+ * This class is a member of the
+ *
* Java Collections Framework.
*
+ * @param the type of elements in this list
+ *
* @author Josh Bloch
* @author Neal Gafter
- * @version %I%, %G%
- * @see Collection
- * @see List
- * @see LinkedList
- * @see Vector
+ * @see Collection
+ * @see List
+ * @see LinkedList
+ * @see Vector
* @since 1.2
*/
-
public class ArrayList extends AbstractList
implements List, RandomAccess, Cloneable, java.io.Serializable
{
private static final long serialVersionUID = 8683452581122892189L;
/**
+ * Default initial capacity.
+ */
+ private static final int DEFAULT_CAPACITY = 10;
+
+ /**
+ * Shared empty array instance used for empty instances.
+ */
+ private static final Object[] EMPTY_ELEMENTDATA = {};
+
+ /**
+ * Shared empty array instance used for default sized empty instances. We
+ * distinguish this from EMPTY_ELEMENTDATA to know how much to inflate when
+ * first element is added.
+ */
+ private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA = {};
+
+ /**
* The array buffer into which the elements of the ArrayList are stored.
- * The capacity of the ArrayList is the length of this array buffer.
+ * The capacity of the ArrayList is the length of this array buffer. Any
+ * empty ArrayList with elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA
+ * will be expanded to DEFAULT_CAPACITY when the first element is added.
*/
- private transient Object[] elementData;
+ transient Object[] elementData; // non-private to simplify nested class access
/**
* The size of the ArrayList (the number of elements it contains).
@@ -101,102 +145,134 @@ public class ArrayList extends Abstra
/**
* Constructs an empty list with the specified initial capacity.
*
- * @param initialCapacity the initial capacity of the list
+ * @param initialCapacity the initial capacity of the list
* @throws IllegalArgumentException if the specified initial capacity
* is negative
*/
public ArrayList(int initialCapacity) {
- super();
- if (initialCapacity < 0)
+ if (initialCapacity > 0) {
+ this.elementData = new Object[initialCapacity];
+ } else if (initialCapacity == 0) {
+ this.elementData = EMPTY_ELEMENTDATA;
+ } else {
throw new IllegalArgumentException("Illegal Capacity: "+
initialCapacity);
- this.elementData = new Object[initialCapacity];
+ }
}
/**
* Constructs an empty list with an initial capacity of ten.
*/
public ArrayList() {
- this(10);
+ this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
}
/**
* Constructs a list containing the elements of the specified
* collection, in the order they are returned by the collection's
- * iterator. The ArrayList instance has an initial capacity of
- * 110% the size of the specified collection.
+ * iterator.
*
* @param c the collection whose elements are to be placed into this list
* @throws NullPointerException if the specified collection is null
*/
public ArrayList(Collection c) {
- int size = c.size();
- // 10% for growth
- int cap = ((size/10)+1)*11;
- if (cap > 0) {
- Object[] a = new Object[cap];
- a[size] = a[size+1] = UNALLOCATED;
- Object[] b = c.toArray(a);
- if (b[size] == null && b[size+1] == UNALLOCATED) {
- b[size+1] = null;
- elementData = b;
- this.size = size;
- return;
- }
- }
- initFromConcurrentlyMutating(c);
- }
-
- private void initFromConcurrentlyMutating(Collection c) {
- elementData = c.toArray();
- size = elementData.length;
- // c.toArray might (incorrectly) not return Object[] (see 6260652)
- if (elementData.getClass() != Object[].class)
- elementData = Arrays.copyOf(elementData, size, Object[].class);
+ elementData = c.toArray();
+ if ((size = elementData.length) != 0) {
+ // defend against c.toArray (incorrectly) not returning Object[]
+ // (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652)
+ if (elementData.getClass() != Object[].class)
+ elementData = Arrays.copyOf(elementData, size, Object[].class);
+ } else {
+ // replace with empty array.
+ this.elementData = EMPTY_ELEMENTDATA;
+ }
}
- private final static Object UNALLOCATED = new Object();
-
/**
- * Trims the capacity of this ArrayList instance to be the
+ * Trims the capacity of this {@code ArrayList} instance to be the
* list's current size. An application can use this operation to minimize
- * the storage of an ArrayList instance.
+ * the storage of an {@code ArrayList} instance.
*/
public void trimToSize() {
- modCount++;
- int oldCapacity = elementData.length;
- if (size < oldCapacity) {
- elementData = Arrays.copyOf(elementData, size);
- }
+ modCount++;
+ if (size < elementData.length) {
+ elementData = (size == 0)
+ ? EMPTY_ELEMENTDATA
+ : Arrays.copyOf(elementData, size);
+ }
}
/**
- * Increases the capacity of this ArrayList instance, if
+ * Increases the capacity of this {@code ArrayList} instance, if
* necessary, to ensure that it can hold at least the number of elements
* specified by the minimum capacity argument.
*
* @param minCapacity the desired minimum capacity
*/
public void ensureCapacity(int minCapacity) {
- modCount++;
- if (minCapacity > elementData.length)
- growArray(minCapacity);
+ if (minCapacity > elementData.length
+ && !(elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA
+ && minCapacity <= DEFAULT_CAPACITY)) {
+ modCount++;
+ grow(minCapacity);
+ }
}
/**
- * Increases the capacity of the array.
+ * The maximum size of array to allocate (unless necessary).
+ * Some VMs reserve some header words in an array.
+ * Attempts to allocate larger arrays may result in
+ * OutOfMemoryError: Requested array size exceeds VM limit
+ */
+ private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
+
+ /**
+ * Increases the capacity to ensure that it can hold at least the
+ * number of elements specified by the minimum capacity argument.
*
* @param minCapacity the desired minimum capacity
+ * @throws OutOfMemoryError if minCapacity is less than zero
*/
- private void growArray(int minCapacity) {
- int oldCapacity = elementData.length;
- // Double size if small; else grow by 50%
- int newCapacity = ((oldCapacity < 64)?
- (oldCapacity * 2):
- ((oldCapacity * 3)/2 + 1));
- if (newCapacity < minCapacity)
- newCapacity = minCapacity;
- elementData = Arrays.copyOf(elementData, newCapacity);
+ private Object[] grow(int minCapacity) {
+ return elementData = Arrays.copyOf(elementData,
+ newCapacity(minCapacity));
+ }
+
+ private Object[] grow() {
+ return grow(size + 1);
+ }
+
+ /**
+ * Returns a capacity at least as large as the given minimum capacity.
+ * Returns the current capacity increased by 50% if that suffices.
+ * Will not return a capacity greater than MAX_ARRAY_SIZE unless
+ * the given minimum capacity is greater than MAX_ARRAY_SIZE.
