abstractlinkedlist.java

JAVA 文章管理系统源码

        }
        ListIterator it1 = listIterator();
        ListIterator it2 = other.listIterator();
        while (it1.hasNext() && it2.hasNext()) {
            Object o1 = it1.next();
            Object o2 = it2.next();
            if (!(o1 == null ? o2 == null : o1.equals(o2)))
                return false;
        }
        return !(it1.hasNext() || it2.hasNext());
    }

    public int hashCode() {
        int hashCode = 1;
        Iterator it = iterator();
        while (it.hasNext()) {
            Object obj = it.next();
            hashCode = 31 * hashCode + (obj == null ? 0 : obj.hashCode());
        }
        return hashCode;
    }

    public String toString() {
        if (size() == 0) {
            return "[]";
        }
        StringBuffer buf = new StringBuffer(16 * size());
        buf.append("[");

        Iterator it = iterator();
        boolean hasNext = it.hasNext();
        while (hasNext) {
            Object value = it.next();
            buf.append(value == this ? "(this Collection)" : value);
            hasNext = it.hasNext();
            if (hasNext) {
                buf.append(", ");
            }
        }
        buf.append("]");
        return buf.toString();
    }

    //-----------------------------------------------------------------------
    /**
     * Compares two values for equals.
     * This implementation uses the equals method.
     * Subclasses can override this to match differently.
     * 
     * @param value1  the first value to compare, may be null
     * @param value2  the second value to compare, may be null
     * @return true if equal
     */
    protected boolean isEqualValue(Object value1, Object value2) {
        return (value1 == value2 || (value1 == null ? false : value1.equals(value2)));
    }
    
    /**
     * Updates the node with a new value.
     * This implementation sets the value on the node.
     * Subclasses can override this to record the change.
     * 
     * @param node  node to update
     * @param value  new value of the node
     */
    protected void updateNode(Node node, Object value) {
        node.setValue(value);
    }

    /**
     * Creates a new node with previous, next and element all set to null.
     * This implementation creates a new empty Node.
     * Subclasses can override this to create a different class.
     * 
     * @return  newly created node
     */
    protected Node createHeaderNode() {
        return new Node();
    }

    /**
     * Creates a new node with the specified properties.
     * This implementation creates a new Node with data.
     * Subclasses can override this to create a different class.
     * 
     * @param value  value of the new node
     */
    protected Node createNode(Object value) {
        return new Node(value);
    }

    /**
     * Creates a new node with the specified object as its 
     * <code>value</code> and inserts it before <code>node</code>.
     * <p>
     * This implementation uses {@link #createNode(Object)} and
     * {@link #addNode(AbstractLinkedList.Node,AbstractLinkedList.Node)}.
     *
     * @param node  node to insert before
     * @param value  value of the newly added node
     * @throws NullPointerException if <code>node</code> is null
     */
    protected void addNodeBefore(Node node, Object value) {
        Node newNode = createNode(value);
        addNode(newNode, node);
    }

    /**
     * Creates a new node with the specified object as its 
     * <code>value</code> and inserts it after <code>node</code>.
     * <p>
     * This implementation uses {@link #createNode(Object)} and
     * {@link #addNode(AbstractLinkedList.Node,AbstractLinkedList.Node)}.
     * 
     * @param node  node to insert after
     * @param value  value of the newly added node
     * @throws NullPointerException if <code>node</code> is null
     */
    protected void addNodeAfter(Node node, Object value) {
        Node newNode = createNode(value);
        addNode(newNode, node.next);
    }

    /**
     * Inserts a new node into the list.
     *
     * @param nodeToInsert  new node to insert
     * @param insertBeforeNode  node to insert before
     * @throws NullPointerException if either node is null
     */
    protected void addNode(Node nodeToInsert, Node insertBeforeNode) {
        nodeToInsert.next = insertBeforeNode;
        nodeToInsert.previous = insertBeforeNode.previous;
        insertBeforeNode.previous.next = nodeToInsert;
        insertBeforeNode.previous = nodeToInsert;
        size++;
        modCount++;
    }

    /**
     * Removes the specified node from the list.
     *
     * @param node  the node to remove
     * @throws NullPointerException if <code>node</code> is null
     */
    protected void removeNode(Node node) {
        node.previous.next = node.next;
        node.next.previous = node.previous;
        size--;
        modCount++;
    }

    /**
     * Removes all nodes by resetting the circular list marker.
     */
    protected void removeAllNodes() {
        header.next = header;
        header.previous = header;
        size = 0;
        modCount++;
    }

