Arraylist源码注解

public class ArrayList extends AbstractList
        implements List, RandomAccess, Cloneable, java.io.Serializable
{
    private static final long serialVersionUID = 8683452581122892189L;      
    private static final int DEFAULT_CAPACITY = 10;      
    private static final Object[] EMPTY_ELEMENTDATA = {};      
    private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA = {};

    //Arraylist数据存储在此数组中
    transient Object[] elementData;
    //实际Arraylist存储数据的元素数量
    private int size;

    //构造函数
    public ArrayList(int initialCapacity) {
        //初始化成指定大小，initialCapacity指定
        if (initialCapacity > 0) {
            this.elementData = new Object[initialCapacity];
        } else if (initialCapacity == 0) {
            // 指定一个空数组,没有任何大小
            // private static final Object[] EMPTY_ELEMENTDATA = {};
            this.elementData = EMPTY_ELEMENTDATA;
        } else {
            throw new IllegalArgumentException("Illegal Capacity: "+
                    initialCapacity);
        }
    }      
    public ArrayList() {
        // 指定一个空数组,没有任何大小
        // private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA = {};
        this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
    }

    //传入一个集合
    public ArrayList(Collection c) {

        //变成一个含有此collection中所有元素的数组
        elementData = c.toArray();
        //若数组不为空
        if ((size = elementData.length) != 0) {
            //toArray没有返回objcet
            if (elementData.getClass() != Object[].class)
                //复制一下，变成一个含有相同元素同样长度的object类型数组
                elementData = Arrays.copyOf(elementData, size, Object[].class);
        } else {
            //数组为空
            this.elementData = EMPTY_ELEMENTDATA;
        }
    }

    //把数组的容量减少到它现在所拥有的元素个数
    public void trimToSize() {
        modCount++;
        if (size < elementData.length) {
            elementData = (size == 0)
                    ? EMPTY_ELEMENTDATA
                    : Arrays.copyOf(elementData, size);
        }
    }

    //当我们已经确定了要插入的对象的数目
    // 调用ensureCapacity来一次性扩容到可以容得下要插入的对象个数
    public void ensureCapacity(int minCapacity) {
        int minExpand = (elementData != DEFAULTCAPACITY_EMPTY_ELEMENTDATA)
                ?0:DEFAULT_CAPACITY;
        if (minCapacity > minExpand) {
            ensureExplicitCapacity(minCapacity);
        }
    }

    //add 方法调用ensureCapacityInternal(size + 1);
    private void ensureCapacityInternal(int minCapacity) {
        //如果数组为空，则设置当前数组的默认容量
        if (elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA) {
            //默认容量为：private static final int DEFAULT_CAPACITY = 10;
            //确认实际的容量，上面只是将minCapacity=10，这个方法就是真正的判断elementData是否够用
            minCapacity = Math.max(DEFAULT_CAPACITY, minCapacity);
        }         ensureExplicitCapacity(minCapacity);
    }

    //ensureCapacityInternal 方法调用ensureExplicitCapacity(minCapacity);
    private void ensureExplicitCapacity(int minCapacity) {
        modCount++;
        //当前容量>实际数组长度，说明不够用了，要扩容
        if (minCapacity - elementData.length > 0)
            grow(minCapacity);
    }

    //最大数组容量为Integer的最大值-8
    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;


    //ensureCapacityInternal 方法调用grow(minCapacity);
    private void grow(int minCapacity) {
        //先获取原容量
        int oldCapacity = elementData.length;
        //新容量，算法为 原容量=原容量+原容量/2
        int newCapacity = oldCapacity + (oldCapacity >> 1);
        //这句话就是适应于elementData就空数组的时候，length=0，那么oldCapacity=0，
        // newCapacity=0，所以这个判断成立，在这里就是真正的初始化elementData的大小了，
        // 就是为10.前面的工作都是准备工作。
        if (newCapacity - minCapacity < 0)
            newCapacity = minCapacity;
        //若新容量值大于最大数组长度，调用hugeCapacity
        if (newCapacity - MAX_ARRAY_SIZE > 0)
            newCapacity = hugeCapacity(minCapacity);
        //设置为新容量，然后复制过去
        elementData = Arrays.copyOf(elementData, newCapacity);
    }

    //新容量值大于最大数组长度时调用
    private static int hugeCapacity(int minCapacity) {
        //最低容量<0，说明发生了溢出
        if (minCapacity < 0) 
            throw new OutOfMemoryError();

