified as a result

Throws: UnsupportedOperationException if remove is not supported NullPointerException if the collection is null