Package org.apache.commons.collections4.list

Class GrowthList<E>

  • All Implemented Interfaces:
    Serializable, Iterable<E>, Collection<E>, List<E>
    public class GrowthList<E>
extends AbstractSerializableListDecorator<E>
    Decorates another List to make it seamlessly grow when indices larger than the list size are used on add and set, avoiding most IndexOutOfBoundsExceptions.

    This class avoids errors by growing when a set or add method would normally throw an IndexOutOfBoundsException. Note that IndexOutOfBoundsException IS returned for invalid negative indices.

    Trying to set or add to an index larger than the size will cause the list to grow (using null elements). Clearly, care must be taken not to use excessively large indices, as the internal list will grow to match.

    Trying to use any method other than add or set with an invalid index will call the underlying list and probably result in an IndexOutOfBoundsException.

    Take care when using this list with null values, as null is the value added when growing the list.

    All sub-lists will access the underlying list directly, and will throw IndexOutOfBoundsExceptions.

    This class differs from LazyList because here growth occurs on set and add, where LazyList grows on get. However, they can be used together by decorating twice.

    Since:
    3.2
    See Also:
    LazyList, Serialized Form

    • Constructor Detail

      • GrowthList

        public GrowthList()
        Constructor that uses an ArrayList internally.

      • GrowthList

        public GrowthList​(int initialSize)
        Constructor that uses an ArrayList internally.
        Parameters:
        initialSize - the initial size of the ArrayList
        Throws:
        IllegalArgumentException - if initial size is invalid

      • GrowthList

        protected GrowthList​(List<E> list)
        Constructor that wraps (not copies).
        Parameters:
        list - the list to decorate, must not be null
        Throws:
        NullPointerException - if list is null

    • Method Detail

      • growthList

        public static <E> GrowthList<E> growthList​(List<E> list)
        Factory method to create a growth list.
        Type Parameters:
        E - the type of the elements in the list
        Parameters:
        list - the list to decorate, must not be null
        Returns:
        a new growth list
        Throws:
        NullPointerException - if list is null
        Since:
        4.0

      • add

        public void add​(int index,
                E element)
        Decorate the add method to perform the growth behaviour.

        If the requested index is greater than the current size, the list will grow to the new size. Indices between the old size and the requested size will be filled with null.

        If the index is less than the current size, the value will be added to the underlying list directly. If the index is less than zero, the underlying list is called, which will probably throw an IndexOutOfBoundsException.

        Specified by:
        add in interface List<E>
        Overrides:
        add in class AbstractListDecorator<E>
        Parameters:
        index - the index to add at
        element - the object to add at the specified index
        Throws:
        UnsupportedOperationException - if the underlying list doesn't implement set
        ClassCastException - if the underlying list rejects the element
        IllegalArgumentException - if the underlying list rejects the element

      • addAll

        public boolean addAll​(int index,
                      Collection<? extends E> coll)
        Decorate the addAll method to perform the growth behaviour.

        If the requested index is greater than the current size, the list will grow to the new size. Indices between the old size and the requested size will be filled with null.

        If the index is less than the current size, the values will be added to the underlying list directly. If the index is less than zero, the underlying list is called, which will probably throw an IndexOutOfBoundsException.

        Specified by:
        addAll in interface List<E>
        Overrides:
        addAll in class AbstractListDecorator<E>
        Parameters:
        index - the index to add at
        coll - the collection to add at the specified index
        Returns:
        true if the list changed
        Throws:
        UnsupportedOperationException - if the underlying list doesn't implement set
        ClassCastException - if the underlying list rejects the element
        IllegalArgumentException - if the underlying list rejects the element

      • set

        public E set​(int index,
             E element)
        Decorate the set method to perform the growth behaviour.

        If the requested index is greater than the current size, the list will grow to the new size. Indices between the old size and the requested size will be filled with null.

        If the index is less than the current size, the value will be set onto the underlying list directly. If the index is less than zero, the underlying list is called, which will probably throw an IndexOutOfBoundsException.

        Specified by:
        set in interface List<E>
        Overrides:
        set in class AbstractListDecorator<E>
        Parameters:
        index - the index to set
        element - the object to set at the specified index
        Returns:
        the object previously at that index
        Throws:
        UnsupportedOperationException - if the underlying list doesn't implement set
        ClassCastException - if the underlying list rejects the element
        IllegalArgumentException - if the underlying list rejects the element