--- jsr166/src/main/java/util/ArrayList.java 2011/05/07 12:22:02 1.32
+++ jsr166/src/main/java/util/ArrayList.java 2016/10/17 21:46:27 1.33
@@ -1,12 +1,12 @@
/*
- * Copyright (c) 1997, 2008, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation. Sun designates this
+ * published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
- * by Sun in the LICENSE file that accompanied this code.
+ * by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
@@ -25,34 +25,38 @@
package java.util;
+import java.util.function.Consumer;
+import java.util.function.Predicate;
+import java.util.function.UnaryOperator;
+
/**
- * Resizable-array implementation of the List interface. Implements
+ * Resizable-array implementation of the {@code List} interface. Implements
* all optional list operations, and permits all elements, including
- * null. In addition to implementing the List interface,
+ * {@code null}. In addition to implementing the {@code List} interface,
* this class provides methods to manipulate the size of the array that is
* used internally to store the list. (This class is roughly equivalent to
- * Vector, except that it is unsynchronized.)
+ * {@code Vector}, except that it is unsynchronized.)
*
- * The size, isEmpty, get, set,
- * iterator, and listIterator operations run in constant
- * time. The add operation runs in amortized constant time,
+ *
The {@code size}, {@code isEmpty}, {@code get}, {@code set},
+ * {@code iterator}, and {@code listIterator} operations run in constant
+ * time. The {@code add} operation runs in amortized constant time,
* that is, adding n elements requires O(n) time. All of the other operations
* run in linear time (roughly speaking). The constant factor is low compared
- * to that for the LinkedList implementation.
+ * to that for the {@code LinkedList} implementation.
*
- *
Each ArrayList instance has a capacity. The capacity is
+ *
Each {@code ArrayList} instance has a capacity. The capacity is
* the size of the array used to store the elements in the list. It is always
* at least as large as the list size. As elements are added to an ArrayList,
* its capacity grows automatically. The details of the growth policy are not
* specified beyond the fact that adding an element has constant amortized
* time cost.
*
- *
An application can increase the capacity of an ArrayList instance
- * before adding a large number of elements using the ensureCapacity
+ *
An application can increase the capacity of an {@code ArrayList} instance
+ * before adding a large number of elements using the {@code ensureCapacity}
* operation. This may reduce the amount of incremental reallocation.
*
*
Note that this implementation is not synchronized.
- * If multiple threads access an ArrayList instance concurrently,
+ * If multiple threads access an {@code ArrayList} instance concurrently,
* and at least one of the threads modifies the list structurally, it
* must be synchronized externally. (A structural modification is
* any operation that adds or deletes one or more elements, or explicitly
@@ -66,7 +70,7 @@ package java.util;
* unsynchronized access to the list:
* List list = Collections.synchronizedList(new ArrayList(...));
*
- *
+ *
* The iterators returned by this class's {@link #iterator() iterator} and
* {@link #listIterator(int) listIterator} methods are fail-fast:
* if the list is structurally modified at any time after the iterator is
@@ -90,6 +94,8 @@ package java.util;
*
* Java Collections Framework.
*
+ * @param the type of elements in this list
+ *
* @author Josh Bloch
* @author Neal Gafter
* @see Collection
@@ -105,10 +111,29 @@ public class ArrayList extends Abstra
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).
@@ -125,18 +150,21 @@ public class ArrayList extends Abstra
* 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;
}
/**
@@ -149,45 +177,105 @@ public class ArrayList extends Abstra
*/
public ArrayList(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);
+ 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;
+ }
}
/**
- * 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);
+ 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
+ * @param minCapacity the desired minimum capacity
*/
public void ensureCapacity(int minCapacity) {
- modCount++;
- int oldCapacity = elementData.length;
- if (minCapacity > oldCapacity) {
- int newCapacity = (oldCapacity * 3)/2 + 1;
- if (newCapacity < minCapacity)
- newCapacity = minCapacity;
- // minCapacity is usually close to size, so this is a win:
- elementData = Arrays.copyOf(elementData, newCapacity);
+ if (minCapacity > elementData.length
+ && !(elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA
+ && minCapacity <= DEFAULT_CAPACITY)) {
+ modCount++;
+ grow(minCapacity);
}
}
/**
+ * 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 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;
+ }
+
+ /**
* Returns the number of elements in this list.