+ *
+ * @param minCapacity the desired minimum capacity
+ * @throws OutOfMemoryError if minCapacity is less than zero
+ */
+ private int newCapacity(int minCapacity) {
+ // overflow-conscious code
+ int oldCapacity = elementData.length;
+ int newCapacity = oldCapacity + (oldCapacity >> 1);
+ if (newCapacity - minCapacity <= 0) {
+ if (elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA)
+ return Math.max(DEFAULT_CAPACITY, minCapacity);
+ if (minCapacity < 0) // overflow
+ throw new OutOfMemoryError();
+ return minCapacity;
+ }
+ return (newCapacity - MAX_ARRAY_SIZE <= 0)
+ ? newCapacity
+ : hugeCapacity(minCapacity);
+ }
+
+ private static int hugeCapacity(int minCapacity) {
+ if (minCapacity < 0) // overflow
+ throw new OutOfMemoryError();
+ return (minCapacity > MAX_ARRAY_SIZE)
+ ? Integer.MAX_VALUE
+ : MAX_ARRAY_SIZE;
}
/**
@@ -205,87 +281,105 @@ public class ArrayList extends Abstra
* @return the number of elements in this list
*/
public int size() {
- return size;
+ return size;
}
/**
- * Returns true if this list contains no elements.
+ * Returns {@code true} if this list contains no elements.
*
- * @return true if this list contains no elements
+ * @return {@code true} if this list contains no elements
*/
public boolean isEmpty() {
- return size == 0;
+ return size == 0;
}
/**
- * Returns true if this list contains the specified element.
- * More formally, returns true if and only if this list contains
- * at least one element e such that
- * (o==null ? e==null : o.equals(e)).
+ * Returns {@code true} if this list contains the specified element.
+ * More formally, returns {@code true} if and only if this list contains
+ * at least one element {@code e} such that
+ * {@code Objects.equals(o, e)}.
*
* @param o element whose presence in this list is to be tested
- * @return true if this list contains the specified element
+ * @return {@code true} if this list contains the specified element
*/
public boolean contains(Object o) {
- return indexOf(o) >= 0;
+ return indexOf(o) >= 0;
}
/**
* Returns the index of the first occurrence of the specified element
* in this list, or -1 if this list does not contain the element.
- * More formally, returns the lowest index i such that
- * (o==null ? get(i)==null : o.equals(get(i))),
+ * More formally, returns the lowest index {@code i} such that
+ * {@code Objects.equals(o, get(i))},
* or -1 if there is no such index.
*/
public int indexOf(Object o) {
- if (o == null) {
- for (int i = 0; i < size; i++)
- if (elementData[i]==null)
- return i;
- } else {
- for (int i = 0; i < size; i++)
- if (o.equals(elementData[i]))
- return i;
- }
- return -1;
+ return indexOfRange(o, 0, size);
+ }
+
+ int indexOfRange(Object o, int start, int end) {
+ Object[] es = elementData;
+ if (o == null) {
+ for (int i = start; i < end; i++) {
+ if (es[i] == null) {
+ return i;
+ }
+ }
+ } else {
+ for (int i = start; i < end; i++) {
+ if (o.equals(es[i])) {
+ return i;
+ }
+ }
+ }
+ return -1;
}
/**
* Returns the index of the last occurrence of the specified element
* in this list, or -1 if this list does not contain the element.
- * More formally, returns the highest index i such that
- * (o==null ? get(i)==null : o.equals(get(i))),
+ * More formally, returns the highest index {@code i} such that
+ * {@code Objects.equals(o, get(i))},
* or -1 if there is no such index.
*/
public int lastIndexOf(Object o) {
- if (o == null) {
- for (int i = size-1; i >= 0; i--)
- if (elementData[i]==null)
- return i;
- } else {
- for (int i = size-1; i >= 0; i--)
- if (o.equals(elementData[i]))
- return i;
- }
- return -1;
+ return lastIndexOfRange(o, 0, size);
+ }
+
+ int lastIndexOfRange(Object o, int start, int end) {
+ Object[] es = elementData;
+ if (o == null) {
+ for (int i = end - 1; i >= start; i--) {
+ if (es[i] == null) {
+ return i;
+ }
+ }
+ } else {
+ for (int i = end - 1; i >= start; i--) {
+ if (o.equals(es[i])) {
+ return i;
+ }
+ }
+ }
+ return -1;
}
/**
- * Returns a shallow copy of this ArrayList instance. (The
+ * Returns a shallow copy of this {@code ArrayList} instance. (The
* elements themselves are not copied.)
*
- * @return a clone of this ArrayList instance
+ * @return a clone of this {@code ArrayList} instance
*/
public Object clone() {
- try {
- ArrayList v = (ArrayList) super.clone();
- v.elementData = Arrays.copyOf(elementData, size);
- v.modCount = 0;
- return v;
- } catch (CloneNotSupportedException e) {
- // this shouldn't happen, since we are Cloneable
- throw new InternalError();
- }
+ try {
+ ArrayList v = (ArrayList) super.clone();
+ v.elementData = Arrays.copyOf(elementData, size);
+ v.modCount = 0;
+ return v;
+ } catch (CloneNotSupportedException e) {
+ // this shouldn't happen, since we are Cloneable
+ throw new InternalError(e);
+ }
}
/**
@@ -317,7 +411,7 @@ public class ArrayList extends Abstra
* 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
+ * {@code null}. (This is useful in determining the length of the
* list only if the caller knows that the list does not contain
* any null elements.)
*
@@ -330,11 +424,12 @@ public class ArrayList extends Abstra
* this list
* @throws NullPointerException if the specified array is null
*/
+ @SuppressWarnings("unchecked")
public T[] toArray(T[] a) {
if (a.length < size)
// Make a new array of a's runtime type, but my contents:
return (T[]) Arrays.copyOf(elementData, size, a.getClass());
- System.arraycopy(elementData, 0, a, 0, size);
+ System.arraycopy(elementData, 0, a, 0, size);
if (a.length > size)
a[size] = null;
return a;
@@ -342,11 +437,14 @@ public class ArrayList extends Abstra
// Positional Access Operations
- /**
- * Create and return an appropriate exception for indexing errors
- */
- private static IndexOutOfBoundsException rangeException(int i, int s) {
- return new IndexOutOfBoundsException("Index: " + i + ", Size: " + s);
+ @SuppressWarnings("unchecked")
+ E elementData(int index) {
+ return (E) elementData[index];
+ }
+
+ @SuppressWarnings("unchecked")
+ static E elementAt(Object[] es, int index) {
+ return (E) es[index];
}
/**
@@ -357,9 +455,8 @@ public class ArrayList extends Abstra
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E get(int index) {
- if (index >= size)
- throw rangeException(index, size);
- return (E)elementData[index];
+ Objects.checkIndex(index, size);
+ return elementData(index);
}
/**
@@ -372,27 +469,34 @@ public class ArrayList extends Abstra
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E set(int index, E element) {
- if (index >= size)
- throw rangeException(index, size);
+ Objects.checkIndex(index, size);
+ E oldValue = elementData(index);
+ elementData[index] = element;
+ return oldValue;
+ }
- E oldValue = (E) elementData[index];
- elementData[index] = element;
- return oldValue;
+ /**
+ * This helper method split out from add(E) to keep method
+ * bytecode size under 35 (the -XX:MaxInlineSize default value),
+ * which helps when add(E) is called in a C1-compiled loop.
+ */
+ private void add(E e, Object[] elementData, int s) {
+ if (s == elementData.length)
+ elementData = grow();
+ elementData[s] = e;
+ size = s + 1;
}
/**
* Appends the specified element to the end of this list.
