cursorablelinkedlist.java

初级java程序员如果想要更深一步提高自己的实力

            }
        }
    }

    public class Cursor extends ListIter implements ListIterator {
        boolean _valid = false;

        Cursor(int index) {
            super(index);
            _valid = true;
            registerCursor(this);
        }

        public int previousIndex() {
            throw new UnsupportedOperationException();
        }

        public int nextIndex() {
            throw new UnsupportedOperationException();
        }

        public void add(Object o) {
            checkForComod();
            Listable elt = insertListable(_cur.prev(),_cur.next(),o);
            _cur.setPrev(elt);
            _cur.setNext(elt.next());
            _lastReturned = null;
            _nextIndex++;
            _expectedModCount++;
        }

        protected void listableRemoved(Listable elt) {
            if(null == _head.prev()) {
                _cur.setNext(null);
            } else if(_cur.next() == elt) {
                _cur.setNext(elt.next());
            }
            if(null == _head.next()) {
                _cur.setPrev(null);
            } else if(_cur.prev() == elt) {
                _cur.setPrev(elt.prev());
            }
            if(_lastReturned == elt) {
                _lastReturned = null;
            }
        }

        protected void listableInserted(Listable elt) {
            if(null == _cur.next() && null == _cur.prev()) {
                _cur.setNext(elt);
            } else if(_cur.prev() == elt.prev()) {
                _cur.setNext(elt);
            }
            if(_cur.next() == elt.next()) {
                _cur.setPrev(elt);
            }
            if(_lastReturned == elt) {
                _lastReturned = null;
            }
        }

        protected void listableChanged(Listable elt) {
            if(_lastReturned == elt) {
                _lastReturned = null;
            }
        }

        protected void checkForComod() {
            if(!_valid) {
                throw new ConcurrentModificationException();
            }
        }

        protected void invalidate() {
            _valid = false;
        }

        /**
         * Mark this cursor as no longer being needed. Any resources
         * associated with this cursor are immediately released.
         * In previous versions of this class, it was mandatory to close
         * all cursor objects to avoid memory leaks. It is <i>no longer</i>
         * necessary to call this close method; an instance of this class
         * can now be treated exactly like a normal iterator.
         */
        public void close() {
            if(_valid) {
                _valid = false;
                unregisterCursor(this);
            }
        }
    }

}

/**
 * @deprecated Use new version in list subpackage, which has been rewritten
 *  and now returns the cursor from the listIterator method. Will be removed in v4.0
 */
class CursorableSubList extends CursorableLinkedList implements List {

    //--- constructors -----------------------------------------------

    CursorableSubList(CursorableLinkedList list, int from, int to) {
        if(0 > from || list.size() < to) {
            throw new IndexOutOfBoundsException();
        } else if(from > to) {
            throw new IllegalArgumentException();
        }
        _list = list;
        if(from < list.size()) {
            _head.setNext(_list.getListableAt(from));
            _pre = (null == _head.next()) ? null : _head.next().prev();
        } else {
            _pre = _list.getListableAt(from-1);
        }
        if(from == to) {
            _head.setNext(null);
            _head.setPrev(null);
            if(to < list.size()) {
                _post = _list.getListableAt(to);
            } else {
                _post = null;
            }
        } else {
            _head.setPrev(_list.getListableAt(to-1));
            _post = _head.prev().next();
        }
        _size = to - from;
        _modCount = _list._modCount;
    }

    //--- public methods ------------------------------------------

    public void clear() {
        checkForComod();
        Iterator it = iterator();
        while(it.hasNext()) {
            it.next();
            it.remove();
        }
    }

    public Iterator iterator() {
        checkForComod();
        return super.iterator();
    }

    public int size() {
        checkForComod();
        return super.size();
    }

    public boolean isEmpty() {
        checkForComod();
        return super.isEmpty();
    }

    public Object[] toArray() {
        checkForComod();
        return super.toArray();
    }

    public Object[] toArray(Object a[]) {
        checkForComod();
        return super.toArray(a);
    }

    public boolean contains(Object o) {
        checkForComod();
        return super.contains(o);
    }

    public boolean remove(Object o) {
        checkForComod();
        return super.remove(o);
    }

