Class LazyList<E>
- Type Parameters:
- E- the type of the elements in the list.
- All Implemented Interfaces:
- Serializable,- Iterable<E>,- Collection<E>,- List<E>
List to create objects in the list on demand.
 
 When the get(int) method is called with an index greater than
 the size of the list, the list will automatically grow in size and return
 a new object from the specified factory or transformer. The gaps will be
 filled by null. If a get method call encounters a null, it will be replaced
 with a new object from the factory. Thus this list is unsuitable for
 storing null objects.
 
For instance:
 Factory<Date> factory = new Factory<Date>() {
     public Date create() {
         return new Date();
     }
 }
 List<Date> lazy = LazyList.decorate(new ArrayList<Date>(), factory);
 Date date = lazy.get(3);
 
 
 After the above code is executed, date will contain
 a new Date instance.  Furthermore, that Date
 instance is the fourth element in the list.  The first, second,
 and third element are all set to null.
 
 This class differs from GrowthList because here growth occurs on
 get, where GrowthList grows on set and add. However, they
 could easily be used together by decorating twice.
 
This class is Serializable from Commons Collections 3.1.
- Since:
- 3.0
- See Also:
- 
Constructor SummaryConstructors
- 
Method SummaryModifier and TypeMethodDescriptionget(int index) Decorate the get method to perform the lazy behavior.static <E> LazyList<E> Factory method to create a lazily instantiating list.static <E> LazyList<E> lazyList(List<E> list, Transformer<Integer, ? extends E> transformer) Transformer method to create a lazily instantiating list.subList(int fromIndex, int toIndex) Methods inherited from class org.apache.commons.collections4.list.AbstractListDecoratoradd, addAll, decorated, equals, hashCode, indexOf, lastIndexOf, listIterator, listIterator, remove, setMethods inherited from class org.apache.commons.collections4.collection.AbstractCollectionDecoratoradd, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, removeIf, retainAll, setCollection, size, toArray, toArray, toStringMethods inherited from class java.lang.Objectclone, finalize, getClass, notify, notifyAll, wait, wait, waitMethods inherited from interface java.util.CollectionparallelStream, removeIf, stream
- 
Constructor Details- 
LazyList
- 
LazyListConstructor that wraps (not copies).- Parameters:
- list- the list to decorate, must not be null
- transformer- the transformer to use for creation, must not be null
- Throws:
- NullPointerException- if list or transformer is null
 
 
- 
- 
Method Details- 
lazyListFactory method to create a lazily instantiating list.- Type Parameters:
- E- the type of the elements in the list
- Parameters:
- list- the list to decorate, must not be null
- factory- the factory to use for creation, must not be null
- Returns:
- a new lazy list
- Throws:
- NullPointerException- if list or factory is null
- Since:
- 4.0
 
- 
lazyListTransformer method to create a lazily instantiating list.- Type Parameters:
- E- the type of the elements in the list
- Parameters:
- list- the list to decorate, must not be null
- transformer- the transformer to use for creation, must not be null
- Returns:
- a new lazy list
- Throws:
- NullPointerException- if list or transformer is null
- Since:
- 4.4
 
- 
getDecorate the get method to perform the lazy behavior.If the requested index is greater than the current size, the list will grow to the new size and a new object will be returned from the factory or transformer. Indexes in-between the old size and the requested size are left with a placeholder that is replaced with a factory or transformer object when requested. 
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subList
 
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