*
* @param e element to be appended to this list
- * @return true (as specified by {@link Collection#add})
+ * @return {@code true} (as specified by {@link Collection#add})
*/
public boolean add(E e) {
- ++modCount;
- int s = size++;
- if (s >= elementData.length)
- growArray(s + 1);
- elementData[s] = e;
- return true;
+ modCount++;
+ add(e, elementData, size);
+ return true;
}
/**
@@ -405,16 +509,18 @@ public class ArrayList extends Abstra
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public void add(int index, E element) {
- int s = size;
- if (index > s || index < 0)
- throw rangeException(index, s);
- ++modCount;
+ rangeCheckForAdd(index);
+ modCount++;
+ final int s;
+ Object[] elementData;
+ if ((s = size) == (elementData = this.elementData).length)
+ elementData = grow();
+ System.arraycopy(elementData, index,
+ elementData, index + 1,
+ s - index);
+ elementData[index] = element;
size = s + 1;
- if (s >= elementData.length)
- growArray(s + 1);
- System.arraycopy(elementData, index, elementData, index + 1,
- s - index);
- elementData[index] = element;
+ // checkInvariants();
}
/**
@@ -427,61 +533,146 @@ public class ArrayList extends Abstra
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E remove(int index) {
- int s = size - 1;
- if (index > s)
- throw rangeException(index, size);
- size = s;
- modCount++;
- Object oldValue = elementData[index];
- int numMoved = s - index;
- if (numMoved > 0)
- System.arraycopy(elementData, index+1, elementData, index,
- numMoved);
- elementData[s] = null; // forget removed element
- return (E)oldValue;
+ Objects.checkIndex(index, size);
+ final Object[] es = elementData;
+
+ @SuppressWarnings("unchecked") E oldValue = (E) es[index];
+ fastRemove(es, index);
+
+ // checkInvariants();
+ return oldValue;
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public boolean equals(Object o) {
+ if (o == this) {
+ return true;
+ }
+
+ if (!(o instanceof List)) {
+ return false;
+ }
+
+ final int expectedModCount = modCount;
+ // ArrayList can be subclassed and given arbitrary behavior, but we can
+ // still deal with the common case where o is ArrayList precisely
+ boolean equal = (o.getClass() == ArrayList.class)
+ ? equalsArrayList((ArrayList) o)
+ : equalsRange((List) o, 0, size);
+
+ checkForComodification(expectedModCount);
+ return equal;
+ }
+
+ boolean equalsRange(List other, int from, int to) {
+ final Object[] es = elementData;
+ if (to > es.length) {
+ throw new ConcurrentModificationException();
+ }
+ Iterator oit = other.iterator();
+ for (; from < to; from++) {
+ if (!oit.hasNext() || !Objects.equals(es[from], oit.next())) {
+ return false;
+ }
+ }
+ return !oit.hasNext();
+ }
+
+ private boolean equalsArrayList(ArrayList other) {
+ final int otherModCount = other.modCount;
+ final int s = size;
+ boolean equal;
+ if (equal = (s == other.size)) {
+ final Object[] otherEs = other.elementData;
+ final Object[] es = elementData;
+ if (s > es.length || s > otherEs.length) {
+ throw new ConcurrentModificationException();
+ }
+ for (int i = 0; i < s; i++) {
+ if (!Objects.equals(es[i], otherEs[i])) {
+ equal = false;
+ break;
+ }
+ }
+ }
+ other.checkForComodification(otherModCount);
+ return equal;
+ }
+
+ private void checkForComodification(final int expectedModCount) {
+ if (modCount != expectedModCount) {
+ throw new ConcurrentModificationException();
+ }
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public int hashCode() {
+ int expectedModCount = modCount;
+ int hash = hashCodeRange(0, size);
+ checkForComodification(expectedModCount);
+ return hash;
+ }
+
+ int hashCodeRange(int from, int to) {
+ final Object[] es = elementData;
+ if (to > es.length) {
+ throw new ConcurrentModificationException();
+ }
+ int hashCode = 1;
+ for (int i = from; i < to; i++) {
+ Object e = es[i];
+ hashCode = 31 * hashCode + (e == null ? 0 : e.hashCode());
+ }
+ return hashCode;
}
/**
* Removes the first occurrence of the specified element from this list,
* if it is present. If the list does not contain the element, it is
* unchanged. More formally, removes the element with the lowest index
- * i such that
- * (o==null ? get(i)==null : o.equals(get(i)))
- * (if such an element exists). Returns true if this list
+ * {@code i} such that
+ * {@code Objects.equals(o, get(i))}
+ * (if such an element exists). Returns {@code true} if this list
* contained the specified element (or equivalently, if this list
* changed as a result of the call).
*
* @param o element to be removed from this list, if present
- * @return true if this list contained the specified element
+ * @return {@code true} if this list contained the specified element
*/
public boolean remove(Object o) {
- if (o == null) {
- for (int index = 0; index < size; index++)
- if (elementData[index] == null) {
- fastRemove(index);
- return true;
- }
- } else {
- for (int index = 0; index < size; index++)
- if (o.equals(elementData[index])) {
- fastRemove(index);
- return true;
- }
+ final Object[] es = elementData;
+ final int size = this.size;
+ int i = 0;
+ found: {
+ if (o == null) {
+ for (; i < size; i++)
+ if (es[i] == null)
+ break found;
+ } else {
+ for (; i < size; i++)
+ if (o.equals(es[i]))
+ break found;
+ }
+ return false;
}
- return false;
+ fastRemove(es, i);
+ return true;
}
- /*
+ /**
* Private remove method that skips bounds checking and does not
* return the value removed.
*/
- private void fastRemove(int index) {
+ private void fastRemove(Object[] es, int i) {
modCount++;
- int numMoved = size - index - 1;
- if (numMoved > 0)
- System.arraycopy(elementData, index+1, elementData, index,
- numMoved);
- elementData[--size] = null; // Let gc do its work
+ final int newSize;
+ if ((newSize = size - 1) > i)
+ System.arraycopy(es, i + 1, es, i, newSize - i);
+ es[size = newSize] = null;
}
/**
@@ -489,13 +680,10 @@ public class ArrayList extends Abstra
* be empty after this call returns.
*/
public void clear() {
- modCount++;
-
- // Let gc do its work
- for (int i = 0; i < size; i++)
- elementData[i] = null;
-
- size = 0;
+ modCount++;
+ final Object[] es = elementData;
+ for (int to = size, i = size = 0; i < to; i++)
+ es[i] = null;
}
/**
@@ -508,16 +696,23 @@ public class ArrayList extends Abstra
* list is nonempty.)
