org.springframework.util

## Class AutoPopulatingList<E>

- java.lang.Object
- - org.springframework.util.AutoPopulatingList<E>

- All Implemented Interfaces:
    Serializable, Iterable<E>, Collection<E>, List<E>

      public class AutoPopulatingList<E>
      extends Object
      implements List<E>, Serializable

  Simple `List` wrapper class that allows for elements to be automatically populated as they are requested. This is particularly useful for data binding to `Lists`, allowing for elements to be created and added to the `List` in a "just in time" fashion.

  Note: This class is not thread-safe. To create a thread-safe version, use the `Collections.synchronizedList(java.util.List<T>)` utility methods.

  Inspired by `LazyList` from Commons Collections.

  Since:
    2.0
  Author:
    Rob Harrop, Juergen Hoeller
  See Also:
    Serialized Form

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `static interface` | `AutoPopulatingList.ElementFactory<E>` Factory interface for creating elements for an index-based access data structure such as a `List`.
    `static class` | `AutoPopulatingList.ElementInstantiationException` Exception to be thrown from ElementFactory.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `AutoPopulatingList(AutoPopulatingList.ElementFactory<E> elementFactory)` Creates a new `AutoPopulatingList` that is backed by a standard `ArrayList` and creates new elements on demand using the supplied `AutoPopulatingList.ElementFactory`.
    `AutoPopulatingList(Class<? extends E> elementClass)` Creates a new `AutoPopulatingList` that is backed by a standard `ArrayList` and adds new instances of the supplied `element Class` to the backing `List` on demand.
    `AutoPopulatingList(List<E> backingList, AutoPopulatingList.ElementFactory<E> elementFactory)` Creates a new `AutoPopulatingList` that is backed by the supplied `List` and creates new elements on demand using the supplied `AutoPopulatingList.ElementFactory`.
    `AutoPopulatingList(List<E> backingList, Class<? extends E> elementClass)` Creates a new `AutoPopulatingList` that is backed by the supplied `List` and adds new instances of the supplied `element Class` to the backing `List` on demand.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `add(E o)`
    `void` | `add(int index, E element)`
    `boolean` | `addAll(Collection<? extends E> c)`
    `boolean` | `addAll(int index, Collection<? extends E> c)`
    `void` | `clear()`
    `boolean` | `contains(Object o)`
    `boolean` | `containsAll(Collection c)`
    `boolean` | `equals(Object other)`
    `E` | `get(int index)` Get the element at the supplied index, creating it if there is no element at that index.
    `int` | `hashCode()`
    `int` | `indexOf(Object o)`
    `boolean` | `isEmpty()`
    `Iterator<E>` | `iterator()`
    `int` | `lastIndexOf(Object o)`
    `ListIterator<E>` | `listIterator()`
    `ListIterator<E>` | `listIterator(int index)`
    `E` | `remove(int index)`
    `boolean` | `remove(Object o)`
    `boolean` | `removeAll(Collection<?> c)`
    `boolean` | `retainAll(Collection<?> c)`
    `E` | `set(int index, E element)`
    `int` | `size()`
    `List<E>` | `subList(int fromIndex, int toIndex)`
    `Object[]` | `toArray()`
    `<T> T[]` | `toArray(T[] a)`

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### AutoPopulatingList

          public AutoPopulatingList(Class<? extends E> elementClass)

      Creates a new `AutoPopulatingList` that is backed by a standard `ArrayList` and adds new instances of the supplied `element Class` to the backing `List` on demand.

    - #### AutoPopulatingList

          public AutoPopulatingList(List<E> backingList,
                            Class<? extends E> elementClass)

      Creates a new `AutoPopulatingList` that is backed by the supplied `List` and adds new instances of the supplied `element Class` to the backing `List` on demand.

    - #### AutoPopulatingList

          public AutoPopulatingList(AutoPopulatingList.ElementFactory<E> elementFactory)

      Creates a new `AutoPopulatingList` that is backed by a standard `ArrayList` and creates new elements on demand using the supplied `AutoPopulatingList.ElementFactory`.

