com.google.common.collect

Class AbstractSequentialIterator<T>

java.lang.Object

com.google.common.collect.UnmodifiableIterator<T>

com.google.common.collect.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 Summary

Constructors

Modifier	Constructor and Description
protected	AbstractSequentialIterator(T firstOrNull) Creates a new iterator with the given first element, or, if firstOrNull is null, creates a new empty iterator.

Method Summary

Modifier and Type	Method and Description
protected abstract T	computeNext(T previous) Returns the element that follows previous, or returns null if no elements remain.
boolean	hasNext() Returns true if the iteration has more elements.
T	next() Returns the next element in the iteration.

Methods inherited from class com.google.common.collect.UnmodifiableIterator

remove

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Iterator

forEachRemaining

Constructor Detail

AbstractSequentialIterator

protected AbstractSequentialIterator(@NullableDecl
                                     T firstOrNull)

Creates a new iterator with the given first element, or, if firstOrNull is null, creates a new empty iterator.

Method Detail

computeNext

@NullableDecl
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