*
* @param c collection containing elements to be added to this list
- * @return true if this list changed as a result of the call
+ * @return {@code true} if this list changed as a result of the call
* @throws NullPointerException if the specified collection is null
*/
public boolean addAll(Collection c) {
- Object[] a = c.toArray();
+ Object[] a = c.toArray();
+ modCount++;
int numNew = a.length;
- ensureCapacity(size + numNew); // Increments modCount
- System.arraycopy(a, 0, elementData, size, numNew);
- size += numNew;
- return numNew != 0;
+ if (numNew == 0)
+ return false;
+ Object[] elementData;
+ final int s;
+ if (numNew > (elementData = this.elementData).length - (s = size))
+ elementData = grow(s + numNew);
+ System.arraycopy(a, 0, elementData, s, numNew);
+ size = s + numNew;
+ // checkInvariants();
+ return true;
}
/**
@@ -531,231 +726,1043 @@ public class ArrayList extends Abstra
* @param index index at which to insert the first element from the
* specified collection
* @param c collection containing elements to be added to this list
- * @return true if this list changed as a result of the call
+ * @return {@code true} if this list changed as a result of the call
* @throws IndexOutOfBoundsException {@inheritDoc}
* @throws NullPointerException if the specified collection is null
*/
public boolean addAll(int index, Collection c) {
- if (index > size || index < 0)
- throw new IndexOutOfBoundsException(
- "Index: " + index + ", Size: " + size);
-
- Object[] a = c.toArray();
- int numNew = a.length;
- ensureCapacity(size + numNew); // Increments modCount
-
- int numMoved = size - index;
- if (numMoved > 0)
- System.arraycopy(elementData, index, elementData, index + numNew,
- numMoved);
+ rangeCheckForAdd(index);
+
+ Object[] a = c.toArray();
+ modCount++;
+ int numNew = a.length;
+ if (numNew == 0)
+ return false;
+ Object[] elementData;
+ final int s;
+ if (numNew > (elementData = this.elementData).length - (s = size))
+ elementData = grow(s + numNew);
+ int numMoved = s - index;
+ if (numMoved > 0)
+ System.arraycopy(elementData, index,
+ elementData, index + numNew,
+ numMoved);
System.arraycopy(a, 0, elementData, index, numNew);
- size += numNew;
- return numNew != 0;
+ size = s + numNew;
+ // checkInvariants();
+ return true;
}
/**
* Removes from this list all of the elements whose index is between
- * fromIndex, inclusive, and toIndex, exclusive.
+ * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
* Shifts any succeeding elements to the left (reduces their index).
- * This call shortens the list by (toIndex - fromIndex) elements.
- * (If toIndex==fromIndex, this operation has no effect.)
+ * This call shortens the list by {@code (toIndex - fromIndex)} elements.
+ * (If {@code toIndex==fromIndex}, this operation has no effect.)
*
- * @param fromIndex index of first element to be removed
- * @param toIndex index after last element to be removed
- * @throws IndexOutOfBoundsException if fromIndex or toIndex out of
- * range (fromIndex < 0 || fromIndex >= size() || toIndex
- * > size() || toIndex < fromIndex)
+ * @throws IndexOutOfBoundsException if {@code fromIndex} or
+ * {@code toIndex} is out of range
+ * ({@code fromIndex < 0 ||
+ * toIndex > size() ||
+ * toIndex < fromIndex})
*/
protected void removeRange(int fromIndex, int toIndex) {
- modCount++;
- int numMoved = size - toIndex;
- System.arraycopy(elementData, toIndex, elementData, fromIndex,
- numMoved);
+ if (fromIndex > toIndex) {
+ throw new IndexOutOfBoundsException(
+ outOfBoundsMsg(fromIndex, toIndex));
+ }
+ modCount++;
+ shiftTailOverGap(elementData, fromIndex, toIndex);
+ // checkInvariants();
+ }
- // Let gc do its work
- int newSize = size - (toIndex-fromIndex);
- while (size != newSize)
- elementData[--size] = null;
+ /** Erases the gap from lo to hi, by sliding down following elements. */
+ private void shiftTailOverGap(Object[] es, int lo, int hi) {
+ System.arraycopy(es, hi, es, lo, size - hi);
+ for (int to = size, i = (size -= hi - lo); i < to; i++)
+ es[i] = null;
}
/**
- * Save the state of the ArrayList instance to a stream (that
- * is, serialize it).
+ * A version of rangeCheck used by add and addAll.
+ */
+ private void rangeCheckForAdd(int index) {
+ if (index > size || index < 0)
+ throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
+ }
+
+ /**
+ * Constructs an IndexOutOfBoundsException detail message.
+ * Of the many possible refactorings of the error handling code,
+ * this "outlining" performs best with both server and client VMs.
+ */
+ private String outOfBoundsMsg(int index) {
+ return "Index: "+index+", Size: "+size;
+ }
+
+ /**
+ * A version used in checking (fromIndex > toIndex) condition
+ */
+ private static String outOfBoundsMsg(int fromIndex, int toIndex) {
+ return "From Index: " + fromIndex + " > To Index: " + toIndex;
+ }
+
+ /**
+ * Removes from this list all of its elements that are contained in the
+ * specified collection.
+ *
+ * @param c collection containing elements to be removed from this list
+ * @return {@code true} if this list changed as a result of the call
+ * @throws ClassCastException if the class of an element of this list
+ * is incompatible with the specified collection
+ * (optional)
+ * @throws NullPointerException if this list contains a null element and the
+ * specified collection does not permit null elements
+ * (optional),
+ * or if the specified collection is null
+ * @see Collection#contains(Object)
+ */
+ public boolean removeAll(Collection c) {
+ return batchRemove(c, false, 0, size);
+ }
+
+ /**
+ * Retains only the elements in this list that are contained in the
+ * specified collection. In other words, removes from this list all
+ * of its elements that are not contained in the specified collection.
*
- * @serialData The length of the array backing the ArrayList
+ * @param c collection containing elements to be retained in this list
+ * @return {@code true} if this list changed as a result of the call
+ * @throws ClassCastException if the class of an element of this list
+ * is incompatible with the specified collection
+ * (optional)
+ * @throws NullPointerException if this list contains a null element and the
+ * specified collection does not permit null elements
+ * (optional),
+ * or if the specified collection is null
+ * @see Collection#contains(Object)
+ */
+ public boolean retainAll(Collection c) {
+ return batchRemove(c, true, 0, size);
+ }
+
+ boolean batchRemove(Collection c, boolean complement,
+ final int from, final int end) {
+ Objects.requireNonNull(c);
+ final Object[] es = elementData;
+ int r;
+ // Optimize for initial run of survivors
+ for (r = from;; r++) {
+ if (r == end)
+ return false;
+ if (c.contains(es[r]) != complement)
+ break;
+ }
+ int w = r++;
+ try {
+ for (Object e; r < end; r++)
+ if (c.contains(e = es[r]) == complement)
+ es[w++] = e;
+ } catch (Throwable ex) {
+ // Preserve behavioral compatibility with AbstractCollection,
+ // even if c.contains() throws.
+ System.arraycopy(es, r, es, w, end - r);
+ w += end - r;
+ throw ex;
+ } finally {
+ modCount += end - w;
+ shiftTailOverGap(es, w, end);
+ }
+ // checkInvariants();
+ return true;
+ }
+
+ /**
+ * Saves the state of the {@code ArrayList} instance to a stream
+ * (that is, serializes it).
+ *
+ * @param s the stream
+ * @throws java.io.IOException if an I/O error occurs
+ * @serialData The length of the array backing the {@code ArrayList}
* instance is emitted (int), followed by all of its elements
- * (each an Object) in the proper order.
+ * (each an {@code Object}) in the proper order.