*
* @return the number of elements in this list
@@ -197,22 +285,22 @@ public class ArrayList extends Abstra
}
/**
- * 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;
}
/**
- * 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;
@@ -221,8 +309,8 @@ public class ArrayList extends Abstra
/**
* 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) {
@@ -241,8 +329,8 @@ public class ArrayList extends Abstra
/**
* 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) {
@@ -259,21 +347,20 @@ public class ArrayList extends Abstra
}
/**
- * 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 {
- @SuppressWarnings("unchecked")
- ArrayList v = (ArrayList) super.clone();
+ 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();
+ throw new InternalError(e);
}
}
@@ -306,7 +393,7 @@ 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.)
*
@@ -345,8 +432,7 @@ public class ArrayList extends Abstra
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E get(int index) {
- rangeCheck(index);
-
+ Objects.checkIndex(index, size);
return elementData(index);
}
@@ -360,22 +446,33 @@ public class ArrayList extends Abstra
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E set(int index, E element) {
- rangeCheck(index);
-
+ Objects.checkIndex(index, size);
E oldValue = 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) {
- ensureCapacity(size + 1); // Increments modCount!!
- elementData[size++] = e;
+ modCount++;
+ add(e, elementData, size);
return true;
}
@@ -390,12 +487,16 @@ public class ArrayList extends Abstra
*/
public void add(int index, E element) {
rangeCheckForAdd(index);
-
- ensureCapacity(size+1); // Increments modCount!!
- System.arraycopy(elementData, index, elementData, index + 1,
- size - 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++;
+ size = s + 1;
}
/**
@@ -408,7 +509,7 @@ public class ArrayList extends Abstra
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public E remove(int index) {
- rangeCheck(index);
+ Objects.checkIndex(index, size);
modCount++;
E oldValue = elementData(index);
@@ -417,7 +518,7 @@ public class ArrayList extends Abstra
if (numMoved > 0)
System.arraycopy(elementData, index+1, elementData, index,
numMoved);
- elementData[--size] = null; // Let gc do its work
+ elementData[--size] = null; // clear to let GC do its work
return oldValue;
}
@@ -426,14 +527,14 @@ public class ArrayList extends Abstra
* 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) {
@@ -462,7 +563,7 @@ public class ArrayList extends Abstra
if (numMoved > 0)
System.arraycopy(elementData, index+1, elementData, index,
numMoved);
- elementData[--size] = null; // Let gc do its work
+ elementData[--size] = null; // clear to let GC do its work
}
/**
@@ -472,7 +573,7 @@ public class ArrayList extends Abstra
public void clear() {
modCount++;
- // Let gc do its work
+ // clear to let GC do its work
for (int i = 0; i < size; i++)
elementData[i] = null;
@@ -489,16 +590,22 @@ 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();
+ 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;
+ return true;
}
/**
@@ -512,7 +619,7 @@ 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
*/
@@ -520,17 +627,23 @@ public class ArrayList extends Abstra
rangeCheckForAdd(index);
Object[] a = c.toArray();
+ modCount++;
int numNew = a.length;
- ensureCapacity(size + numNew); // Increments modCount
+ if (numNew == 0)
+ return false;
+ Object[] elementData;
+ final int s;
+ if (numNew > (elementData = this.elementData).length - (s = size))
