package java.util;
public abstract class AbstractList<E> extends AbstractCollection<E> implements List<E> {
/**
* Unique constructor. (For invocation by subclass constructors, typically
* implicit.)
*/
protected AbstractList() {
}
/**
* Append the specified element to the end of this list (optional operation).
*/
public boolean add(E e) {
add(size(), e);
return true;
}
/**
* Returns the element at the specified position in this list.
*/
abstract public E get(int index);
/**
* Replace the element at the specified position in this list with the specified element (optional operation).
*/
public E set(int index, E element) {
throw new UnsupportedOperationException();
}
/**
* Insert the specified element at the specified position in this list (optional operation).
*/
public void add(int index, E element) {
throw new UnsupportedOperationException();
}
/**
* Remove the element at the specified position in this list (optional operation).
*/
public E remove(int index) {
throw new UnsupportedOperationException();
}
// Search Operations
/**
* Returns the index of the first occurrence of the specified element in this list, or -1 if this list contains no element.
*/
public int indexOf(Object o) {
ListIterator <E> it = listIterator ();
if (o==null) {
while (it.hasNext())
if (it.next()==null)
return it.previousIndex();
} else {
while (it.hasNext())
if (o.equals(it.next()))
return it.previousIndex();
}
return -1;
}
/**
* Returns the index of the last occurrence of the specified element in this list, or -1 if this list contains no elements.
*/
public int lastIndexOf(Object o) {
ListIterator<E> it = listIterator(size());
if (o==null) {
while (it.hasPrevious())
if (it.previous()==null)
return it.nextIndex();
} else {
while (it.hasPrevious())
if (o.equals(it.previous()))
return it.nextIndex();
}
return -1;
}
// Bulk Operations
public void clear() {
removeRange(0, size());
}
public boolean addAll(int index, Collection<? extends E> c) {
rangeCheckForAdd (index);
boolean modified = false;
for (E e : c) {
add(index++, e);
modified = true;
}
return modified;
}
// Iterators
/**
* Returns an iterator of the elements in this list in the correct order.
*/
public Iterator<E> iterator() {
return new Itr();
}
/**
* Return list iterators (in correct order).
*/
public ListIterator <E> listIterator () {
return listIterator (0);
}
/**
* Returns a list iterator over the elements in this list (in correct order) starting at the specified position in the list.
*/
public ListIterator<E> listIterator(final int index) {
rangeCheckForAdd (index);
return new ListItr(index);
}
/**
* Returns an iterator of the elements in this list in the correct order.
*/
private class Itr implements Iterator<E> {
/**
* The index of the element to return to the next by subsequent calls.
*/
int cursor = 0;
/**
* The element index returned by the most recent or previous call. Resets to -1 if the call to delete removes this element.
*/
int lastRet = -1;
/**
* The modCount value that the iterator thinks the backing list should have. If this expectation is violated, the iterator detects concurrent modifications.
*/
int expectedModCount = modCount;
public boolean hasNext() {
return cursor != size();
}
public E next() {
checkForComodification();
try {
int i = cursor;
E next = get(i);
lastRet = i;
cursor = i + 1;
return next;
} catch (IndexOutOfBoundsException e) {
checkForComodification();
throw new NoSuchElementException();
}
}
public void remove() {
if (lastRet < 0)
throw new IllegalStateException();
checkForComodification();
try {
AbstractList.this.remove(lastRet);
if (lastRet < cursor)
cursor--;
lastRet = -1;
expectedModCount = modCount;
} catch (IndexOutOfBoundsException e) {
throw new ConcurrentModificationException();
}
}
final void checkForComodification() {
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
}
}
private class ListItr extends Itr implements ListIterator<E> {
ListItr(int index) {
cursor = index;
}
public boolean hasPrevious() {
return cursor != 0;
}
public E previous() {
checkForComodification();
try {
int i = cursor - 1;
E previous = get(i);
lastRet = cursor = i;
return previous;
} catch (IndexOutOfBoundsException e) {
checkForComodification();
throw new NoSuchElementException();
}
}
public int nextIndex() {
return cursor;
}
public int previousIndex() {
return cursor-1;
}
public void set(E e) {
if (lastRet < 0)
throw new IllegalStateException();
checkForComodification();
try {
AbstractList.this.set(lastRet, e);
expectedModCount = modCount;
} catch (IndexOutOfBoundsException ex) {
throw new ConcurrentModificationException();
}
}
public void add(E e) {
checkForComodification();
try {
int i = cursor;
AbstractList.this.add(i, e);
lastRet = -1;
cursor = i + 1;
expectedModCount = modCount;
} catch (IndexOutOfBoundsException ex) {
throw new ConcurrentModificationException();
}
}
}
/**
* Return the list between subscripts [fromIndex, toIndex]
*/
public List<E> subList(int fromIndex, int toIndex) {
return (this instanceof RandomAccess ?