    - #### AutoPopulatingList

          public AutoPopulatingList(List<E> backingList,
                            AutoPopulatingList.ElementFactory<E> elementFactory)

      Creates a new `AutoPopulatingList` that is backed by the supplied `List` and creates new elements on demand using the supplied `AutoPopulatingList.ElementFactory`.

  - ### Method Detail

    - #### add

          public void add(int index,
                 E element)

      Specified by:
        `add` in interface `List<E>`

    - #### add

          public boolean add(E o)

      Specified by:
        `add` in interface `Collection<E>`
      Specified by:
        `add` in interface `List<E>`

    - #### addAll

          public boolean addAll(Collection<? extends E> c)

      Specified by:
        `addAll` in interface `Collection<E>`
      Specified by:
        `addAll` in interface `List<E>`

    - #### addAll

          public boolean addAll(int index,
                       Collection<? extends E> c)

      Specified by:
        `addAll` in interface `List<E>`

    - #### clear

          public void clear()

      Specified by:
        `clear` in interface `Collection<E>`
      Specified by:
        `clear` in interface `List<E>`

    - #### contains

          public boolean contains(Object o)

      Specified by:
        `contains` in interface `Collection<E>`
      Specified by:
        `contains` in interface `List<E>`

    - #### containsAll

          public boolean containsAll(Collection c)

      Specified by:
        `containsAll` in interface `Collection<E>`
      Specified by:
        `containsAll` in interface `List<E>`

    - #### get

          public E get(int index)

      Get the element at the supplied index, creating it if there is no element at that index.
      Specified by:
        `get` in interface `List<E>`

    - #### indexOf

          public int indexOf(Object o)

      Specified by:
        `indexOf` in interface `List<E>`

    - #### isEmpty

          public boolean isEmpty()

      Specified by:
        `isEmpty` in interface `Collection<E>`
      Specified by:
        `isEmpty` in interface `List<E>`

    - #### iterator

          public Iterator<E> iterator()

      Specified by:
        `iterator` in interface `Iterable<E>`
      Specified by:
        `iterator` in interface `Collection<E>`
      Specified by:
        `iterator` in interface `List<E>`

    - #### lastIndexOf

          public int lastIndexOf(Object o)

      Specified by:
        `lastIndexOf` in interface `List<E>`

    - #### listIterator

          public ListIterator<E> listIterator()

      Specified by:
        `listIterator` in interface `List<E>`

    - #### listIterator

          public ListIterator<E> listIterator(int index)

      Specified by:
        `listIterator` in interface `List<E>`

    - #### remove

          public E remove(int index)

      Specified by:
        `remove` in interface `List<E>`

    - #### remove

          public boolean remove(Object o)

      Specified by:
        `remove` in interface `Collection<E>`
      Specified by:
        `remove` in interface `List<E>`

    - #### removeAll

          public boolean removeAll(Collection<?> c)

      Specified by:
        `removeAll` in interface `Collection<E>`
      Specified by:
        `removeAll` in interface `List<E>`

    - #### retainAll

          public boolean retainAll(Collection<?> c)

      Specified by:
        `retainAll` in interface `Collection<E>`
      Specified by:
        `retainAll` in interface `List<E>`

    - #### set

          public E set(int index,
              E element)

      Specified by:
        `set` in interface `List<E>`

    - #### size

          public int size()

      Specified by:
        `size` in interface `Collection<E>`
      Specified by:
        `size` in interface `List<E>`

    - #### subList

          public List<E> subList(int fromIndex,
                        int toIndex)

      Specified by:
        `subList` in interface `List<E>`

    - #### toArray

          public Object[] toArray()

      Specified by:
        `toArray` in interface `Collection<E>`
      Specified by:
        `toArray` in interface `List<E>`

    - #### toArray

          public <T> T[] toArray(T[] a)

      Specified by:
        `toArray` in interface `Collection<E>`
      Specified by:
        `toArray` in interface `List<E>`

    - #### equals

          public boolean equals(Object other)

      Specified by:
        `equals` in interface `Collection<E>`
      Specified by:
        `equals` in interface `List<E>`
      Overrides:
        `equals` in class `Object`

    - #### hashCode

          public int hashCode()

      Specified by:
        `hashCode` in interface `Collection<E>`
      Specified by:
        `hashCode` in interface `List<E>`
      Overrides:
        `hashCode` in class `Object`