IteratorChain ("The Adobe AEM Quickstart and Web Application.")

java.lang.Object
- org.apache.commons.collections4.iterators.IteratorChain<E>

All Implemented Interfaces:

java.util.Iterator<E>
```
public class IteratorChain<E>
extends java.lang.Object
implements java.util.Iterator<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 Iterator after a method in the Iterator interface has been called will result in an UnsupportedOperationException.
NOTE: As from version 3.0, the IteratorChain may contain no iterators. In this case the class will function as an empty iterator.
NOTE: As from version 4.0, the IteratorChain stores the iterators in a queue and removes any reference to them as soon as they are not used anymore. Thus the methods setIterator(Iterator) and getIterators() have been removed and size() will return the number of remaining iterators in the queue.

Since:

2.1

Constructor Summary

Constructors
Constructor and Description
`IteratorChain()` Construct an IteratorChain with no Iterators.
`IteratorChain(java.util.Collection<java.util.Iterator<? extends E>> iteratorChain)` Constructs a new `IteratorChain` over the collection of iterators.
`IteratorChain(java.util.Iterator<? extends E>... iteratorChain)` Constructs a new `IteratorChain` over the array of iterators.
`IteratorChain(java.util.Iterator<? extends E> iterator)` Construct an IteratorChain with a single Iterator.
`IteratorChain(java.util.Iterator<? extends E> first, java.util.Iterator<? extends E> second)` Constructs a new `IteratorChain` over the two given iterators.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addIterator(java.util.Iterator<? extends E> iterator)` Add an Iterator to the end of the chain
`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.
`int`	`size()` Returns the remaining number of Iterators in the current IteratorChain.

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Iterator
forEachRemaining

- Constructor Detail
  - IteratorChain
```
public IteratorChain()
```
    Construct an IteratorChain with no Iterators.
    You will normally use addIterator(Iterator) to add some iterators after using this constructor.
  - IteratorChain
```
public IteratorChain(java.util.Iterator<? extends E> iterator)
```
    Construct an IteratorChain with a single Iterator.
    This method takes one iterator. The newly constructed iterator will iterate through that iterator. Thus calling this constructor on its own will have no effect other than decorating the input iterator.
    You will normally use addIterator(Iterator) to add some more iterators after using this constructor.
    
    Parameters:
    
    iterator - the first child iterator in the IteratorChain, not null
    
    Throws:
    
    java.lang.NullPointerException - if the iterator is null
  - IteratorChain
```
public IteratorChain(java.util.Iterator<? extends E> first,
                     java.util.Iterator<? extends E> second)
```
    Constructs a new IteratorChain over the two given iterators.
    This method takes two iterators. The newly constructed iterator will iterate through each one of the input iterators in turn.
    
    Parameters:
    
    first - the first child iterator in the IteratorChain, not null
    
    second - the second child iterator in the IteratorChain, not null
    
    Throws:
    
    java.lang.NullPointerException - if either iterator is null
  - IteratorChain
```
public IteratorChain(java.util.Iterator<? extends E>... iteratorChain)
```
    Constructs a new IteratorChain over the array of iterators.
    This method takes an array of iterators. The newly constructed iterator will iterate through each one of the input iterators in turn.
    
    Parameters:
    
    iteratorChain - the array of iterators, not null
    
    Throws:
    
    java.lang.NullPointerException - if iterators array is or contains null
  - IteratorChain
```
public IteratorChain(java.util.Collection<java.util.Iterator<? extends E>> iteratorChain)
```
    Constructs a new IteratorChain over the collection of iterators.
    This method takes a collection of iterators. The newly constructed iterator will iterate through each one of the input iterators in turn.
    
    Parameters:
    
    iteratorChain - the collection of iterators, not null
    
    Throws:
    
    java.lang.NullPointerException - if iterators collection is or contains null
    
    java.lang.ClassCastException - if iterators collection doesn't contain an iterator
- Method Detail
  - addIterator
```
public void addIterator(java.util.Iterator<? extends E> iterator)
```
    Add an Iterator to the end of the chain
    
    Parameters:
    
    iterator - Iterator to add
    
    Throws:
    
    java.lang.IllegalStateException - if I've already started iterating
    
    java.lang.NullPointerException - if the iterator is null
  - size
```
public int size()
```
    Returns the remaining number of Iterators in the current IteratorChain.
    
    Returns:
    
    Iterator count
  - isLocked
```
public boolean isLocked()
```
    Determine if modifications can still be made to the IteratorChain. IteratorChains cannot be modified once they have executed a method from the Iterator interface.
    
    Returns:
    
    true if IteratorChain cannot be modified, false if it can
  - hasNext
```
public boolean hasNext()
```
    Return true if any Iterator in the IteratorChain has a remaining element.
    
    Specified by:
    
    hasNext in interface java.util.Iterator<E>
    
    Returns:
    
    true if elements remain
  - next
```
public E next()
```
    Returns the next Object of the current Iterator
    
    Specified by:
    
    next in interface java.util.Iterator<E>
    
    Returns:
    
    Object from the current Iterator
    
    Throws:
    
    java.util.NoSuchElementException - if all the Iterators are exhausted
  - remove
```
public void remove()
```
    Removes from the underlying collection the last element returned by the Iterator. As with next() and hasNext(), this method calls remove() on the underlying Iterator. Therefore, this method may throw an UnsupportedOperationException if the underlying Iterator does not support this method.
    
    Specified by:
    
    remove in interface java.util.Iterator<E>
    
    Throws:
    
    java.lang.UnsupportedOperationException - if the remove operator is not supported by the underlying Iterator
    
    java.lang.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.

Class IteratorChain<E>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Iterator

Constructor Detail

IteratorChain

IteratorChain

IteratorChain

IteratorChain

IteratorChain

Method Detail

addIterator

size

isLocked

hasNext

next

remove