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org.apache.commons.collections.iterators

Class ObjectArrayListIterator

java.lang.Object
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+--org.apache.commons.collections.iterators.ObjectArrayIterator
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   +--org.apache.commons.collections.iterators.ObjectArrayListIterator

All Implemented Interfaces:
Iterator, ListIterator, ResettableIterator, ResettableListIterator


public class ObjectArrayListIterator
extends ObjectArrayIterator
implements ListIterator, ResettableListIterator

Implements a ListIterator over an array of objects.

This iterator does not support add or remove, as the object array cannot be structurally modified. The set method is supported however.

The iterator implements a reset method, allowing the reset of the iterator back to the start if required.

Since:
Commons Collections 3.0
Authors:
Neil O'Toole
Stephen Colebourne
Phil Steitz
See Also:
org.apache.commons.collections.iterators.ObjectArrayIterator
java.util.Iterator
java.util.ListIterator

Field Summary

int

lastItemIndex

Holds the index of the last item returned by a call to next() or previous().

Constructor Summary

ObjectArrayListIterator()

Constructor for use with setArray.

ObjectArrayListIterator(Object[] array)

Constructs an ObjectArrayListIterator that will iterate over the values in the specified array.

ObjectArrayListIterator(Object[] array, int start)

Constructs an ObjectArrayListIterator that will iterate over the values in the specified array from a specific start index.

ObjectArrayListIterator(Object[] array, int start, int end)

Construct an ObjectArrayListIterator that will iterate over a range of values in the specified array.

Method Summary

void

add(Object obj)

This iterator does not support modification of its backing array's size, and so will always throw an UnsupportedOperationException when this method is invoked.

boolean

hasPrevious()

Returns true if there are previous elements to return from the array.

Object

next()

Gets the next element from the array.

int

nextIndex()

Gets the next index to be retrieved.

Object

previous()

Gets the previous element from the array.

int

previousIndex()

Gets the index of the item to be retrieved if #previous() is called.

void

reset()

Resets the iterator back to the start index.

void

set(Object obj)

Sets the element under the cursor.

Field Details

lastItemIndex

protected int lastItemIndex

Holds the index of the last item returned by a call to next() or previous(). This is set to -1 if neither method has yet been invoked. lastItemIndex is used to to implement the set method.

Constructor Details

ObjectArrayListIterator

public ObjectArrayListIterator()

Constructor for use with setArray.

Using this constructor, the iterator is equivalent to an empty iterator until setArray is called to establish the array to iterate over.


ObjectArrayListIterator

public ObjectArrayListIterator(Object[] array, int start, int end)

Construct an ObjectArrayListIterator that will iterate over a range of values in the specified array.

Parameters:
array - the array to iterate over
start - the index to start iterating at
end - the index (exclusive) to finish iterating at
Throws:
- if the start or end index is out of bounds
- if end index is before the start
- if array is null

ObjectArrayListIterator

public ObjectArrayListIterator(Object[] array, int start)

Constructs an ObjectArrayListIterator that will iterate over the values in the specified array from a specific start index.

Parameters:
array - the array to iterate over
start - the index to start iterating at
Throws:
- if array is null
- if the start index is out of bounds

ObjectArrayListIterator

public ObjectArrayListIterator(Object[] array)

Constructs an ObjectArrayListIterator that will iterate over the values in the specified array.

Parameters:
array - the array to iterate over
Throws:
- if array is null

Method Details

add

public void add(Object obj)

This iterator does not support modification of its backing array's size, and so will always throw an UnsupportedOperationException when this method is invoked.

Parameters:
obj - the object to add
Throws:
- always thrown.

hasPrevious

public boolean hasPrevious()

Returns true if there are previous elements to return from the array.

Returns:
true if there is a previous element to return

next

public Object next()

Gets the next element from the array.

Returns:
the next element
Throws:
- if there is no next element

nextIndex

public int nextIndex()

Gets the next index to be retrieved.

Returns:
the index of the item to be retrieved next

previous

public Object previous()

Gets the previous element from the array.

Returns:
the previous element
Throws:
- if there is no previous element

previousIndex

public int previousIndex()

Returns:
the index of the item to be retrieved next

reset

public void reset()

Resets the iterator back to the start index.


set

public void set(Object obj)

Sets the element under the cursor.

This method sets the element that was returned by the last call to next() of previous(). Note:ListIterator implementations that support add() and remove() only allow set() to be called once per call to next() or previous (see the ListIterator javadoc for more details). Since this implementation does not support add() or remove(), set() may be called as often as desired.

Parameters:
obj - the object to set into the array
Throws:
- if next() has not yet been called.
- if the object type is unsuitable for the array