        //如果最小容量已经超过了最大数组长度，就返回Integer的最大值
        return (minCapacity > MAX_ARRAY_SIZE) ?
                Integer.MAX_VALUE :
                MAX_ARRAY_SIZE;
    }
    //返回数组元素个数
    public int size() {
        return size;
    }
    //返回是否空
    public boolean isEmpty() {
        return size == 0;
    }
    //返回是否存在某元素
    public boolean contains(Object o) {
        return indexOf(o) >= 0;
    }
    //查找元素o的索引位置
    public int indexOf(Object o) {
        //如果o的null就查找第一个null并返回
        if (o == null) {
            for (int i = 0; i < size; i++)
                if (elementData[i]==null)
                    return i;
        } else {
            //o不是null，查找第一个位置并返回
            for (int i = 0; i < size; i++)
                if (o.equals(elementData[i]))
                    return i;
        }
        return -1;
    }

    //与indexOf相反，返回元素的倒数第一个位置
    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;
    }

//克隆集合
    public Object clone() {
        try {
            //直接调用父类的clone方法
            ArrayList v = (ArrayList) super.clone();
            //将elementData拷贝到v.elementData中
            v.elementData = Arrays.copyOf(elementData, size);
            v.modCount = 0;
            return v;
        } catch (CloneNotSupportedException e) {
 
            throw new InternalError(e);
        }
    }
    //获取集合的数组对象
    public Object[] toArray() {
        return Arrays.copyOf(elementData, size);
    }      
    @SuppressWarnings("unchecked")

    public  T[] toArray(T[] a) {
        if (a.length < size)
 
            return (T[]) Arrays.copyOf(elementData, size, a.getClass());
        System.arraycopy(elementData, 0, a, 0, size);
        if (a.length > size)
            a[size] = null;
        return a;
    }
    @SuppressWarnings("unchecked")

    E elementData(int index) {
        return (E) elementData[index];
    }

    public E get(int index) {
        rangeCheck(index);         return elementData(index);
    }      
    public E set(int index, E element) {
        rangeCheck(index);         E oldValue = elementData(index);
        elementData[index] = element;
        return oldValue;
    }      
    public boolean add(E e) {
        //先扩容
        //添加元素数据,为所存在的最大元素+1位置增加元素
        ensureCapacityInternal(size + 1); 
        elementData[size++] = e;
        return true;
    }      
    public void add(int index, E element) {
        //检查index也就是插入的位置是否合理
        rangeCheckForAdd(index);
        //先扩容
        //添加元素数据,为所存在的最大元素+1位置增加元素
        ensureCapacityInternal(size + 1);
        //这个方法就是用来在插入元素之后，要将index之后的元素都往后移一位，
        System.arraycopy(elementData, index, elementData, index + 1,
                size - index);
        //插入元素
        elementData[index] = element;
        //size增加1
        size++;
    }      
    public E remove(int index) {
        //检查index也就是删除 的位置是否合理
        rangeCheck(index);         modCount++;
        E oldValue = elementData(index);
        int numMoved = size - index - 1;
        //判断numMoved字段是不是最后一个元素，
        // 如果最后的元素直接把那个位置赋值为null，不进行数据搬移工作
        if (numMoved > 0)
            System.arraycopy(elementData, index+1, elementData, index,
                    numMoved);
        elementData[--size] = null;
        return oldValue;
    }
    //从前往后查找某元素并删除
    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;
                }
        }
        return false;
    }
    //与前面remove大致相同，不检查index合法性，因为是被remove(Object o)调用的
    private void fastRemove(int index) {
        modCount++;
        int numMoved = size - index - 1;
        if (numMoved > 0)
            System.arraycopy(elementData, index+1, elementData, index,
                    numMoved);
        elementData[--size] = null; 
    }      
    public void clear() {
        modCount++;  
        for (int i = 0; i < size; i++)
            elementData[i] = null;         size = 0;
    }
    //新数组元素加到当前数组末尾
    public boolean addAll(Collection c) {
        Object[] a = c.toArray();
        int numNew = a.length;
        ensureCapacityInternal(size + numNew); 
        System.arraycopy(a, 0, elementData, size, numNew);
        size += numNew;
        return numNew != 0;
    }
    //新数组元素插入到当前数组index位置
    public boolean addAll(int index, Collection c) {
        rangeCheckForAdd(index);
        Object[] a = c.toArray();
        int numNew = a.length;
        ensureCapacityInternal(size + numNew);          int numMoved = size - index;
        if (numMoved > 0)
            System.arraycopy(elementData, index, elementData, index + numNew,
                    numMoved);
        System.arraycopy(a, 0, elementData, index, numNew);
        size += numNew;
        return numNew != 0;
    }
    //删除指定范围的元素
    protected void removeRange(int fromIndex, int toIndex) {
        modCount++;
        int numMoved = size - toIndex;
        System.arraycopy(elementData, toIndex, elementData, fromIndex,
                numMoved);  
        int newSize = size - (toIndex-fromIndex);
        for (int i = newSize; i < size; i++) {
            elementData[i] = null;
        }
        size = newSize;
    }      
    private void rangeCheck(int index) {
        if (index >= size)
            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
    }      
    private void rangeCheckForAdd(int index) {
        if (index > size || index < 0)
            throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
    }      
    private String outOfBoundsMsg(int index) {
        return "Index: "+index+", Size: "+size;
    }      
    public boolean removeAll(Collection c) {
        Objects.requireNonNull(c);
        return batchRemove(c, false);
    }      
    public boolean retainAll(Collection c) {
        Objects.requireNonNull(c);
        return batchRemove(c, true);
    }     private boolean batchRemove(Collection c, boolean complement) {
        final Object[] elementData = this.elementData;
        int r = 0, w = 0;
        boolean modified = false;
        try {
            for (; r < size; r++)
                if (c.contains(elementData[r]) == complement)
                    elementData[w++] = elementData[r];
        } finally {
 