*/
private void writeObject(java.io.ObjectOutputStream s)
- throws java.io.IOException{
- // Write out element count, and any hidden stuff
- int expectedModCount = modCount;
- s.defaultWriteObject();
+ throws java.io.IOException {
+ // Write out element count, and any hidden stuff
+ int expectedModCount = modCount;
+ s.defaultWriteObject();
- // Write out array length
- s.writeInt(elementData.length);
+ // Write out size as capacity for behavioral compatibility with clone()
+ s.writeInt(size);
- // Write out all elements in the proper order.
- for (int i=0; iArrayList instance from a stream (that is,
- * deserialize it).
+ * Reconstitutes the {@code ArrayList} instance from a stream (that is,
+ * deserializes it).
+ * @param s the stream
+ * @throws ClassNotFoundException if the class of a serialized object
+ * could not be found
+ * @throws java.io.IOException if an I/O error occurs
*/
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
- // Read in size, and any hidden stuff
- s.defaultReadObject();
- // Read in array length and allocate array
- int arrayLength = s.readInt();
- Object[] a = elementData = new Object[arrayLength];
+ // Read in size, and any hidden stuff
+ s.defaultReadObject();
- // Read in all elements in the proper order.
- for (int i=0; i 0) {
+ // like clone(), allocate array based upon size not capacity
+ jsr166.Platform.checkArray(s, Object[].class, size);
+ Object[] elements = new Object[size];
+
+ // Read in all elements in the proper order.
+ for (int i = 0; i < size; i++) {
+ elements[i] = s.readObject();
+ }
+ elementData = elements;
+ } else if (size == 0) {
+ elementData = EMPTY_ELEMENTDATA;
+ } else {
+ throw new java.io.InvalidObjectException("Invalid size: " + size);
+ }
+ }
/**
- * Returns a list-iterator of the elements in this list (in proper
+ * Returns a list iterator over the elements in this list (in proper
* sequence), starting at the specified position in the list.
- * Obeys the general contract of List.listIterator(int).
+ * The specified index indicates the first element that would be
+ * returned by an initial call to {@link ListIterator#next next}.
+ * An initial call to {@link ListIterator#previous previous} would
+ * return the element with the specified index minus one.
+ *
+ *
The returned list iterator is fail-fast.
*
- * The list-iterator is fail-fast: if the list is structurally
- * modified at any time after the Iterator is created, in any way except
- * through the list-iterator's own remove or add
- * methods, the list-iterator will throw a
- * ConcurrentModificationException. 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 the first element to be returned from the
- * list-iterator (by a call to next)
- * @return a ListIterator of the elements in this list (in proper
- * sequence), starting at the specified position in the list
* @throws IndexOutOfBoundsException {@inheritDoc}
- * @see List#listIterator(int)
*/
public ListIterator listIterator(int index) {
- if (index < 0 || index > size)
- throw new IndexOutOfBoundsException("Index: "+index);
- return new ArrayListIterator(index);
+ rangeCheckForAdd(index);
+ return new ListItr(index);
+ }
+
+ /**
+ * Returns a list iterator over the elements in this list (in proper
+ * sequence).
+ *
+ * The returned list iterator is fail-fast.
+ *
+ * @see #listIterator(int)
+ */
+ public ListIterator listIterator() {
+ return new ListItr(0);
}
/**
* Returns an iterator over the elements in this list in proper sequence.
*
+ * The returned iterator is fail-fast.
+ *
* @return an iterator over the elements in this list in proper sequence
*/
public Iterator iterator() {
- return new ArrayListIterator(0);
+ return new Itr();
}
/**
- * A streamlined version of AbstractList.Itr
+ * An optimized version of AbstractList.Itr
*/
- final class ArrayListIterator implements ListIterator {
- int cursor; // index of next element to return;
- int lastRet; // index of last element, or -1 if no such
- int expectedModCount; // to check for CME
+ private class Itr implements Iterator {
+ int cursor; // index of next element to return
+ int lastRet = -1; // index of last element returned; -1 if no such
+ int expectedModCount = modCount;
+
+ // prevent creating a synthetic constructor
+ Itr() {}
+
+ public boolean hasNext() {
+ return cursor != size;
+ }
- ArrayListIterator(int index) {
- cursor = index;
- lastRet = -1;
- expectedModCount = modCount;
- }
+ @SuppressWarnings("unchecked")
+ public E next() {
+ checkForComodification();
+ int i = cursor;
+ if (i >= size)
+ throw new NoSuchElementException();
+ Object[] elementData = ArrayList.this.elementData;
+ if (i >= elementData.length)
+ throw new ConcurrentModificationException();
+ cursor = i + 1;
+ return (E) elementData[lastRet = i];
+ }
+
+ public void remove() {
+ if (lastRet < 0)
+ throw new IllegalStateException();
+ checkForComodification();
+
+ try {
+ ArrayList.this.remove(lastRet);
+ cursor = lastRet;
+ lastRet = -1;
+ expectedModCount = modCount;
+ } catch (IndexOutOfBoundsException ex) {
+ throw new ConcurrentModificationException();
+ }
+ }
+
+ @Override
+ public void forEachRemaining(Consumer action) {
+ Objects.requireNonNull(action);
+ final int size = ArrayList.this.size;
+ int i = cursor;
+ if (i < size) {
+ final Object[] es = elementData;
+ if (i >= es.length)
+ throw new ConcurrentModificationException();
+ for (; i < size && modCount == expectedModCount; i++)
+ action.accept(elementAt(es, i));
+ // update once at end to reduce heap write traffic
+ cursor = i;
+ lastRet = i - 1;
+ checkForComodification();
+ }
+ }
+
+ final void checkForComodification() {
+ if (modCount != expectedModCount)
+ throw new ConcurrentModificationException();
+ }
+ }
- public boolean hasNext() {
- return cursor < size;
- }
+ /**
+ * An optimized version of AbstractList.ListItr
+ */
+ private class ListItr extends Itr implements ListIterator {
+ ListItr(int index) {
+ super();
+ cursor = index;
+ }
- public boolean hasPrevious() {
- return cursor > 0;
- }
+ public boolean hasPrevious() {
+ return cursor != 0;
+ }
- public int nextIndex() {
- return cursor;
- }
+ public int nextIndex() {
+ return cursor;
+ }
- public int previousIndex() {
- return cursor - 1;
- }
+ public int previousIndex() {
+ return cursor - 1;
+ }
- public E next() {
- if (expectedModCount == modCount) {
+ @SuppressWarnings("unchecked")
+ public E previous() {
+ checkForComodification();
+ int i = cursor - 1;
+ if (i < 0)
+ throw new NoSuchElementException();
+ Object[] elementData = ArrayList.this.elementData;
+ if (i >= elementData.length)
+ throw new ConcurrentModificationException();
+ cursor = i;
+ return (E) elementData[lastRet = i];
+ }
+
+ public void set(E e) {
+ if (lastRet < 0)
+ throw new IllegalStateException();
+ checkForComodification();
+
+ try {
+ ArrayList.this.set(lastRet, e);
+ } catch (IndexOutOfBoundsException ex) {
+ throw new ConcurrentModificationException();
+ }
+ }
+
+ public void add(E e) {
+ checkForComodification();
+
+ try {
int i = cursor;
- if (i < size) {
+ ArrayList.this.add(i, e);
+ cursor = i + 1;
+ lastRet = -1;
+ expectedModCount = modCount;
+ } catch (IndexOutOfBoundsException ex) {
+ throw new ConcurrentModificationException();
+ }
+ }
+ }
+
+ /**
+ * Returns a view of the portion of this list between the specified
+ * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. (If
+ * {@code fromIndex} and {@code toIndex} are equal, the returned list is
+ * empty.) The returned list is backed by this list, so non-structural
+ * changes in the returned list are reflected in this list, and vice-versa.