+ elementData = grow(s + numNew);
- int numMoved = size - index;
+ int numMoved = s - index;
if (numMoved > 0)
- System.arraycopy(elementData, index, elementData, index + numNew,
+ System.arraycopy(elementData, index,
+ elementData, index + numNew,
numMoved);
-
System.arraycopy(a, 0, elementData, index, numNew);
- size += numNew;
- return numNew != 0;
+ size = s + numNew;
+ return true;
}
/**
@@ -543,31 +656,25 @@ public class ArrayList extends Abstra
* @throws IndexOutOfBoundsException if {@code fromIndex} or
* {@code toIndex} is out of range
* ({@code fromIndex < 0 ||
- * fromIndex >= size() ||
* toIndex > size() ||
* toIndex < fromIndex})
*/
protected void removeRange(int fromIndex, int toIndex) {
+ if (fromIndex > toIndex) {
+ throw new IndexOutOfBoundsException(
+ outOfBoundsMsg(fromIndex, toIndex));
+ }
modCount++;
int numMoved = size - toIndex;
System.arraycopy(elementData, toIndex, elementData, fromIndex,
numMoved);
- // Let gc do its work
+ // clear to let GC do its work
int newSize = size - (toIndex-fromIndex);
- while (size != newSize)
- elementData[--size] = null;
- }
-
- /**
- * Checks if the given index is in range. If not, throws an appropriate
- * runtime exception. This method does *not* check if the index is
- * negative: It is always used immediately prior to an array access,
- * which throws an ArrayIndexOutOfBoundsException if index is negative.
- */
- private void rangeCheck(int index) {
- if (index >= size)
- throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
+ for (int i = newSize; i < size; i++) {
+ elementData[i] = null;
+ }
+ size = newSize;
}
/**
@@ -588,19 +695,29 @@ public class ArrayList extends Abstra
}
/**
+ * 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)
+ * 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),
+ * specified collection does not permit null elements
+ * (optional),
* or if the specified collection is null
* @see Collection#contains(Object)
*/
public boolean removeAll(Collection c) {
+ Objects.requireNonNull(c);
return batchRemove(c, false);
}
@@ -612,13 +729,16 @@ public class ArrayList extends Abstra
* @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)
+ * 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),
+ * specified collection does not permit null elements
+ * (optional),
* or if the specified collection is null
* @see Collection#contains(Object)
*/
public boolean retainAll(Collection c) {
+ Objects.requireNonNull(c);
return batchRemove(c, true);
}
@@ -640,6 +760,7 @@ public class ArrayList extends Abstra
w += size - r;
}
if (w != size) {
+ // clear to let GC do its work
for (int i = w; i < size; i++)
elementData[i] = null;
modCount += size - w;
@@ -651,12 +772,12 @@ public class ArrayList extends Abstra
}
/**
- * Save the state of the ArrayList instance to a stream (that
+ * Save the state of the {@code ArrayList} instance to a stream (that
* is, serialize it).
*
- * @serialData The length of the array backing the ArrayList
+ * @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{
@@ -664,35 +785,47 @@ public class ArrayList extends Abstra
int expectedModCount = modCount;
s.defaultWriteObject();
- // Write out array length
- s.writeInt(elementData.length);
+ // Write out size as capacity for behavioural 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,
+ * Reconstitute the {@code ArrayList} instance from a stream (that is,
* deserialize it).
*/
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 all elements in the proper order.
