Package com.github.javaparser.printer.lexicalpreservation

Class PeekingIterator<E>

java.lang.Object

com.github.javaparser.printer.lexicalpreservation.PeekingIterator<E>

Type Parameters:

E - the type of elements returned by this iterator.

All Implemented Interfaces:

LookaheadIterator<E>, Iterator<E>, ListIterator<E>

public class PeekingIterator<E>
extends Object
implements ListIterator<E>, LookaheadIterator<E>

Decorates an iterator to support one-element lookahead while iterating.

The decorator supports the removal operation, but an IllegalStateException will be thrown if remove(), #add(), #set()} is called directly after a call to peek() or element().

Since:

4.0

Constructor Summary

Constructors

Constructor	Description
PeekingIterator(List<E> list)	Constructor.
PeekingIterator(ListIterator<E> iterator)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	add(E e)
int	currentIndex()
E	element()	Returns the next element in iteration without advancing the underlying iterator.
boolean	hasNext()
boolean	hasPrevious()
E	next()
int	nextIndex()
E	peek()	Returns the next element in iteration without advancing the underlying iterator.
<E> PeekingIterator<E>	peekingIterator(ListIterator<E> iterator)	Decorates the specified iterator to support one-element lookahead.
E	previous()
int	previousIndex()
void	remove()
void	set(E e)

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

PeekingIterator

public PeekingIterator(ListIterator<E> iterator)

Constructor.

Parameters:

iterator - the iterator to decorate

PeekingIterator

public PeekingIterator(List<E> list)

Constructor.

Parameters:

list - the provider of the iterator to decorate

Method Detail

peekingIterator

public <E> PeekingIterator<E> peekingIterator(ListIterator<E> iterator)

Decorates the specified iterator to support one-element lookahead.

If the iterator is already a PeekingIterator it is returned directly.

Type Parameters:

E - the element type

Parameters:

iterator - the iterator to decorate

Returns:

a new peeking iterator

Throws:

NullPointerException - if the iterator is null

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator<E>

Specified by:

hasNext in interface ListIterator<E>

peek

public E peek()

Returns the next element in iteration without advancing the underlying iterator. If the iterator is already exhausted, null will be returned.

Note: this method does not throw a NoSuchElementException if the iterator is already exhausted. If you want such a behavior, use element() instead.

The rationale behind this is to follow the Queue interface which uses the same terminology.

Specified by:

peek in interface LookaheadIterator<E>

Returns:

the next element from the iterator

element

public E element()

Returns the next element in iteration without advancing the underlying iterator. If the iterator is already exhausted, null will be returned.

Specified by:

element in interface LookaheadIterator<E>

Returns:

the next element from the iterator

Throws:

NoSuchElementException - if the iterator is already exhausted according to hasNext()

next

public E next()

Specified by:

next in interface Iterator<E>

Specified by:

next in interface ListIterator<E>

remove

public void remove()

Specified by:

remove in interface Iterator<E>

Specified by:

remove in interface ListIterator<E>

Throws:

IllegalStateException - if peek() or element() has been called prior to the call to remove()

hasPrevious

public boolean hasPrevious()

Specified by:

hasPrevious in interface ListIterator<E>

previous

public E previous()

Specified by:

previous in interface ListIterator<E>

nextIndex

public int nextIndex()

Specified by:

nextIndex in interface ListIterator<E>

currentIndex

public int currentIndex()

previousIndex

public int previousIndex()

Specified by:

previousIndex in interface ListIterator<E>

set

public void set(E e)

Specified by:

set in interface ListIterator<E>

add

public void add(E e)

Specified by:

add in interface ListIterator<E>