    /**
     * Gets the node at a particular index.
     * 
     * @param index  the index, starting from 0
     * @param endMarkerAllowed  whether or not the end marker can be returned if
     * startIndex is set to the list's size
     * @throws IndexOutOfBoundsException if the index is less than 0; equal to
     * the size of the list and endMakerAllowed is false; or greater than the
     * size of the list
     */
    protected Node getNode(int index, boolean endMarkerAllowed) throws IndexOutOfBoundsException {
        // Check the index is within the bounds
        if (index < 0) {
            throw new IndexOutOfBoundsException("Couldn't get the node: " +
                    "index (" + index + ") less than zero.");
        }
        if (!endMarkerAllowed && index == size) {
            throw new IndexOutOfBoundsException("Couldn't get the node: " +
                    "index (" + index + ") is the size of the list.");
        }
        if (index > size) {
            throw new IndexOutOfBoundsException("Couldn't get the node: " +
                    "index (" + index + ") greater than the size of the " +
                    "list (" + size + ").");
        }
        // Search the list and get the node
        Node node;
        if (index < (size / 2)) {
            // Search forwards
            node = header.next;
            for (int currentIndex = 0; currentIndex < index; currentIndex++) {
                node = node.next;
            }
        } else {
            // Search backwards
            node = header;
            for (int currentIndex = size; currentIndex > index; currentIndex--) {
                node = node.previous;
            }
        }
        return node;
    }

    //-----------------------------------------------------------------------
    /**
     * Creates an iterator for the sublist.
     * 
     * @param subList  the sublist to get an iterator for
     */
    protected Iterator createSubListIterator(LinkedSubList subList) {
        return createSubListListIterator(subList, 0);
    }

    /**
     * Creates a list iterator for the sublist.
     * 
     * @param subList  the sublist to get an iterator for
     * @param fromIndex  the index to start from, relative to the sublist
     */
    protected ListIterator createSubListListIterator(LinkedSubList subList, int fromIndex) {
        return new LinkedSubListIterator(subList, fromIndex);
    }

    //-----------------------------------------------------------------------
    /**
     * Serializes the data held in this object to the stream specified.
     * <p>
     * The first serializable subclass must call this method from
     * <code>writeObject</code>.
     */
    protected void doWriteObject(ObjectOutputStream outputStream) throws IOException {
        // Write the size so we know how many nodes to read back
        outputStream.writeInt(size());
        for (Iterator itr = iterator(); itr.hasNext();) {
            outputStream.writeObject(itr.next());
        }
    }

    /**
     * Deserializes the data held in this object to the stream specified.
     * <p>
     * The first serializable subclass must call this method from
     * <code>readObject</code>.
     */
    protected void doReadObject(ObjectInputStream inputStream) throws IOException, ClassNotFoundException {
        init();
        int size = inputStream.readInt();
        for (int i = 0; i < size; i++) {
            add(inputStream.readObject());
        }
    }

    //-----------------------------------------------------------------------
    /**
     * A node within the linked list.
     * <p>
     * From Commons Collections 3.1, all access to the <code>value</code> property
     * is via the methods on this class.
     */
    protected static class Node {

        /** A pointer to the node before this node */
        protected Node previous;
        /** A pointer to the node after this node */
        protected Node next;
        /** The object contained within this node */
        protected Object value;

        /**
         * Constructs a new header node.
         */
        protected Node() {
            super();
            previous = this;
            next = this;
        }

        /**
         * Constructs a new node.
         * 
         * @param value  the value to store
         */
        protected Node(Object value) {
            super();
            this.value = value;
        }
        
        /**
         * Constructs a new node.
         * 
         * @param previous  the previous node in the list
         * @param next  the next node in the list
         * @param value  the value to store
         */
        protected Node(Node previous, Node next, Object value) {
            super();
            this.previous = previous;
            this.next = next;
            this.value = value;
        }
        
        /**
         * Gets the value of the node.
         * 
         * @return the value
         * @since Commons Collections 3.1
         */
        protected Object getValue() {
            return value;
        }
        
        /**
         * Sets the value of the node.
         * 
         * @param value  the value
         * @since Commons Collections 3.1
         */
        protected void setValue(Object value) {
            this.value = value;
        }
        
        /**
         * Gets the previous node.
         * 
         * @return the previous node
         * @since Commons Collections 3.1
         */
        protected Node getPreviousNode() {
            return previous;
        }
        
        /**
         * Sets the previous node.