- for (int i=0; i 0) {
+ // like clone(), allocate array based upon size not capacity
+ 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);
+ }
}
/**
@@ -708,8 +841,7 @@ public class ArrayList extends Abstra
* @throws IndexOutOfBoundsException {@inheritDoc}
*/
public ListIterator listIterator(int index) {
- if (index < 0 || index > size)
- throw new IndexOutOfBoundsException("Index: "+index);
+ rangeCheckForAdd(index);
return new ListItr(index);
}
@@ -744,6 +876,9 @@ public class ArrayList extends Abstra
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;
}
@@ -776,6 +911,28 @@ public class ArrayList extends Abstra
}
}
+ @Override
+ @SuppressWarnings("unchecked")
+ public void forEachRemaining(Consumer consumer) {
+ Objects.requireNonNull(consumer);
+ final int size = ArrayList.this.size;
+ int i = cursor;
+ if (i >= size) {
+ return;
+ }
+ final Object[] elementData = ArrayList.this.elementData;
+ if (i >= elementData.length) {
+ throw new ConcurrentModificationException();
+ }
+ while (i != size && modCount == expectedModCount) {
+ consumer.accept((E) elementData[i++]);
+ }
+ // update once at end of iteration to reduce heap write traffic
+ cursor = i;
+ lastRet = i - 1;
+ checkForComodification();
+ }
+
final void checkForComodification() {
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
@@ -874,76 +1031,75 @@ public class ArrayList extends Abstra
*/
public List subList(int fromIndex, int toIndex) {
subListRangeCheck(fromIndex, toIndex, size);
- return new SubList(this, 0, fromIndex, toIndex);
+ return new SubList<>(this, fromIndex, toIndex);
}
- static void subListRangeCheck(int fromIndex, int toIndex, int size) {
- if (fromIndex < 0)
- throw new IndexOutOfBoundsException("fromIndex = " + fromIndex);
- if (toIndex > size)
- throw new IndexOutOfBoundsException("toIndex = " + toIndex);
- if (fromIndex > toIndex)
- throw new IllegalArgumentException("fromIndex(" + fromIndex +
- ") > toIndex(" + toIndex + ")");
- }
-
- private class SubList extends AbstractList implements RandomAccess {
- private final AbstractList parent;
- private final int parentOffset;
+ private static class SubList extends AbstractList implements RandomAccess {
+ private final ArrayList root;
+ private final SubList parent;
private final int offset;
- int size;
+ private int size;
- SubList(AbstractList parent,
- int offset, int fromIndex, int toIndex) {
+ /**
+ * 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.parentOffset = fromIndex;
- this.offset = offset + fromIndex;
+ this.offset = parent.offset + fromIndex;
this.size = toIndex - fromIndex;
- this.modCount = ArrayList.this.modCount;
+ this.modCount = root.modCount;
}
- public E set(int index, E e) {
- rangeCheck(index);
+ public E set(int index, E element) {
+ Objects.checkIndex(index, size);
checkForComodification();
- E oldValue = ArrayList.this.elementData(offset + index);
- ArrayList.this.elementData[offset + index] = e;
+ E oldValue = root.elementData(offset + index);
+ root.elementData[offset + index] = element;
return oldValue;
}
public E get(int index) {
- rangeCheck(index);
+ Objects.checkIndex(index, size);
checkForComodification();
- return ArrayList.this.elementData(offset + index);
+ return root.elementData(offset + index);
}
public int size() {
checkForComodification();
- return this.size;
+ return size;
}
- public void add(int index, E e) {
+ public void add(int index, E element) {
rangeCheckForAdd(index);
checkForComodification();
- parent.add(parentOffset + index, e);
- this.modCount = parent.modCount;
- this.size++;
+ root.add(offset + index, element);
+ updateSizeAndModCount(1);
}
public E remove(int index) {
- rangeCheck(index);
+ Objects.checkIndex(index, size);
checkForComodification();
- E result = parent.remove(parentOffset + index);
- this.modCount = parent.modCount;
- this.size--;
+ E result = root.remove(offset + index);
+ updateSizeAndModCount(-1);
return result;
}
protected void removeRange(int fromIndex, int toIndex) {
