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## org.apache.commons.collections.iterators
Class ArrayListIterator

    java.lang.Object
      org.apache.commons.collections.iterators.ArrayIterator
          org.apache.commons.collections.iterators.ArrayListIterator

All Implemented Interfaces:
  java.util.Iterator, java.util.ListIterator, ResettableIterator, ResettableListIterator

    public class ArrayListIterator

extends ArrayIterator
implements java.util.ListIterator, ResettableListIterator

Implements a `ListIterator` over an array.

The array can be either an array of object or of primitives. If you know that you have an object array, the `ObjectArrayListIterator` class is a better choice, as it will perform better.

This iterator does not support `add(Object)` or `ArrayIterator.remove()`, as the array cannot be changed in size. The `set(Object)` method is supported however.

Since:
  Commons Collections 3.0
Version:
  $Revision: 647116 $ $Date: 2008-04-11 12:23:08 +0100 (Fri, 11 Apr 2008) $
Author:
  Neil O'Toole, Stephen Colebourne, Phil Steitz
See Also:
  `ArrayIterator`, `Iterator`, `ListIterator`

Field Summary
`protected int` | `lastItemIndex` Holds the index of the last item returned by a call to `next()` or `previous()`.

Fields inherited from class org.apache.commons.collections.iterators.ArrayIterator
`array, endIndex, index, startIndex`

Constructor Summary
`ArrayListIterator()` Constructor for use with `setArray`.
`ArrayListIterator(java.lang.Object array)` Constructs an ArrayListIterator that will iterate over the values in the specified array.
`ArrayListIterator(java.lang.Object array, int startIndex)` Constructs an ArrayListIterator that will iterate over the values in the specified array from a specific start index.
`ArrayListIterator(java.lang.Object array, int startIndex, int endIndex)` Construct an ArrayListIterator that will iterate over a range of values in the specified array.

Method Summary
`void` | `add(java.lang.Object o)` This iterator does not support modification of its backing collection, 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.
`java.lang.Object` | `next()` Gets the next element from the array.
`int` | `nextIndex()` Gets the next index to be retrieved.
`java.lang.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(java.lang.Object o)` Sets the element under the cursor.

Methods inherited from class org.apache.commons.collections.iterators.ArrayIterator
`checkBound, getArray, hasNext, remove, setArray`

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

Field Detail

### 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(java.lang.Object)` method.

Constructor Detail

### ArrayListIterator

    public ArrayListIterator()

  Constructor for use with `setArray`.

  Using this constructor, the iterator is equivalent to an empty iterator until `ArrayIterator.setArray(Object)` is called to establish the array to iterate over.

### ArrayListIterator

    public ArrayListIterator(java.lang.Object array)

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

  Parameters:
    `array` - the array to iterate over
  Throws:
    `java.lang.IllegalArgumentException` - if `array` is not an array.
    `java.lang.NullPointerException` - if `array` is `null`

### ArrayListIterator

    public ArrayListIterator(java.lang.Object array,
                             int startIndex)

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

  Parameters:
    `array` - the array to iterate over
    `startIndex` - the index to start iterating at
  Throws:
    `java.lang.IllegalArgumentException` - if `array` is not an array.
    `java.lang.NullPointerException` - if `array` is `null`
    `java.lang.IndexOutOfBoundsException` - if the start index is out of bounds

### ArrayListIterator

    public ArrayListIterator(java.lang.Object array,
                             int startIndex,
                             int endIndex)

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

  Parameters:
    `array` - the array to iterate over
    `startIndex` - the index to start iterating at
    `endIndex` - the index (exclusive) to finish iterating at
  Throws:
    `java.lang.IllegalArgumentException` - if `array` is not an array.
    `java.lang.IndexOutOfBoundsException` - if the start or end index is out of bounds
    `java.lang.IllegalArgumentException` - if end index is before the start
    `java.lang.NullPointerException` - if `array` is `null`

Method Detail

### hasPrevious

    public boolean hasPrevious()

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

  Specified by:
    `hasPrevious` in interface `java.util.ListIterator`
  Returns:
    true if there is a previous element to return

### previous

    public java.lang.Object previous()

  Gets the previous element from the array.

  Specified by:
    `previous` in interface `java.util.ListIterator`
  Returns:
    the previous element
  Throws:
    `java.util.NoSuchElementException` - if there is no previous element

### next

    public java.lang.Object next()

  Gets the next element from the array.

  Specified by:
    `next` in interface `java.util.Iterator`
  Specified by:
    `next` in interface `java.util.ListIterator`
  Overrides:
    `next` in class `ArrayIterator`
  Returns:
    the next element
  Throws:
    `java.util.NoSuchElementException` - if there is no next element

### nextIndex

    public int nextIndex()

  Gets the next index to be retrieved.

  Specified by:
    `nextIndex` in interface `java.util.ListIterator`
  Returns:
    the index of the item to be retrieved next

### previousIndex

    public int previousIndex()

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

  Specified by:
    `previousIndex` in interface `java.util.ListIterator`
  Returns:
    the index of the item to be retrieved next

### add

    public void add(java.lang.Object o)

  This iterator does not support modification of its backing collection, and so will always throw an `UnsupportedOperationException` when this method is invoked.

  Specified by:
    `add` in interface `java.util.ListIterator`
  Throws:
    `java.lang.UnsupportedOperationException` - always thrown.
  See Also:
    `ListIterator.set(java.lang.Object)`

### set

    public void set(java.lang.Object o)

  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.

  Specified by:
    `set` in interface `java.util.ListIterator`
  See Also:
    `ListIterator.set(java.lang.Object)`

### reset

    public void reset()

  Resets the iterator back to the start index.

  Specified by:
    `reset` in interface `ResettableIterator`
  Specified by:
    `reset` in interface `ResettableListIterator`
  Overrides:
    `reset` in class `ArrayIterator`

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