This class provides skeletal implementations of some Queue operations. The implementations in this class are appropriate when the base implementation does not allow null elements. Methods add , remove , and element are based on offer , poll , and peek , respectively but throw exceptions instead of indicating failure via false or null returns.

A Queue implementation that extends this class must minimally define a method offer(Object) which does not permit insertion of null elements, along with methods peek() , poll() , size() , and a iterator() supporting remove() . Typically, additional methods will be overridden as well. If these requirements cannot be met, consider instead subclassing AbstractCollection .

This class is a member of the Java Collections Framework.