Summary of Classes and Interfaces - Absolute Java - page 1197

Iterator <T> iterator()
Returns an iterator for the calling object. (Iterators are discussed in Section 16.3.)
public Object[] toArray()
Returns an array containing all of the elements in the calling object. A new array should be
returned so that the calling object has no references to the returned array.
public <E> E[] toArray(E[] a)
Note that the type parameter E is not the same as T. So, E can be any reference type; it need
not be the type T in Collection <T>. For example, E might be an ancestor type of T.
Returns an array containing all of the elements in the calling object. The argument a is used
primarily to specify the type of the array returned. The exact details are described in the table for
the Collection <T> interface.
Throws:
ArrayStoreException if the type of a is not an ancestor type of the type of every element in
the calling object.
NullPointerException if a is null.
public int size()
Returns the number of elements in the calling object. If the calling object contains more than
Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.
ADDING AND REMOVING ELEMENTS
Although many are optional, the following methods are almost always implemented for classes
that implement the Set <T> interface.
public boolean add(T element) (Optional)
If element is not already in the calling object, element is added to the calling object and true is
returned. If element is in the calling object, the calling object is unchanged and false is returned.
Throws:
UnsupportedOperationException if the add method is not supported by the set.
ClassCastException if the class of element prevents it from being added to the set.
NullPointerException if element is null and the set does not support null elements.
IllegalArgumentException if some other aspect of element prevents it from being added
to this set.
public boolean addAll(Collection<? extends T> collectionToAdd) (Optional)
Ensures that the calling object contains all the elements in collectionToAdd. Returns true if the
calling object changed as a result of the call; returns false otherwise. Thus, if collectionToAdd is
a Set <T> , then the calling object is changed to the union of itself with collectionToAdd.
Throws:
UnsupportedOperationException if the addAll method is not supported by the set.
ClassCastException if the class of some element of collectionToAdd prevents it from
being added to the calling object.
NullPointerException if collectionToAdd contains one or more null elements and the
calling object does not support null elements, or if collectionToAdd is null.
IllegalArgumentException if some aspect of some element of collectionToAdd
prevents it from being added to the calling object.