Class ForwardingCollection<E extends @Nullable java.lang.Object>

  • 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 @Nullable java.lang.Object>
    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.

    default method warning: This class does not forward calls to default methods. Instead, it inherits their default implementations. When those implementations invoke methods, they invoke methods on the ForwardingCollection.

    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
    Author:
    Kevin Bourrillion, Louis Wasserman
    • Constructor Detail

    • Method Detail

      • delegate

        protected abstract java.util.Collection<Edelegate()
        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<Eiterator()
        Specified by:
        iterator in interface java.util.Collection<E extends @Nullable java.lang.Object>
        Specified by:
        iterator in interface java.lang.Iterable<E extends @Nullable java.lang.Object>
      • size

        public int size()
        Specified by:
        size in interface java.util.Collection<E extends @Nullable java.lang.Object>
      • removeAll

        @CanIgnoreReturnValue
        public boolean removeAll​(java.util.Collection<?> collection)
        Specified by:
        removeAll in interface java.util.Collection<E extends @Nullable java.lang.Object>
      • isEmpty

        public boolean isEmpty()
        Specified by:
        isEmpty in interface java.util.Collection<E extends @Nullable java.lang.Object>
      • contains

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

        @CanIgnoreReturnValue
        public boolean add​(E element)
        Specified by:
        add in interface java.util.Collection<E extends @Nullable java.lang.Object>
      • remove

        @CanIgnoreReturnValue
        public boolean remove​(@Nullable java.lang.Object object)
        Specified by:
        remove in interface java.util.Collection<E extends @Nullable java.lang.Object>
      • containsAll

        public boolean containsAll​(java.util.Collection<?> collection)
        Specified by:
        containsAll in interface java.util.Collection<E extends @Nullable java.lang.Object>
      • addAll

        @CanIgnoreReturnValue
        public boolean addAll​(java.util.Collection<? extends E> collection)
        Specified by:
        addAll in interface java.util.Collection<E extends @Nullable java.lang.Object>
      • retainAll

        @CanIgnoreReturnValue
        public boolean retainAll​(java.util.Collection<?> collection)
        Specified by:
        retainAll in interface java.util.Collection<E extends @Nullable java.lang.Object>
      • clear

        public void clear()
        Specified by:
        clear in interface java.util.Collection<E extends @Nullable java.lang.Object>
      • toArray

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

        @CanIgnoreReturnValue
        public <T extends @Nullable java.lang.Object> T[] toArray​(T[] array)
        Specified by:
        toArray in interface java.util.Collection<E extends @Nullable java.lang.Object>
      • 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 extends @Nullable java.lang.Object> 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