Package com.google.common.collect

Class ForwardingCollection<E>

  • All Implemented Interfaces:
    java.lang.Iterable<E>, java.util.Collection<E>
    Direct Known Subclasses:
    ForwardingList, ForwardingMultiset, ForwardingQueue, ForwardingSet
    @GwtCompatible
public abstract class ForwardingCollection<E>
extends ForwardingObject
implements java.util.Collection<E>
    A collection which forwards all its method calls to another collection. Subclasses should override one or more methods to modify the behavior of the backing collection as desired per the decorator pattern.

    Warning: The methods of ForwardingCollection forward indiscriminately to the methods of the delegate. For example, overriding add(E) alone will not change the behavior of addAll(java.util.Collection<? extends E>), which can lead to unexpected behavior. In this case, you should override addAll as well, either providing your own implementation, or delegating to the provided standardAddAll method.

    The standard methods are not guaranteed to be thread-safe, even when all of the methods that they depend on are thread-safe.

    Since:
    2.0 (imported from Google Collections Library)

    • Constructor Detail

      • ForwardingCollection

        protected ForwardingCollection()
        Constructor for use by subclasses.

    • Method Detail

      • delegate

        protected abstract java.util.Collection<E> delegate()
        Description copied from class: ForwardingObject
        Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such as ForwardingSet.delegate(). Concrete subclasses override this method to supply the instance being decorated.
        Specified by:
        delegate in class ForwardingObject

      • iterator

        public java.util.Iterator<E> iterator()
        Specified by:
        iterator in interface java.util.Collection<E>
        Specified by:
        iterator in interface java.lang.Iterable<E>

      • size

        public int size()
        Specified by:
        size in interface java.util.Collection<E>

      • removeAll

        public boolean removeAll​(java.util.Collection<?> collection)
        Specified by:
        removeAll in interface java.util.Collection<E>

      • isEmpty

        public boolean isEmpty()
        Specified by:
        isEmpty in interface java.util.Collection<E>

      • contains

        public boolean contains​(java.lang.Object object)
        Specified by:
        contains in interface java.util.Collection<E>

      • add

        public boolean add​(E element)
        Specified by:
        add in interface java.util.Collection<E>

      • remove

        public boolean remove​(java.lang.Object object)
        Specified by:
        remove in interface java.util.Collection<E>

      • containsAll

        public boolean containsAll​(java.util.Collection<?> collection)
        Specified by:
        containsAll in interface java.util.Collection<E>

      • addAll

        public boolean addAll​(java.util.Collection<? extends E> collection)
        Specified by:
        addAll in interface java.util.Collection<E>

      • retainAll

        public boolean retainAll​(java.util.Collection<?> collection)
        Specified by:
        retainAll in interface java.util.Collection<E>

      • clear

        public void clear()
        Specified by:
        clear in interface java.util.Collection<E>

      • toArray

        public java.lang.Object[] toArray()
        Specified by:
        toArray in interface java.util.Collection<E>

      • toArray

        public <T> T[] toArray​(T[] array)
        Specified by:
        toArray in interface java.util.Collection<E>

      • standardClear

        protected void standardClear()
        A sensible definition of clear() in terms of iterator(), using the iterator's remove method. If you override iterator(), you may wish to override clear() to forward to this implementation.
        Since:
        7.0

      • standardIsEmpty

        protected boolean standardIsEmpty()
        A sensible definition of isEmpty() as !iterator().hasNext. If you override isEmpty(), you may wish to override isEmpty() to forward to this implementation. Alternately, it may be more efficient to implement isEmpty as size() == 0.
        Since:
        7.0

      • standardToArray

        protected <T> T[] standardToArray​(T[] array)
        A sensible definition of toArray(Object[]) in terms of size() and iterator(). If you override either of these methods, you may wish to override toArray() to forward to this implementation.
        Since:
        7.0