linkedlist.java

This is a resource based on j2me embedded,if you dont understand,you can connection with me .

     * @throws IndexOutOfBoundsException if the specified index is out of
     * 		  range (<tt>index &lt; 0 || index &gt;= size()</tt>).
     */
    public Object remove(int index) {
        Entry e = entry(index);
        remove(e);
        return e.element;
    }

    /**
     * Return the indexed entry.
     */
    private Entry entry(int index) {
        if (index < 0 || index >= size)
            throw new IndexOutOfBoundsException("Index: "+index+
                                                ", Size: "+size);
        Entry e = header;
        if (index < (size >> 1)) {
            for (int i = 0; i <= index; i++)
                e = e.next;
        } else {
            for (int i = size; i > index; i--)
                e = e.previous;
        }
        return e;
    }


    // Search Operations

    /**
     * Returns the index in this list of the first occurrence of the
     * specified element, or -1 if the List does not contain this
     * element.  More formally, returns the lowest index i such that
     * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, or -1 if
     * there is no such index.
     *
     * @param o element to search for.
     * @return the index in this list of the first occurrence of the
     * 	       specified element, or -1 if the list does not contain this
     * 	       element.
     */
    public int indexOf(Object o) {
        int index = 0;
        if (o==null) {
            for (Entry e = header.next; e != header; e = e.next) {
                if (e.element==null)
                    return index;
                index++;
            }
        } else {
            for (Entry e = header.next; e != header; e = e.next) {
                if (o.equals(e.element))
                    return index;
                index++;
            }
        }
        return -1;
    }

    /**
     * Returns the index in this list of the last occurrence of the
     * specified element, or -1 if the list does not contain this
     * element.  More formally, returns the highest index i such that
     * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, or -1 if
     * there is no such index.
     *
     * @param o element to search for.
     * @return the index in this list of the last occurrence of the
     * 	       specified element, or -1 if the list does not contain this
     * 	       element.
     */
    public int lastIndexOf(Object o) {
        int index = size;
        if (o==null) {
            for (Entry e = header.previous; e != header; e = e.previous) {
                index--;
                if (e.element==null)
                    return index;
            }
        } else {
            for (Entry e = header.previous; e != header; e = e.previous) {
                index--;
                if (o.equals(e.element))
                    return index;
            }
        }
        return -1;
    }

    /**
     * Returns a list-iterator of the elements in this list (in proper
     * sequence), starting at the specified position in the list.
     * Obeys the general contract of <tt>List.listIterator(int)</tt>.<p>
     *
     * The list-iterator is <i>fail-fast</i>: if the list is structurally
     * modified at any time after the Iterator is created, in any way except
     * through the list-iterator's own <tt>remove</tt> or <tt>add</tt>
     * methods, the list-iterator will throw a
     * <tt>ConcurrentModificationException</tt>.  Thus, in the face of
     * concurrent modification, the iterator fails quickly and cleanly, rather
     * than risking arbitrary, non-deterministic behavior at an undetermined
     * time in the future.
     *
     * @param index index of first element to be returned from the
     *		    list-iterator (by a call to <tt>next</tt>).
     * @return a ListIterator of the elements in this list (in proper
     * 	       sequence), starting at the specified position in the list.
     * @throws    IndexOutOfBoundsException if index is out of range
     *		  (<tt>index &lt; 0 || index &gt; size()</tt>).
     * @see List#listIterator(int)
     */
    public ListIterator listIterator(int index) {
	return new ListItr(index);
    }

    private class ListItr implements ListIterator {
	private Entry lastReturned = header;
	private Entry next;
	private int nextIndex;
	private int expectedModCount = modCount;

	ListItr(int index) {
	    if (index < 0 || index > size)
		throw new IndexOutOfBoundsException("Index: "+index+
						    ", Size: "+size);
	    if (index < (size >> 1)) {
		next = header.next;
		for (nextIndex=0; nextIndex<index; nextIndex++)
		    next = next.next;
	    } else {
		next = header;
		for (nextIndex=size; nextIndex>index; nextIndex--)
		    next = next.previous;
	    }
	}

	public boolean hasNext() {
	    return nextIndex != size;
	}

	public Object next() {
	    checkForComodification();
	    if (nextIndex == size)
		throw new NoSuchElementException();

	    lastReturned = next;
	    next = next.next;
	    nextIndex++;
	    return lastReturned.element;
	}

	public boolean hasPrevious() {
	    return nextIndex != 0;
	}

	public Object previous() {
	    if (nextIndex == 0)
		throw new NoSuchElementException();

	    lastReturned = next = next.previous;
	    nextIndex--;
	    checkForComodification();
	    return lastReturned.element;
	}

	public int nextIndex() {
	    return nextIndex;
	}

	public int previousIndex() {
	    return nextIndex-1;
	}

	public void remove() {
            checkForComodification();
            try {
                LinkedList.this.remove(lastReturned);
            } catch (NoSuchElementException e) {
                throw new IllegalStateException();
            }
	    if (next==lastReturned)
                next = lastReturned.next;
            else
		nextIndex--;
	    lastReturned = header;
	    expectedModCount++;
	}

	public void set(Object o) {
	    if (lastReturned == header)
		throw new IllegalStateException();
	    checkForComodification();
	    lastReturned.element = o;
	}

	public void add(Object o) {
	    checkForComodification();
	    lastReturned = header;
	    addBefore(o, next);
	    nextIndex++;
	    expectedModCount++;
	}

	final void checkForComodification() {
	    if (modCount != expectedModCount)
		throw new ConcurrentModificationException();
	}
    }

    private static class Entry {
	Object element;
	Entry next;
	Entry previous;

	Entry(Object element, Entry next, Entry previous) {
	    this.element = element;
	    this.next = next;
	    this.previous = previous;
	}
    }

    private Entry addBefore(Object o, Entry e) {
	Entry newEntry = new Entry(o, e, e.previous);
	newEntry.previous.next = newEntry;
	newEntry.next.previous = newEntry;
	size++;
	modCount++;
	return newEntry;
    }

    private void remove(Entry e) {
	if (e == header)
	    throw new NoSuchElementException();

	e.previous.next = e.next;
	e.next.previous = e.previous;
	size--;
	modCount++;
    }

    /**
     * Returns a shallow copy of this <tt>LinkedList</tt>. (The elements
     * themselves are not cloned.)
     *
     * @return a shallow copy of this <tt>LinkedList</tt> instance.
     */
    public Object clone() {
        LinkedList clone = null;
	try { 
	    clone = (LinkedList)super.clone();
	} catch (CloneNotSupportedException e) { 
	    throw new InternalError();
	}

        // Put clone into "virgin" state
        clone.header = new Entry(null, null, null);
        clone.header.next = clone.header.previous = clone.header;
        clone.size = 0;
        clone.modCount = 0;

        // Initialize clone with our elements
        for (Entry e = header.next; e != header; e = e.next)
            clone.add(e.element);

        return clone;
    }

    /**
     * Returns an array containing all of the elements in this list
     * in the correct order.
     *
     * @return an array containing all of the elements in this list
     * 	       in the correct order.
     */
    public Object[] toArray() {
	Object[] result = new Object[size];
        int i = 0;
        for (Entry e = header.next; e != header; e = e.next)
            result[i++] = e.element;
	return result;
    }

    /**
     * Returns an array containing all of the elements in this list in
     * the correct order; the runtime type of the returned array is that of
     * the specified array.  If the list fits in the specified array, it
     * is returned therein.  Otherwise, a new array is allocated with the
     * runtime type of the specified array and the size of this list.<p>
     *
     * If the list fits in the specified array with room to spare
     * (i.e., the array has more elements than the list),
     * the element in the array immediately following the end of the
     * collection is set to null.  This is useful in determining the length
     * of the list <i>only</i> if the caller knows that the list
     * does not contain any null elements.
     *
     * @param a the array into which the elements of the list are to
     *		be stored, if it is big enough; otherwise, a new array of the
     * 		same runtime type is allocated for this purpose.
     * @return an array containing the elements of the list.
     * @throws ArrayStoreException if the runtime type of a is not a
     *         supertype of the runtime type of every element in this list.
     * @throws NullPointerException if the specified array is null.
     */
    public Object[] toArray(Object a[]) {
        if (a.length < size)
            a = (Object[])java.lang.reflect.Array.newInstance(
                                a.getClass().getComponentType(), size);
        int i = 0;
        for (Entry e = header.next; e != header; e = e.next)
            a[i++] = e.element;

        if (a.length > size)
            a[size] = null;

        return a;
    }

    private static final long serialVersionUID = 876323262645176354L;

    /**
     * Save the state of this <tt>LinkedList</tt> instance to a stream (that
     * is, serialize it).
     *
     * @serialData The size of the list (the number of elements it
     *		   contains) is emitted (int), followed by all of its
     * elements (each an Object) in the proper order.  
     */
    private void writeObject(java.io.ObjectOutputStream s)
        throws java.io.IOException {
	// Write out any hidden serialization magic
	s.defaultWriteObject();

        // Write out size
        s.writeInt(size);

	// Write out all elements in the proper order.
        for (Entry e = header.next; e != header; e = e.next)
            s.writeObject(e.element);
    }

    /**
     * Reconstitute this <tt>LinkedList</tt> instance from a stream (that is
     * deserialize it).
     */
    private void readObject(java.io.ObjectInputStream s)
        throws java.io.IOException, ClassNotFoundException {
	// Read in any hidden serialization magic
	s.defaultReadObject();

        // Read in size
        int size = s.readInt();

        // Initialize header
        header = new Entry(null, null, null);
        header.next = header.previous = header;

	// Read in all elements in the proper order.
	for (int i=0; i<size; i++)
            add(s.readObject());
    }
}