checkForComodification();
- parent.removeRange(parentOffset + fromIndex,
- parentOffset + toIndex);
- this.modCount = parent.modCount;
- this.size -= toIndex - fromIndex;
+ root.removeRange(offset + fromIndex, offset + toIndex);
+ updateSizeAndModCount(fromIndex - toIndex);
}
public boolean addAll(Collection c) {
@@ -955,11 +1111,9 @@ public class ArrayList extends Abstra
int cSize = c.size();
if (cSize==0)
return false;
-
checkForComodification();
- parent.addAll(parentOffset + index, c);
- this.modCount = parent.modCount;
- this.size += cSize;
+ root.addAll(offset + index, c);
+ updateSizeAndModCount(cSize);
return true;
}
@@ -967,15 +1121,14 @@ public class ArrayList extends Abstra
return listIterator();
}
- public ListIterator listIterator(final int index) {
+ public ListIterator listIterator(int index) {
checkForComodification();
rangeCheckForAdd(index);
- final int offset = this.offset;
return new ListIterator() {
int cursor = index;
int lastRet = -1;
- int expectedModCount = ArrayList.this.modCount;
+ int expectedModCount = root.modCount;
public boolean hasNext() {
return cursor != SubList.this.size;
@@ -987,7 +1140,7 @@ public class ArrayList extends Abstra
int i = cursor;
if (i >= SubList.this.size)
throw new NoSuchElementException();
- Object[] elementData = ArrayList.this.elementData;
+ Object[] elementData = root.elementData;
if (offset + i >= elementData.length)
throw new ConcurrentModificationException();
cursor = i + 1;
@@ -1004,13 +1157,33 @@ public class ArrayList extends Abstra
int i = cursor - 1;
if (i < 0)
throw new NoSuchElementException();
- Object[] elementData = ArrayList.this.elementData;
+ Object[] elementData = root.elementData;
if (offset + i >= elementData.length)
throw new ConcurrentModificationException();
cursor = i;
return (E) elementData[offset + (lastRet = i)];
}
+ @SuppressWarnings("unchecked")
+ public void forEachRemaining(Consumer consumer) {
+ Objects.requireNonNull(consumer);
+ final int size = SubList.this.size;
+ int i = cursor;
+ if (i >= size) {
+ return;
+ }
+ final Object[] elementData = root.elementData;
+ if (offset + i >= elementData.length) {
+ throw new ConcurrentModificationException();
+ }
+ while (i != size && modCount == expectedModCount) {
+ consumer.accept((E) elementData[offset + (i++)]);
+ }
+ // update once at end of iteration to reduce heap write traffic
+ lastRet = cursor = i;
+ checkForComodification();
+ }
+
public int nextIndex() {
return cursor;
}
@@ -1028,7 +1201,7 @@ public class ArrayList extends Abstra
SubList.this.remove(lastRet);
cursor = lastRet;
lastRet = -1;
- expectedModCount = ArrayList.this.modCount;
+ expectedModCount = root.modCount;
} catch (IndexOutOfBoundsException ex) {
throw new ConcurrentModificationException();
}
@@ -1040,7 +1213,7 @@ public class ArrayList extends Abstra
checkForComodification();
try {
- ArrayList.this.set(offset + lastRet, e);
+ root.set(offset + lastRet, e);
} catch (IndexOutOfBoundsException ex) {
throw new ConcurrentModificationException();
}
@@ -1054,14 +1227,14 @@ public class ArrayList extends Abstra
SubList.this.add(i, e);
cursor = i + 1;
lastRet = -1;
- expectedModCount = ArrayList.this.modCount;
+ expectedModCount = root.modCount;
} catch (IndexOutOfBoundsException ex) {
throw new ConcurrentModificationException();
}
}
final void checkForComodification() {
- if (expectedModCount != ArrayList.this.modCount)
+ if (root.modCount != expectedModCount)
throw new ConcurrentModificationException();
}
};
@@ -1069,12 +1242,7 @@ public class ArrayList extends Abstra
public List subList(int fromIndex, int toIndex) {
subListRangeCheck(fromIndex, toIndex, size);
- return new SubList(this, offset, fromIndex, toIndex);
- }
-
- private void rangeCheck(int index) {
- if (index < 0 || index >= this.size)
- throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
+ return new SubList<>(this, fromIndex, toIndex);
}
private void rangeCheckForAdd(int index) {
@@ -1087,8 +1255,303 @@ public class ArrayList extends Abstra