 
            if (r != size) {
                System.arraycopy(elementData, r,
                        elementData, w,
                        size - r);
                w += size - r;
            }
            if (w != size) {
 
                for (int i = w; i < size; i++)
                    elementData[i] = null;
                modCount += size - w;
                size = w;
                modified = true;
            }
        }
        return modified;
    }      
    private void writeObject(java.io.ObjectOutputStream s)
            throws java.io.IOException{
 
        int expectedModCount = modCount;
        s.defaultWriteObject();  
        s.writeInt(size);  
        for (int i=0; i 0) {
 
            ensureCapacityInternal(size);             Object[] a = elementData;
 
            for (int i=0; i listIterator(int index) {
        if (index < 0 || index > size)
            throw new IndexOutOfBoundsException("Index: "+index);
        return new ListItr(index);
    }      
    public ListIterator listIterator() {
        return new ListItr(0);
    }      
    public Iterator iterator() {
        return new Itr();
    }      
    private class Itr implements Iterator {
        int cursor; 
        int lastRet = -1; 
        int expectedModCount = modCount;
        ////判断是否还有下一个元素
        public boolean hasNext() {
            return cursor != size;
        }
        @SuppressWarnings("unchecked")
        ////获取下一个元素的值
        public E next() {
            checkForComodification();
            int i = cursor;
            //判断下标是否越界
            if (i >= size)
                throw new NoSuchElementException();
            Object[] elementData = ArrayList.this.elementData;
            //还是判断下标越界
            if (i >= elementData.length)
                throw new ConcurrentModificationException();
            cursor = i + 1;
            //返回元素，并且设置上一次返回元素的下标
            return (E) elementData[lastRet = i];
        }

        //删除掉上一次next的元素
        public void remove() {
            //判断是否执行过next
            if (lastRet < 0)
                throw new IllegalStateException();
            checkForComodification();
            try {
                ArrayList.this.remove(lastRet);
                ////要删除的下标
                cursor = lastRet;
                ////防止重复删除，将下标置为-1
                lastRet = -1;
                expectedModCount = modCount;
            } catch (IndexOutOfBoundsException ex) {
                throw new ConcurrentModificationException();
            }
        }         @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++]);
            }
 
