CollatingIterator (Apache Commons Collections 3.2.2 API)

java.lang.Object
- org.apache.commons.collections.iterators.CollatingIterator

All Implemented Interfaces:

Iterator
```
public class CollatingIterator
extends Object
implements Iterator
```
Provides an ordered iteration over the elements contained in a collection of ordered Iterators.
Given two ordered Iterator instances A and B, the next() method on this iterator will return the lesser of A.next() and B.next().

Since:

Commons Collections 2.1

Version:

$Revision: 972404 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $

Author:

Rodney Waldhoff, Stephen Colebourne

Constructor Summary

Constructors
Constructor and Description
`CollatingIterator()` Constructs a new `CollatingIterator`.
`CollatingIterator(Comparator comp)` Constructs a new `CollatingIterator` that will used the specified comparator for ordering.
`CollatingIterator(Comparator comp, Collection iterators)` Constructs a new `CollatingIterator` that will use the specified comparator to provide ordered iteration over the collection of iterators.
`CollatingIterator(Comparator comp, int initIterCapacity)` Constructs a new `CollatingIterator` that will used the specified comparator for ordering and have the specified initial capacity.
`CollatingIterator(Comparator comp, Iterator[] iterators)` Constructs a new `CollatingIterator` that will use the specified comparator to provide ordered iteration over the array of iterators.
`CollatingIterator(Comparator comp, Iterator a, Iterator b)` Constructs a new `CollatingIterator` that will use the specified comparator to provide ordered iteration over the two given iterators.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`addIterator(Iterator iterator)` Adds the given `Iterator` to the iterators being collated.
`Comparator`	`getComparator()` Gets the `Comparator` by which collatation occurs.
`List`	`getIterators()` Gets the list of Iterators (unmodifiable).
`boolean`	`hasNext()` Returns `true` if any child iterator has remaining elements.
`Object`	`next()` Returns the next ordered element from a child iterator.
`void`	`remove()` Removes the last returned element from the child iterator that produced it.
`void`	`setComparator(Comparator comp)` Sets the `Comparator` by which collation occurs.
`void`	`setIterator(int index, Iterator iterator)` Sets the iterator at the given index.

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

- Constructor Detail
  - CollatingIterator
```
public CollatingIterator()
```
    Constructs a new CollatingIterator. Natural sort order will be used, and child iterators will have to be manually added using the addIterator(Iterator) method.
  - CollatingIterator
```
public CollatingIterator(Comparator comp)
```
    Constructs a new CollatingIterator that will used the specified comparator for ordering. Child iterators will have to be manually added using the addIterator(Iterator) method.
    
    Parameters:
    comp - the comparator to use to sort, or null to use natural sort order
  - CollatingIterator
```
public CollatingIterator(Comparator comp,
                 int initIterCapacity)
```
    Constructs a new CollatingIterator that will used the specified comparator for ordering and have the specified initial capacity. Child iterators will have to be manually added using the addIterator(Iterator) method.
    
    Parameters:
    comp - the comparator to use to sort, or null to use natural sort order
    initIterCapacity - the initial capacity for the internal list of child iterators
  - CollatingIterator
```
public CollatingIterator(Comparator comp,
                 Iterator a,
                 Iterator b)
```
    Constructs a new CollatingIterator that will use the specified comparator to provide ordered iteration over the two given iterators.
    
    Parameters:
    comp - the comparator to use to sort, or null to use natural sort order
    a - the first child ordered iterator
    b - the second child ordered iterator
    
    Throws:
    
    NullPointerException - if either iterator is null
  - CollatingIterator
```
public CollatingIterator(Comparator comp,
                 Iterator[] iterators)
```
    Constructs a new CollatingIterator that will use the specified comparator to provide ordered iteration over the array of iterators.
    
    Parameters:
    comp - the comparator to use to sort, or null to use natural sort order
    iterators - the array of iterators
    
    Throws:
    
    NullPointerException - if iterators array is or contains null
  - CollatingIterator
```
public CollatingIterator(Comparator comp,
                 Collection iterators)
```
    Constructs a new CollatingIterator that will use the specified comparator to provide ordered iteration over the collection of iterators.
    
    Parameters:
    comp - the comparator to use to sort, or null to use natural sort order
    iterators - the collection of iterators
    
    Throws:
    
    NullPointerException - if the iterators collection is or contains null
    
    ClassCastException - if the iterators collection contains an element that's not an Iterator
- Method Detail
  - addIterator
```
public void addIterator(Iterator iterator)
```
    Adds the given Iterator to the iterators being collated.
    
    Parameters:
    iterator - the iterator to add to the collation, must not be null
    
    Throws:
    
    IllegalStateException - if iteration has started
    
    NullPointerException - if the iterator is null
  - setIterator
```
public void setIterator(int index,
               Iterator iterator)
```
    Sets the iterator at the given index.
    
    Parameters:
    index - index of the Iterator to replace
    iterator - Iterator to place at the given index
    
    Throws:
    
    IndexOutOfBoundsException - if index < 0 or index > size()
    
    IllegalStateException - if iteration has started
    
    NullPointerException - if the iterator is null
  - getIterators
```
public List getIterators()
```
    Gets the list of Iterators (unmodifiable).
    
    Returns:
    the unmodifiable list of iterators added
  - getComparator
```
public Comparator getComparator()
```
    Gets the Comparator by which collatation occurs.
  - setComparator
```
public void setComparator(Comparator comp)
```
    Sets the Comparator by which collation occurs.
    
    Throws:
    
    IllegalStateException - if iteration has started
  - hasNext
```
public boolean hasNext()
```
    Returns true if any child iterator has remaining elements.
    
    Specified by:
    
    hasNext in interface Iterator
    
    Returns:
    true if this iterator has remaining elements
  - next
```
public Object next()
            throws NoSuchElementException
```
    Returns the next ordered element from a child iterator.
    
    Specified by:
    
    next in interface Iterator
    
    Returns:
    the next ordered element
    
    Throws:
    
    NoSuchElementException - if no child iterator has any more elements
  - remove
```
public void remove()
```
    Removes the last returned element from the child iterator that produced it.
    
    Specified by:
    
    remove in interface Iterator
    
    Throws:
    
    IllegalStateException - if there is no last returned element, or if the last returned element has already been removed

Class CollatingIterator

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

CollatingIterator

CollatingIterator

CollatingIterator

CollatingIterator

CollatingIterator

CollatingIterator

Method Detail

addIterator

setIterator

getIterators

getComparator

setComparator

hasNext

next

remove