src/main/java/org/apache/commons/collections4/list/AbstractLinkedList.java [109:215]:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                throws IndexOutOfBoundsException {
            this.parent = parent;
            this.expectedModCount = parent.modCount;
            this.next = parent.getNode(fromIndex, true);
            this.nextIndex = fromIndex;
        }

        @Override
        public void add(final E obj) {
            checkModCount();
            parent.addNodeBefore(next, obj);
            current = null;
            nextIndex++;
            expectedModCount++;
        }

        /**
         * Checks the modification count of the list is the value that this
         * object expects.
         *
         * @throws ConcurrentModificationException If the list's modification
         * count isn't the value that was expected.
         */
        protected void checkModCount() {
            if (parent.modCount != expectedModCount) {
                throw new ConcurrentModificationException();
            }
        }

        /**
         * Gets the last node returned.
         *
         * @return the last node returned
         * @throws IllegalStateException If {@link #next()} or {@link #previous()} haven't been called,
         * or if the node has been removed with {@link #remove()} or a new node added with {@link #add(Object)}.
         */
        protected Node<E> getLastNodeReturned() throws IllegalStateException {
            if (current == null) {
                throw new IllegalStateException();
            }
            return current;
        }

        @Override
        public boolean hasNext() {
            return next != parent.header;
        }

        @Override
        public boolean hasPrevious() {
            return next.previous != parent.header;
        }

        @Override
        public E next() {
            checkModCount();
            if (!hasNext()) {
                throw new NoSuchElementException("No element at index " + nextIndex + ".");
            }
            final E value = next.getValue();
            current = next;
            next = next.next;
            nextIndex++;
            return value;
        }

        @Override
        public int nextIndex() {
            return nextIndex;
        }

        @Override
        public E previous() {
            checkModCount();
            if (!hasPrevious()) {
                throw new NoSuchElementException("Already at start of list.");
            }
            next = next.previous;
            final E value = next.getValue();
            current = next;
            nextIndex--;
            return value;
        }

        @Override
        public int previousIndex() {
            // not normally overridden, as relative to nextIndex()
            return nextIndex() - 1;
        }

        @Override
        public void remove() {
            checkModCount();
            if (current == next) {
                // remove() following previous()
                next = next.next;
                parent.removeNode(getLastNodeReturned());
            } else {
                // remove() following next()
                parent.removeNode(getLastNodeReturned());
                nextIndex--;
            }
            current = null;
            expectedModCount++;
        }

        @Override
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -



src/main/java/org/apache/commons/collections4/list/AbstractLinkedListJava21.java [112:218]:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                throws IndexOutOfBoundsException {
            this.parent = parent;
            this.expectedModCount = parent.modCount;
            this.next = parent.getNode(fromIndex, true);
            this.nextIndex = fromIndex;
        }

        @Override
        public void add(final E obj) {
            checkModCount();
            parent.addNodeBefore(next, obj);
            current = null;
            nextIndex++;
            expectedModCount++;
        }

        /**
         * Checks the modification count of the list is the value that this
         * object expects.
         *
         * @throws ConcurrentModificationException If the list's modification
         * count isn't the value that was expected.
         */
        protected void checkModCount() {
            if (parent.modCount != expectedModCount) {
                throw new ConcurrentModificationException();
            }
        }

        /**
         * Gets the last node returned.
         *
         * @return the last node returned
         * @throws IllegalStateException If {@link #next()} or {@link #previous()} haven't been called,
         * or if the node has been removed with {@link #remove()} or a new node added with {@link #add(Object)}.
         */
        protected Node<E> getLastNodeReturned() throws IllegalStateException {
            if (current == null) {
                throw new IllegalStateException();
            }
            return current;
        }

        @Override
        public boolean hasNext() {
            return next != parent.header;
        }

        @Override
        public boolean hasPrevious() {
            return next.previous != parent.header;
        }

        @Override
        public E next() {
            checkModCount();
            if (!hasNext()) {
                throw new NoSuchElementException("No element at index " + nextIndex + ".");
            }
            final E value = next.getValue();
            current = next;
            next = next.next;
            nextIndex++;
            return value;
        }

        @Override
        public int nextIndex() {
            return nextIndex;
        }

        @Override
        public E previous() {
            checkModCount();
            if (!hasPrevious()) {
                throw new NoSuchElementException("Already at start of list.");
            }
            next = next.previous;
            final E value = next.getValue();
            current = next;
            nextIndex--;
            return value;
        }

        @Override
        public int previousIndex() {
            // not normally overridden, as relative to nextIndex()
            return nextIndex() - 1;
        }

        @Override
        public void remove() {
            checkModCount();
            if (current == next) {
                // remove() following previous()
                next = next.next;
                parent.removeNode(getLastNodeReturned());
            } else {
                // remove() following next()
                parent.removeNode(getLastNodeReturned());
                nextIndex--;
            }
            current = null;
            expectedModCount++;
        }

        @Override
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -