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| public class LinkedList extends AbstractSequentialList
implements List, Cloneable, java.io.Serializable
{
private transient Entry header = new Entry(null, null, null);
private transient int size = 0;
public LinkedList() {
header.next = header.previous = header;
}
public LinkedList(Collection c) {
this();
addAll(c);
}
public Object getFirst() {
if (size==0)
throw new NoSuchElementException();
return header.next.element;
}
public Object getLast() {
if (size==0)
throw new NoSuchElementException();
return header.previous.element;
}
public Object removeFirst() {
Object first = header.next.element;
remove(header.next);
return first;
}
public Object removeLast() {
Object last = header.previous.element;
remove(header.previous);
return last;
}
public void addFirst(Object o) {
addBefore(o, header.next);
}
public void addLast(Object o) {
addBefore(o, header);
}
public boolean contains(Object o) {
return indexOf(o) != -1;
}
public int size() {
return size;
}
public boolean add(Object o) {
addBefore(o, header);
return true;
}
public boolean remove(Object o) {
if (o==null) {
for (Entry e = header.next; e != header; e = e.next) {
if (e.element==null) {
remove(e);
return true;
}
}
} else {
for (Entry e = header.next; e != header; e = e.next) {
if (o.equals(e.element)) {
remove(e);
return true;
}
}
}
return false;
}
public boolean addAll(Collection c) {
return addAll(size, c);
}
public boolean addAll(int index, Collection c) {
Object[] a = c.toArray();
int numNew = a.length;
if (numNew==0)
return false;
modCount++;
Entry successor = (index==size ? header : entry(index));
Entry predecessor = successor.previous;
for (int i=0; i<numNew; i++) {
Entry e = new Entry(a[i], successor, predecessor);
predecessor.next = e;
predecessor = e;
}
successor.previous = predecessor;
size += numNew;
return true;
}
public void clear() {
modCount++;
header.next = header.previous = header;
size = 0;
}
public Object get(int index) {
return entry(index).element;
}
public Object set(int index, Object element) {
Entry e = entry(index);
Object oldVal = e.element;
e.element = element;
return oldVal;
}
public void add(int index, Object element) {
addBefore(element, (index==size ? header : entry(index)));
}
public Object remove(int index) {
Entry e = entry(index);
remove(e);
return e.element;
}
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
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;
}
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;
}
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();
Entry saveNext = lastReturned.next; //ibm@63937.1
try {
LinkedList.this.remove(lastReturned);
} catch (NoSuchElementException e) {
throw new IllegalStateException();
}
if (next==lastReturned)
next = saveNext; //ibm@63937.1
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;
e.next = null; /*ibm@59875.1*/
e.previous = null; /*ibm@59875.1*/
size--;
modCount++;
}
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;
}
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;
}
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;
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);
}
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());
}
} |
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