+ * The returned list supports all of the optional list operations.
+ *
+ * This method eliminates the need for explicit range operations (of
+ * the sort that commonly exist for arrays). Any operation that expects
+ * a list can be used as a range operation by passing a subList view
+ * instead of a whole list. For example, the following idiom
+ * removes a range of elements from a list:
+ *
+ * list.subList(from, to).clear();
+ *
+ * Similar idioms may be constructed for {@link #indexOf(Object)} and
+ * {@link #lastIndexOf(Object)}, and all of the algorithms in the
+ * {@link Collections} class can be applied to a subList.
+ *
+ * The semantics of the list returned by this method become undefined if
+ * the backing list (i.e., this list) is structurally modified in
+ * any way other than via the returned list. (Structural modifications are
+ * those that change the size of this list, or otherwise perturb it in such
+ * a fashion that iterations in progress may yield incorrect results.)
+ *
+ * @throws IndexOutOfBoundsException {@inheritDoc}
+ * @throws IllegalArgumentException {@inheritDoc}
+ */
+ public List subList(int fromIndex, int toIndex) {
+ subListRangeCheck(fromIndex, toIndex, size);
+ return new SubList<>(this, fromIndex, toIndex);
+ }
+
+ private static class SubList extends AbstractList implements RandomAccess {
+ private final ArrayList root;
+ private final SubList parent;
+ private final int offset;
+ private int size;
+
+ /**
+ * Constructs a sublist of an arbitrary ArrayList.
+ */
+ public SubList(ArrayList root, int fromIndex, int toIndex) {
+ this.root = root;
+ this.parent = null;
+ this.offset = fromIndex;
+ this.size = toIndex - fromIndex;
+ this.modCount = root.modCount;
+ }
+
+ /**
+ * Constructs a sublist of another SubList.
+ */
+ private SubList(SubList parent, int fromIndex, int toIndex) {
+ this.root = parent.root;
+ this.parent = parent;
+ this.offset = parent.offset + fromIndex;
+ this.size = toIndex - fromIndex;
+ this.modCount = root.modCount;
+ }
+
+ public E set(int index, E element) {
+ Objects.checkIndex(index, size);
+ checkForComodification();
+ E oldValue = root.elementData(offset + index);
+ root.elementData[offset + index] = element;
+ return oldValue;
+ }
+
+ public E get(int index) {
+ Objects.checkIndex(index, size);
+ checkForComodification();
+ return root.elementData(offset + index);
+ }
+
+ public int size() {
+ checkForComodification();
+ return size;
+ }
+
+ public void add(int index, E element) {
+ rangeCheckForAdd(index);
+ checkForComodification();
+ root.add(offset + index, element);
+ updateSizeAndModCount(1);
+ }
+
+ public E remove(int index) {
+ Objects.checkIndex(index, size);
+ checkForComodification();
+ E result = root.remove(offset + index);
+ updateSizeAndModCount(-1);
+ return result;
+ }
+
+ protected void removeRange(int fromIndex, int toIndex) {
+ checkForComodification();
+ root.removeRange(offset + fromIndex, offset + toIndex);
+ updateSizeAndModCount(fromIndex - toIndex);
+ }
+
+ public boolean addAll(Collection c) {
+ return addAll(this.size, c);
+ }
+
+ public boolean addAll(int index, Collection c) {
+ rangeCheckForAdd(index);
+ int cSize = c.size();
+ if (cSize==0)
+ return false;
+ checkForComodification();
+ root.addAll(offset + index, c);
+ updateSizeAndModCount(cSize);
+ return true;
+ }
+
+ public void replaceAll(UnaryOperator operator) {
+ root.replaceAllRange(operator, offset, offset + size);
+ }
+
+ public boolean removeAll(Collection c) {
+ return batchRemove(c, false);
+ }
+
+ public boolean retainAll(Collection c) {
+ return batchRemove(c, true);
+ }
+
+ private boolean batchRemove(Collection c, boolean complement) {
+ checkForComodification();
+ int oldSize = root.size;
+ boolean modified =
+ root.batchRemove(c, complement, offset, offset + size);
+ if (modified)
+ updateSizeAndModCount(root.size - oldSize);
+ return modified;
+ }
+
+ public boolean removeIf(Predicate filter) {
+ checkForComodification();
+ int oldSize = root.size;
+ boolean modified = root.removeIf(filter, offset, offset + size);
+ if (modified)
+ updateSizeAndModCount(root.size - oldSize);
+ return modified;
+ }
+
+ public Object[] toArray() {
+ checkForComodification();
+ return Arrays.copyOfRange(root.elementData, offset, offset + size);
+ }
+
+ @SuppressWarnings("unchecked")
+ public T[] toArray(T[] a) {
+ checkForComodification();
+ if (a.length < size)
+ return (T[]) Arrays.copyOfRange(
+ root.elementData, offset, offset + size, a.getClass());
+ System.arraycopy(root.elementData, offset, a, 0, size);
+ if (a.length > size)
+ a[size] = null;
+ return a;
+ }
+
+ public boolean equals(Object o) {
+ if (o == this) {
+ return true;
+ }
+
+ if (!(o instanceof List)) {
+ return false;
+ }
+
+ boolean equal = root.equalsRange((List)o, offset, offset + size);
+ checkForComodification();
+ return equal;
+ }
+
+ public int hashCode() {
+ int hash = root.hashCodeRange(offset, offset + size);
+ checkForComodification();
+ return hash;
+ }
+
+ public int indexOf(Object o) {
+ int index = root.indexOfRange(o, offset, offset + size);
+ checkForComodification();
+ return index >= 0 ? index - offset : -1;
+ }
+
+ public int lastIndexOf(Object o) {
+ int index = root.lastIndexOfRange(o, offset, offset + size);
+ checkForComodification();
+ return index >= 0 ? index - offset : -1;
+ }
+
+ public boolean contains(Object o) {
+ return indexOf(o) >= 0;
+ }
+
+ public Iterator iterator() {
+ return listIterator();
+ }
+
+ public ListIterator listIterator(int index) {
+ checkForComodification();
+ rangeCheckForAdd(index);
+
+ return new ListIterator() {
+ int cursor = index;
+ int lastRet = -1;
+ int expectedModCount = root.modCount;
+
+ public boolean hasNext() {
+ return cursor != SubList.this.size;
+ }
+
+ @SuppressWarnings("unchecked")
+ public E next() {
+ checkForComodification();
+ int i = cursor;
+ if (i >= SubList.this.size)
+ throw new NoSuchElementException();
+ Object[] elementData = root.elementData;
+ if (offset + i >= elementData.length)
+ throw new ConcurrentModificationException();
+ cursor = i + 1;
