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java.lang.Object org.apache.commons.collections.iterators.IteratorChain<E>
public class IteratorChain<E>
An IteratorChain is an Iterator that wraps a number of Iterators.
This class makes multiple iterators look like one to the caller When any method from the Iterator interface is called, the IteratorChain will delegate to a single underlying Iterator. The IteratorChain will invoke the Iterators in sequence until all Iterators are exhausted. Under many circumstances, linking Iterators together in this manner is more efficient (and convenient) than reading out the contents of each Iterator into a List and creating a new Iterator. Calling a method that adds new Iteratorafter a method in the Iterator interface has been called will result in an UnsupportedOperationException. Subclasses should take care to not alter the underlying List of Iterators. NOTE: As from version 3.0, the IteratorChain may contain no iterators. In this case the class will function as an empty iterator.
Field Summary | |
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protected Iterator<? extends E> |
currentIterator
The current iterator |
protected int |
currentIteratorIndex
The index of the current iterator |
protected boolean |
isLocked
ComparatorChain is "locked" after the first time compare(Object,Object) is called |
protected List<Iterator<? extends E>> |
iteratorChain
The chain of iterators |
protected Iterator<? extends E> |
lastUsedIterator
The "last used" Iterator is the Iterator upon which next() or hasNext() was most recently called used for the remove() operation only |
Constructor Summary | |
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IteratorChain()
Construct an IteratorChain with no Iterators. |
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IteratorChain(Collection<Iterator<? extends E>> iterators)
Constructs a new IteratorChain over the collection
of iterators. |
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IteratorChain(Iterator<? extends E> iterator)
Construct an IteratorChain with a single Iterator. |
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IteratorChain(Iterator<? extends E>[] iterators)
Constructs a new IteratorChain over the array
of iterators. |
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IteratorChain(Iterator<? extends E> a,
Iterator<? extends E> b)
Constructs a new IteratorChain over the two
given iterators. |
Method Summary | |
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void |
addIterator(Iterator<? extends E> iterator)
Add an Iterator to the end of the chain |
List<Iterator<? extends E>> |
getIterators()
Get the list of Iterators (unmodifiable) |
boolean |
hasNext()
Return true if any Iterator in the IteratorChain has a remaining element. |
boolean |
isLocked()
Determine if modifications can still be made to the IteratorChain. |
E |
next()
Returns the next Object of the current Iterator |
void |
remove()
Removes from the underlying collection the last element returned by the Iterator. |
void |
setIterator(int index,
Iterator<? extends E> iterator)
Set the Iterator at the given index |
int |
size()
Number of Iterators in the current IteratorChain. |
protected void |
updateCurrentIterator()
Updates the current iterator field to ensure that the current Iterator is not exhausted |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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protected final List<Iterator<? extends E>> iteratorChain
protected int currentIteratorIndex
protected Iterator<? extends E> currentIterator
protected Iterator<? extends E> lastUsedIterator
protected boolean isLocked
Constructor Detail |
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public IteratorChain()
addIterator(Iterator)
to add
some iterators after using this constructor.
public IteratorChain(Iterator<? extends E> iterator)
iterator
- first Iterator in the IteratorChain
NullPointerException
- if the iterator is nullpublic IteratorChain(Iterator<? extends E> a, Iterator<? extends E> b)
IteratorChain
over the two
given iterators.
a
- the first child iteratorb
- the second child iterator
NullPointerException
- if either iterator is nullpublic IteratorChain(Iterator<? extends E>[] iterators)
IteratorChain
over the array
of iterators.
iterators
- the array of iterators
NullPointerException
- if iterators array is or contains nullpublic IteratorChain(Collection<Iterator<? extends E>> iterators)
IteratorChain
over the collection
of iterators.
iterators
- the collection of iterators
NullPointerException
- if iterators collection is or contains null
ClassCastException
- if iterators collection doesn't contain an iteratorMethod Detail |
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public void addIterator(Iterator<? extends E> iterator)
iterator
- Iterator to add
IllegalStateException
- if I've already started iterating
NullPointerException
- if the iterator is nullpublic void setIterator(int index, Iterator<? extends E> iterator) throws IndexOutOfBoundsException
index
- index of the Iterator to replaceiterator
- Iterator to place at the given index
IndexOutOfBoundsException
- if index < 0 or index > size()
IllegalStateException
- if I've already started iterating
NullPointerException
- if the iterator is nullpublic List<Iterator<? extends E>> getIterators()
public int size()
public boolean isLocked()
protected void updateCurrentIterator()
public boolean hasNext()
hasNext
in interface Iterator<E>
public E next()
next
in interface Iterator<E>
NoSuchElementException
- if all the Iterators are exhaustedpublic void remove()
remove
in interface Iterator<E>
UnsupportedOperationException
- if the remove operator is not supported by the underlying Iterator
IllegalStateException
- if the next method has not yet been called, or the remove method has
already been called after the last call to the next method.
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