}
private void checkForComodification() {
- if (ArrayList.this.modCount != this.modCount)
+ 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 is not used because late-binding logic
+ // is different here
+ 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 ArrayListSpliterator trySplit() {
+ int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
+ // ArrayListSpliterator could be used here as the source is already bound
+ return (lo >= mid) ? null : // divide range in half unless too small
+ new ArrayListSpliterator<>(root, 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 (long) (getFence() - index);
+ }
+
+ public int characteristics() {
+ return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
+ }
+ };
+ }
+ }
+
+ @Override
+ public void forEach(Consumer action) {
+ Objects.requireNonNull(action);
+ final int expectedModCount = modCount;
+ @SuppressWarnings("unchecked")
+ final E[] elementData = (E[]) this.elementData;
+ final int size = this.size;
+ for (int i=0; modCount == expectedModCount && i < size; i++) {
+ action.accept(elementData[i]);
+ }
+ if (modCount != expectedModCount) {
+ throw new ConcurrentModificationException();
+ }
+ }
+
+ /**
+ * 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<>(this, 0, -1, 0);
+ }
+
+ /** Index-based split-by-two, lazily initialized Spliterator */
+ static 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 final ArrayList list;
+ 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
+
+ /** Create new spliterator covering the given range */
+ ArrayListSpliterator(ArrayList list, int origin, int fence,
+ int expectedModCount) {
+ this.list = list; // OK if null unless traversed
+ 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)
+ ArrayList lst;
+ if ((hi = fence) < 0) {
+ if ((lst = list) == null)
+ hi = fence = 0;
+ else {
+ expectedModCount = lst.modCount;
+ hi = fence = lst.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<>(list, 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)list.elementData[i];
+ action.accept(e);
+ if (list.modCount != expectedModCount)
+ throw new ConcurrentModificationException();
+ return true;
+ }
+ return false;
+ }
+
+ public void forEachRemaining(Consumer action) {
+ int i, hi, mc; // hoist accesses and checks from loop
+ ArrayList lst; Object[] a;
+ if (action == null)
+ throw new NullPointerException();
+ if ((lst = list) != null && (a = lst.elementData) != null) {
+ if ((hi = fence) < 0) {
+ mc = lst.modCount;
+ hi = lst.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 (long) (getFence() - index);
+ }
+
+ public int characteristics() {
+ return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
+ }
+ }
+
+ @Override
+ public boolean removeIf(Predicate filter) {
+ Objects.requireNonNull(filter);
+ final int expectedModCount = modCount;
+ final Object[] elementData = this.elementData;
+ int r = 0, w = 0, remaining = size, deleted = 0;
+ try {
+ for (; remaining > 0; remaining--, r++) {
+ @SuppressWarnings("unchecked") E e = (E) elementData[r];
+ if (filter.test(e))
+ deleted++;
+ else {
+ if (r != w)
+ elementData[w] = e;
+ w++;
+ }
+ }
+ if (modCount != expectedModCount)
+ throw new ConcurrentModificationException();
+ return deleted > 0;
+ } catch (Throwable ex) {
+ for (; remaining > 0; remaining--, r++, w++)
+ elementData[w] = elementData[r];
+ throw ex;
+ } finally {
+ if (deleted > 0) {
+ modCount++;
+ size -= deleted;
+ while (--deleted >= 0)
+ elementData[w++] = null;
+ }
+ }
+ }
+
+ @Override
+ @SuppressWarnings("unchecked")
+ public void replaceAll(UnaryOperator operator) {
+ Objects.requireNonNull(operator);
+ final int expectedModCount = modCount;
+ final int size = this.size;
+ for (int i=0; modCount == expectedModCount && i < size; i++) {
+ elementData[i] = operator.apply((E) elementData[i]);
+ }
+ if (modCount != expectedModCount) {
+ throw new ConcurrentModificationException();
+ }
+ modCount++;
+ }
+
+ @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++;
}
}