+ return (E) elementData[offset + (lastRet = i)];
+ }
+
+ public boolean hasPrevious() {
+ return cursor != 0;
+ }
+
+ @SuppressWarnings("unchecked")
+ public E previous() {
+ checkForComodification();
+ int i = cursor - 1;
+ if (i < 0)
+ throw new NoSuchElementException();
+ Object[] elementData = root.elementData;
+ if (offset + i >= elementData.length)
+ throw new ConcurrentModificationException();
+ cursor = i;
+ return (E) elementData[offset + (lastRet = i)];
+ }
+
+ public void forEachRemaining(Consumer action) {
+ Objects.requireNonNull(action);
+ final int size = SubList.this.size;
+ int i = cursor;
+ if (i < size) {
+ final Object[] es = root.elementData;
+ if (offset + i >= es.length)
+ throw new ConcurrentModificationException();
+ for (; i < size && modCount == expectedModCount; i++)
+ action.accept(elementAt(es, offset + i));
+ // update once at end to reduce heap write traffic
+ cursor = i;
+ lastRet = i - 1;
+ checkForComodification();
+ }
+ }
+
+ public int nextIndex() {
+ return cursor;
+ }
+
+ public int previousIndex() {
+ return cursor - 1;
+ }
+
+ public void remove() {
+ if (lastRet < 0)
+ throw new IllegalStateException();
+ checkForComodification();
+
+ try {
+ SubList.this.remove(lastRet);
+ cursor = lastRet;
+ lastRet = -1;
+ expectedModCount = root.modCount;
+ } catch (IndexOutOfBoundsException ex) {
+ throw new ConcurrentModificationException();
+ }
+ }
+
+ public void set(E e) {
+ if (lastRet < 0)
+ throw new IllegalStateException();
+ checkForComodification();
+
+ try {
+ root.set(offset + lastRet, e);
+ } catch (IndexOutOfBoundsException ex) {
+ throw new ConcurrentModificationException();
+ }
+ }
+
+ public void add(E e) {
+ checkForComodification();
+
try {
- E e = (E)elementData[i];
- lastRet = i;
+ int i = cursor;
+ SubList.this.add(i, e);
cursor = i + 1;
- return e;
- } catch (IndexOutOfBoundsException fallthrough) {
+ lastRet = -1;
+ expectedModCount = root.modCount;
+ } catch (IndexOutOfBoundsException ex) {
+ throw new ConcurrentModificationException();
}
}
- }
- // Prefer reporting CME if applicable on failures
- if (expectedModCount == modCount)
- throw new NoSuchElementException();
+
+ final void checkForComodification() {
+ if (root.modCount != expectedModCount)
+ throw new ConcurrentModificationException();
+ }
+ };
+ }
+
+ public List subList(int fromIndex, int toIndex) {
+ subListRangeCheck(fromIndex, toIndex, size);
+ return new SubList<>(this, fromIndex, toIndex);
+ }
+
+ private void rangeCheckForAdd(int index) {
+ if (index < 0 || index > this.size)
+ throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
+ }
+
+ private String outOfBoundsMsg(int index) {
+ return "Index: "+index+", Size: "+this.size;
+ }
+
+ private void checkForComodification() {
+ if (root.modCount != modCount)
+ throw new ConcurrentModificationException();
+ }
+
+ private void updateSizeAndModCount(int sizeChange) {
+ SubList slist = this;
+ do {
+ slist.size += sizeChange;
+ slist.modCount = root.modCount;
+ slist = slist.parent;
+ } while (slist != null);
+ }
+
+ public Spliterator spliterator() {
+ checkForComodification();
+
+ // ArrayListSpliterator not used here due to late-binding
+ return new Spliterator() {
+ private int index = offset; // current index, modified on advance/split
+ private int fence = -1; // -1 until used; then one past last index
+ private int expectedModCount; // initialized when fence set
+
+ private int getFence() { // initialize fence to size on first use
+ int hi; // (a specialized variant appears in method forEach)
+ if ((hi = fence) < 0) {
+ expectedModCount = modCount;
+ hi = fence = offset + size;
+ }
+ return hi;
+ }
+
+ public ArrayList.ArrayListSpliterator trySplit() {
+ int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
+ // ArrayListSpliterator can be used here as the source is already bound
+ return (lo >= mid) ? null : // divide range in half unless too small
+ root.new ArrayListSpliterator(lo, index = mid, expectedModCount);
+ }
+
+ public boolean tryAdvance(Consumer action) {
+ Objects.requireNonNull(action);
+ int hi = getFence(), i = index;
+ if (i < hi) {
+ index = i + 1;
+ @SuppressWarnings("unchecked") E e = (E)root.elementData[i];
+ action.accept(e);
+ if (root.modCount != expectedModCount)
+ throw new ConcurrentModificationException();
+ return true;
+ }
+ return false;
+ }
+
+ public void forEachRemaining(Consumer action) {
+ Objects.requireNonNull(action);
+ int i, hi, mc; // hoist accesses and checks from loop
+ ArrayList lst = root;
+ Object[] a;
+ if ((a = lst.elementData) != null) {
+ if ((hi = fence) < 0) {
+ mc = modCount;
+ hi = offset + size;
+ }
+ else
+ mc = expectedModCount;
+ if ((i = index) >= 0 && (index = hi) <= a.length) {
+ for (; i < hi; ++i) {
+ @SuppressWarnings("unchecked") E e = (E) a[i];
+ action.accept(e);
+ }
+ if (lst.modCount == mc)
+ return;
+ }
+ }
+ throw new ConcurrentModificationException();
+ }
+
+ public long estimateSize() {
+ return getFence() - index;
+ }
+
+ public int characteristics() {
+ return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
+ }
+ };
+ }
+ }
+
+ /**
+ * @throws NullPointerException {@inheritDoc}
+ */
+ @Override
+ public void forEach(Consumer action) {
+ Objects.requireNonNull(action);
+ final int expectedModCount = modCount;
+ final Object[] es = elementData;
+ final int size = this.size;
+ for (int i = 0; modCount == expectedModCount && i < size; i++)
+ action.accept(elementAt(es, i));
+ if (modCount != expectedModCount)
throw new ConcurrentModificationException();
- }
+ }
- public E previous() {
- if (expectedModCount == modCount) {
- int i = cursor - 1;
- if (i < size) {
- try {
- E e = (E)elementData[i];
- lastRet = i;
- cursor = i;
- return e;
- } catch (IndexOutOfBoundsException fallthrough) {
+ /**
+ * Creates a late-binding
+ * and fail-fast {@link Spliterator} over the elements in this
+ * list.
+ *
+ * The {@code Spliterator} reports {@link Spliterator#SIZED},
+ * {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}.
+ * Overriding implementations should document the reporting of additional
+ * characteristic values.