new RandomAccessSubList<>(this, fromIndex, toIndex) :
new SubList<>(this, fromIndex, toIndex));
}
// Comparison and hashing
public boolean equals(Object o) {
if (o == this)
return true;
if (!(o instanceof List))
return false;
ListIterator <E> e1 = listIterator ();
ListIterator<?> e2 = ((List<?>) o).listIterator();
while (e1.hasNext() && e2.hasNext()) {
And o1 = e1.next();
Object o2 = e2.next();
if (!(o1==null ? o2==null : o1.equals(o2)))
return false;
}
return !(e1.hasNext() || e2.hasNext());
}
public int hashCode() {
int hashCode = 1;
for (E e : this)
hashCode = 31*hashCode + (e==null ? 0 : e.hashCode());
return hashCode;
}
/**
* removes from this list all elements with indices between fromIndex, contains and toIndex,
*/
protected void removeRange(int fromIndex, int toIndex) {
ListIterator<E> it = listIterator(fromIndex);
for (int i=0, n=toIndex-fromIndex; i<n; i++) {
it.next();
it.remove();
}
}
/**
* The number of structural modifications to this list.
*/
protected transient int modCount = 0;
private void rangeCheckForAdd(int index) {
if (index < 0 || index > size())
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
private String outOfBoundsMsg(int index) {
return "Index: "+index+", Size: "+size();
}
}
/**
*AbstractList does not support the methods in SubList by default.
*/
class SubList<E> extends AbstractList<E> {
private final AbstractList<E> l;
private final int offset;
private int size;
SubList(AbstractList<E> list, int fromIndex, int toIndex) {
if (fromIndex < 0)
throw new IndexOutOfBoundsException("fromIndex = " + fromIndex);
if (toIndex > list.size())
throw new IndexOutOfBoundsException("toIndex = " + toIndex);
if (fromIndex > toIndex)
throw new IllegalArgumentException("fromIndex(" + fromIndex +
") > toIndex(" + toIndex + ")");
l = list;
offset = fromIndex;
size = toIndex - fromIndex;
this.modCount = l.modCount;
}
public E set(int index, E element) {
rangeCheck (index);
checkForComodification();
return l.set(index+offset, element);
}
public E get(int index) {
rangeCheck (index);
checkForComodification();
return l.get(index+offset);
}
public int size() {
checkForComodification();
return size;
}
public void add(int index, E element) {
rangeCheckForAdd (index);
checkForComodification();
l.add(index+offset, element);
this.modCount = l.modCount;
size++;
}
public E remove(int index) {
rangeCheck (index);
checkForComodification();
E result = l.remove(index+offset);
this.modCount = l.modCount;
size--;
return result;
}
protected void removeRange(int fromIndex, int toIndex) {
checkForComodification();
l.removeRange(fromIndex+offset, toIndex+offset);
this.modCount = l.modCount;
size -= (toIndex-fromIndex);
}
public boolean addAll(Collection<? extends E> c) {
return addAll(size, c);
}
public boolean addAll(int index, Collection<? extends E> c) {
rangeCheckForAdd (index);
int cSize = c.size();
if (cSize==0)
return false;
checkForComodification();
l.addAll(offset+index, c);
this.modCount = l.modCount;
size += cSize;
return true;
}
public Iterator<E> iterator() {
return listIterator ();
}
public ListIterator<E> listIterator(final int index) {
checkForComodification();
rangeCheckForAdd (index);
return new ListIterator<E>() {
private final ListIterator<E> i = l.listIterator(index+offset);
public boolean hasNext() {
return nextIndex() < size;
}
public E next() {
if (hasNext())
return i.next();
else
throw new NoSuchElementException();
}
public boolean hasPrevious() {
return previousIndex() >= 0;
}
public E previous() {
if (hasPrevious())
return i.previous();
else
throw new NoSuchElementException();
}
public int nextIndex() {
return i.nextIndex() - offset;
}
public int previousIndex() {
return i.previousIndex() - offset;
}
public void remove() {
i.remove();
SubList.this.modCount = l.modCount;
size--;
}
public void set(E e) {
i.set(e);
}
public void add(E e) {
i.add(e);
SubList.this.modCount = l.modCount;
size++;
}
};
}
public List<E> subList(int fromIndex, int toIndex) {
return new SubList<>(this, fromIndex, toIndex);
}
private void rangeCheck(int index) {
if (index < 0 || index >= size)
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
private void rangeCheckForAdd(int index) {
if (index < 0 || index > size)
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
private String outOfBoundsMsg(int index) {
return "Index: "+index+", Size: "+size;
}
private void checkForComodification() {
if (this.modCount != l.modCount)
throw new ConcurrentModificationException();
}
}
//Quick access mechanism
class RandomAccessSubList<E> extends SubList<E> implements RandomAccess {
RandomAccessSubList(AbstractList<E> list, int fromIndex, int toIndex) {
super(list, fromIndex, toIndex);
}
public List<E> subList(int fromIndex, int toIndex) {
return new RandomAccessSubList<>(this, fromIndex, toIndex);
}
}