Package nl.vpro.util

Class LazyIterator<T>

java.lang.Object

nl.vpro.util.LazyIterator<T>

All Implemented Interfaces:

AutoCloseable, Iterator<T>, CloseableIterator<T>, Counted, CountedIterator<T>

public class LazyIterator<T>
extends Object
implements CloseableIterator<T>, CountedIterator<T>

Wraps a supplier around an iterator. This way you can delay the instantiation of the actual iterator until the first call of hasNext() or next().

Author:

Michiel Meeuwissen

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	LazyIterator.Builder<T>

Nested classes/interfaces inherited from interface nl.vpro.util.CloseableIterator

CloseableIterator.WrappedCloseableIterator<S>, CloseableIterator.WrappedPeekingCloseableIterator<S>

Constructor Summary

Constructors

Constructor	Description
LazyIterator(Supplier<Iterator<T>> supplier)

Method Summary

Modifier and Type	Method	Description
static <T> LazyIterator.Builder<T>	builder()
void	close()
Long	getCount()	The current position.
@NonNull Optional<Long>	getSize()	The size, if known, of the collection this iterator is representing
boolean	hasNext()
T	next()
static <S> LazyIterator<S>	of(Supplier<Iterator<S>> supplier)

Methods inherited from class java.lang.Object

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

Methods inherited from interface nl.vpro.util.CountedIterator

getTotalSize, peeking, spliterator, stream

Methods inherited from interface java.util.Iterator

forEachRemaining, remove

Constructor Details

LazyIterator

public LazyIterator(Supplier<Iterator<T>> supplier)

Method Details

of

public static <S> LazyIterator<S> of(Supplier<Iterator<S>> supplier)

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator<T>

next

public T next()

Specified by:

next in interface Iterator<T>

getSize

public @NonNull Optional<Long> getSize()

Description copied from interface: CountedIterator

The size, if known, of the collection this iterator is representing

Specified by:

getSize in interface CountedIterator<T>

close

public void close()
           throws Exception

Specified by:

close in interface AutoCloseable

Specified by:

close in interface CountedIterator<T>

Throws:

Exception

builder

public static <T> LazyIterator.Builder<T> builder()

getCount

public Long getCount()

Description copied from interface: CountedIterator

The current position. Will return 1 after first successfull call to Iterator.next(), 2 after the second one, and so on. It will return 0 before the first call.

Specified by:

getCount in interface Counted

Specified by:

getCount in interface CountedIterator<T>