Package com.google.common.collect

Class AbstractSequentialIterator<T>

  • All Implemented Interfaces:
    Iterator<T>
    @GwtCompatible
public abstract class AbstractSequentialIterator<T>
extends UnmodifiableIterator<T>
    This class provides a skeletal implementation of the Iterator interface for sequences whose next element can always be derived from the previous element. Null elements are not supported, nor is the UnmodifiableIterator.remove() method.

    Example: 

    
 Iterator<Integer> powersOfTwo =
     new AbstractSequentialIterator<Integer>(1) {
       protected Integer computeNext(Integer previous) {
         return (previous == 1 << 30) ? null : previous * 2;
       }
     };
    Since:
    12.0 (in Guava as AbstractLinkedIterator since 8.0)
    Author:
    Chris Povirk

    • Constructor Detail

      • AbstractSequentialIterator

        protected AbstractSequentialIterator​(@CheckForNull
                                     T firstOrNull)
        Creates a new iterator with the given first element, or, if firstOrNull is null, creates a new empty iterator.

    • Method Detail

      • computeNext

        @CheckForNull
protected abstract T computeNext​(T previous)
        Returns the element that follows previous, or returns null if no elements remain. This method is invoked during each call to next() in order to compute the result of a future call to next().

      • hasNext

        public final boolean hasNext()
        Description copied from interface: java.util.Iterator
        Returns true if the iteration has more elements. (In other words, returns true if Iterator.next() would return an element rather than throwing an exception.)
        Returns:
        true if the iteration has more elements

      • next

        public final T next()
        Description copied from interface: java.util.Iterator
        Returns the next element in the iteration.
        Returns:
        the next element in the iteration