    public Object removeFirst() {
        checkForComod();
        return super.removeFirst();
    }

    public Object removeLast() {
        checkForComod();
        return super.removeLast();
    }

    public boolean addAll(Collection c) {
        checkForComod();
        return super.addAll(c);
    }

    public boolean add(Object o) {
        checkForComod();
        return super.add(o);
    }

    public boolean addFirst(Object o) {
        checkForComod();
        return super.addFirst(o);
    }

    public boolean addLast(Object o) {
        checkForComod();
        return super.addLast(o);
    }

    public boolean removeAll(Collection c) {
        checkForComod();
        return super.removeAll(c);
    }

    public boolean containsAll(Collection c) {
        checkForComod();
        return super.containsAll(c);
    }

    public boolean addAll(int index, Collection c) {
        checkForComod();
        return super.addAll(index,c);
    }

    public int hashCode() {
        checkForComod();
        return super.hashCode();
    }

    public boolean retainAll(Collection c) {
        checkForComod();
        return super.retainAll(c);
    }

    public Object set(int index, Object element) {
        checkForComod();
        return super.set(index,element);
    }

    public boolean equals(Object o) {
        checkForComod();
        return super.equals(o);
    }

    public Object get(int index) {
        checkForComod();
        return super.get(index);
    }

    public Object getFirst() {
        checkForComod();
        return super.getFirst();
    }

    public Object getLast() {
        checkForComod();
        return super.getLast();
    }

    public void add(int index, Object element) {
        checkForComod();
        super.add(index,element);
    }

    public ListIterator listIterator(int index) {
        checkForComod();
        return super.listIterator(index);
    }

    public Object remove(int index) {
        checkForComod();
        return super.remove(index);
    }

    public int indexOf(Object o) {
        checkForComod();
        return super.indexOf(o);
    }

    public int lastIndexOf(Object o) {
        checkForComod();
        return super.lastIndexOf(o);
    }

    public ListIterator listIterator() {
        checkForComod();
        return super.listIterator();
    }

    public List subList(int fromIndex, int toIndex) {
        checkForComod();
        return super.subList(fromIndex,toIndex);
    }

    //--- protected methods ------------------------------------------

    /**
     * Inserts a new <i>value</i> into my
     * list, after the specified <i>before</i> element, and before the
     * specified <i>after</i> element
     *
     * @return the newly created {@link CursorableLinkedList.Listable}
     */
    protected Listable insertListable(Listable before, Listable after, Object value) {
        _modCount++;
        _size++;
        Listable elt = _list.insertListable((null == before ? _pre : before), (null == after ? _post : after),value);
        if(null == _head.next()) {
            _head.setNext(elt);
            _head.setPrev(elt);
        }
        if(before == _head.prev()) {
            _head.setPrev(elt);
        }
        if(after == _head.next()) {
            _head.setNext(elt);
        }
        broadcastListableInserted(elt);
        return elt;
    }

    /**
     * Removes the given {@link CursorableLinkedList.Listable} from my list.
     */
    protected void removeListable(Listable elt) {
        _modCount++;
        _size--;
        if(_head.next() == elt && _head.prev() == elt) {
            _head.setNext(null);
            _head.setPrev(null);
        }
        if(_head.next() == elt) {
            _head.setNext(elt.next());
        }
        if(_head.prev() == elt) {
            _head.setPrev(elt.prev());
        }
        _list.removeListable(elt);
        broadcastListableRemoved(elt);
    }

    /**
     * Test to see if my underlying list has been modified
     * by some other process.  If it has, throws a
     * {@link ConcurrentModificationException}, otherwise
     * quietly returns.
     *
     * @throws ConcurrentModificationException
     */
    protected void checkForComod() throws ConcurrentModificationException {
        if(_modCount != _list._modCount) {
            throw new ConcurrentModificationException();
        }
    }

    //--- protected attributes ---------------------------------------

    /** My underlying list */
    protected CursorableLinkedList _list = null;

    /** The element in my underlying list preceding the first element in my list. */
    protected Listable _pre = null;

    /** The element in my underlying list following the last element in my list. */
    protected Listable _post = null;

}