+ *
+ * @return a {@code Spliterator} over the elements in this list
+ * @since 1.8
+ */
+ @Override
+ public Spliterator spliterator() {
+ return new ArrayListSpliterator(0, -1, 0);
+ }
+
+ /** Index-based split-by-two, lazily initialized Spliterator */
+ final class ArrayListSpliterator implements Spliterator {
+
+ /*
+ * If ArrayLists were immutable, or structurally immutable (no
+ * adds, removes, etc), we could implement their spliterators
+ * with Arrays.spliterator. Instead we detect as much
+ * interference during traversal as practical without
+ * sacrificing much performance. We rely primarily on
+ * modCounts. These are not guaranteed to detect concurrency
+ * violations, and are sometimes overly conservative about
+ * within-thread interference, but detect enough problems to
+ * be worthwhile in practice. To carry this out, we (1) lazily
+ * initialize fence and expectedModCount until the latest
+ * point that we need to commit to the state we are checking
+ * against; thus improving precision. (This doesn't apply to
+ * SubLists, that create spliterators with current non-lazy
+ * values). (2) We perform only a single
+ * ConcurrentModificationException check at the end of forEach
+ * (the most performance-sensitive method). When using forEach
+ * (as opposed to iterators), we can normally only detect
+ * interference after actions, not before. Further
+ * CME-triggering checks apply to all other possible
+ * violations of assumptions for example null or too-small
+ * elementData array given its size(), that could only have
+ * occurred due to interference. This allows the inner loop
+ * of forEach to run without any further checks, and
+ * simplifies lambda-resolution. While this does entail a
+ * number of checks, note that in the common case of
+ * list.stream().forEach(a), no checks or other computation
+ * occur anywhere other than inside forEach itself. The other
+ * less-often-used methods cannot take advantage of most of
+ * these streamlinings.
+ */
+
+ private int index; // current index, modified on advance/split
+ private int fence; // -1 until used; then one past last index
+ private int expectedModCount; // initialized when fence set
+
+ /** Creates new spliterator covering the given range. */
+ ArrayListSpliterator(int origin, int fence, int expectedModCount) {
+ this.index = origin;
+ this.fence = fence;
+ this.expectedModCount = expectedModCount;
+ }
+
+ private int getFence() { // initialize fence to size on first use
+ int hi; // (a specialized variant appears in method forEach)
+ if ((hi = fence) < 0) {
+ expectedModCount = modCount;
+ hi = fence = size;
+ }
+ return hi;
+ }
+
+ public ArrayListSpliterator trySplit() {
+ int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
+ return (lo >= mid) ? null : // divide range in half unless too small
+ new ArrayListSpliterator(lo, index = mid, expectedModCount);
+ }
+
+ public boolean tryAdvance(Consumer action) {
+ if (action == null)
+ throw new NullPointerException();
+ int hi = getFence(), i = index;
+ if (i < hi) {
+ index = i + 1;
+ @SuppressWarnings("unchecked") E e = (E)elementData[i];
+ action.accept(e);
+ if (modCount != expectedModCount)
+ throw new ConcurrentModificationException();
+ return true;
+ }
+ return false;
+ }
+
+ public void forEachRemaining(Consumer action) {
+ int i, hi, mc; // hoist accesses and checks from loop
+ Object[] a;
+ if (action == null)
+ throw new NullPointerException();
+ if ((a = elementData) != null) {
+ if ((hi = fence) < 0) {
+ mc = modCount;
+ hi = size;
+ }
+ else
+ mc = expectedModCount;
+ if ((i = index) >= 0 && (index = hi) <= a.length) {
+ for (; i < hi; ++i) {
+ @SuppressWarnings("unchecked") E e = (E) a[i];
+ action.accept(e);
}
+ if (modCount == mc)
+ return;
}
}
- if (expectedModCount == modCount)
- throw new NoSuchElementException();
throw new ConcurrentModificationException();
}
- public void remove() {
- if (lastRet < 0)
- throw new IllegalStateException();
+ public long estimateSize() {
+ return getFence() - index;
+ }
+
+ public int characteristics() {
+ return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
+ }
+ }
+
+ // A tiny bit set implementation
+
+ private static long[] nBits(int n) {
+ return new long[((n - 1) >> 6) + 1];
+ }
+ private static void setBit(long[] bits, int i) {
+ bits[i >> 6] |= 1L << i;
+ }
+ private static boolean isClear(long[] bits, int i) {
+ return (bits[i >> 6] & (1L << i)) == 0;
+ }
+
+ /**
+ * @throws NullPointerException {@inheritDoc}
+ */
+ @Override
+ public boolean removeIf(Predicate filter) {
+ return removeIf(filter, 0, size);
+ }
+
+ /**
+ * Removes all elements satisfying the given predicate, from index
+ * i (inclusive) to index end (exclusive).
+ */
+ boolean removeIf(Predicate filter, int i, final int end) {
+ Objects.requireNonNull(filter);
+ int expectedModCount = modCount;
+ final Object[] es = elementData;
+ // Optimize for initial run of survivors
+ for (; i < end && !filter.test(elementAt(es, i)); i++)
+ ;
+ // Tolerate predicates that reentrantly access the collection for
+ // read (but writers still get CME), so traverse once to find
+ // elements to delete, a second pass to physically expunge.
+ if (i < end) {
+ final int beg = i;
+ final long[] deathRow = nBits(end - beg);
+ deathRow[0] = 1L; // set bit 0
+ for (i = beg + 1; i < end; i++)
+ if (filter.test(elementAt(es, i)))
+ setBit(deathRow, i - beg);
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
- ArrayList.this.remove(lastRet);
- if (lastRet < cursor)
- cursor--;
- lastRet = -1;
- expectedModCount = modCount;
- }
-
- public void set(E e) {
- if (lastRet < 0)
- throw new IllegalStateException();
+ modCount++;
+ int w = beg;
+ for (i = beg; i < end; i++)
+ if (isClear(deathRow, i - beg))
+ es[w++] = es[i];
+ shiftTailOverGap(es, w, end);
+ // checkInvariants();
+ return true;
+ } else {
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
- ArrayList.this.set(lastRet, e);
- expectedModCount = modCount;
- }
+ // checkInvariants();
+ return false;
+ }
+ }
- public void add(E e) {
- if (modCount != expectedModCount)
- throw new ConcurrentModificationException();
- ArrayList.this.add(cursor++, e);
- lastRet = -1;
- expectedModCount = modCount;
- }
+ @Override
+ public void replaceAll(UnaryOperator operator) {
+ replaceAllRange(operator, 0, size);
+ }
+
+ private void replaceAllRange(UnaryOperator operator, int i, int end) {
+ Objects.requireNonNull(operator);
+ final int expectedModCount = modCount;
+ final Object[] es = elementData;
+ for (; modCount == expectedModCount && i < end; i++)
+ es[i] = operator.apply(elementAt(es, i));
+ if (modCount != expectedModCount)
+ throw new ConcurrentModificationException();
+ // checkInvariants();
}
+ @Override
+ @SuppressWarnings("unchecked")
+ public void sort(Comparator c) {
+ final int expectedModCount = modCount;
+ Arrays.sort((E[]) elementData, 0, size, c);
+ if (modCount != expectedModCount)
+ throw new ConcurrentModificationException();
+ modCount++;
+ // checkInvariants();
+ }
+
+ void checkInvariants() {
+ // assert size >= 0;
+ // assert size == elementData.length || elementData[size] == null;
+ }
}