            cursor = i;
            lastRet = i - 1;
            checkForComodification();
        }         final void checkForComodification() {
            if (modCount != expectedModCount)
                throw new ConcurrentModificationException();
        }
    }      
    private class ListItr extends Itr implements ListIterator {
        ListItr(int index) {
            super();
            cursor = index;
        }
        public boolean hasPrevious() {
            return cursor != 0;
        }
        public int nextIndex() {
            return cursor;
        }
        public int previousIndex() {
            return cursor - 1;
        }
        @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;
                ArrayList.this.add(i, e);
                cursor = i + 1;
                lastRet = -1;
                expectedModCount = modCount;
            } catch (IndexOutOfBoundsException ex) {
                throw new ConcurrentModificationException();
            }
        }
    }      
    public List subList(int fromIndex, int toIndex) {
        subListRangeCheck(fromIndex, toIndex, size);
        return new SubList(this, 0, 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 final int offset;
        int size;         SubList(AbstractList parent,
                int offset, int fromIndex, int toIndex) {
            this.parent = parent;
            this.parentOffset = fromIndex;
            this.offset = offset + fromIndex;
            this.size = toIndex - fromIndex;
            this.modCount = ArrayList.this.modCount;
        }         public E set(int index, E e) {
            rangeCheck(index);
            checkForComodification();
            E oldValue = ArrayList.this.elementData(offset + index);
            ArrayList.this.elementData[offset + index] = e;
            return oldValue;
        }         public E get(int index) {
            rangeCheck(index);
            checkForComodification();
            return ArrayList.this.elementData(offset + index);
        }         public int size() {
            checkForComodification();
            return this.size;
        }         public void add(int index, E e) {
            rangeCheckForAdd(index);
            checkForComodification();
            parent.add(parentOffset + index, e);
            this.modCount = parent.modCount;
            this.size++;
        }         public E remove(int index) {
            rangeCheck(index);
            checkForComodification();
            E result = parent.remove(parentOffset + index);
            this.modCount = parent.modCount;
            this.size--;
            return result;
        }         protected void removeRange(int fromIndex, int toIndex) {
            checkForComodification();
            parent.removeRange(parentOffset + fromIndex,
                    parentOffset + toIndex);
            this.modCount = parent.modCount;
            this.size -= toIndex - fromIndex;
        }         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();
            parent.addAll(parentOffset + index, c);
            this.modCount = parent.modCount;
            this.size += cSize;
            return true;
        }         public Iterator iterator() {
            return listIterator();
        }         public ListIterator listIterator(final int index) {
            checkForComodification();
            rangeCheckForAdd(index);
            final int offset = this.offset;             return new ListIterator() {
                int cursor = index;
                int lastRet = -1;
                int expectedModCount = ArrayList.this.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 = ArrayList.this.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 = ArrayList.this.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 = ArrayList.this.elementData;
                    if (offset + i >= elementData.length) {
                        throw new ConcurrentModificationException();
                    }
                    while (i != size && modCount == expectedModCount) {
                        consumer.accept((E) elementData[offset + (i++)]);
                    }
 
                    lastRet = cursor = i;
                    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 = ArrayList.this.modCount;
                    } catch (IndexOutOfBoundsException ex) {
                        throw new ConcurrentModificationException();
                    }
                }                 public void set(E e) {
                    if (lastRet < 0)
                        throw new IllegalStateException();
                    checkForComodification();                     try {
                        ArrayList.this.set(offset + lastRet, e);
                    } catch (IndexOutOfBoundsException ex) {
                        throw new ConcurrentModificationException();
                    }
                }                 public void add(E e) {
                    checkForComodification();                     try {
                        int i = cursor;
                        SubList.this.add(i, e);
                        cursor = i + 1;
                        lastRet = -1;
                        expectedModCount = ArrayList.this.modCount;
                    } catch (IndexOutOfBoundsException ex) {
                        throw new ConcurrentModificationException();
                    }
                }                 final void checkForComodification() {
                    if (expectedModCount != ArrayList.this.modCount)
                        throw new ConcurrentModificationException();
                }
            };
        }         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));
        }         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 (ArrayList.this.modCount != this.modCount)
                throw new ConcurrentModificationException();
        }         public Spliterator spliterator() {
            checkForComodification();
            return new ArrayListSpliterator(ArrayList.this, offset,
                    offset + this.size, this.modCount);
        }
    }     @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();
        }
    }      
    @Override
    public Spliterator spliterator() {
        return new ArrayListSpliterator<>(this, 0, -1, 0);
    }      
    static final class ArrayListSpliterator implements Spliterator {                   private final ArrayList list;
        private int index; 
        private int fence; 
        private int expectedModCount;           
        ArrayListSpliterator(ArrayList list, int origin, int fence,
                             int expectedModCount) {
            this.list = list; 
            this.index = origin;
            this.fence = fence;
            this.expectedModCount = expectedModCount;
        }         private int getFence() { 
            int hi; 
            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 : 
                    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; 
            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);
 
 
 
        int removeCount = 0;
        final BitSet removeSet = new BitSet(size);
        final int expectedModCount = modCount;
        final int size = this.size;
        for (int i=0; modCount == expectedModCount && i < size; i++) {
            @SuppressWarnings("unchecked")
            final E element = (E) elementData[i];
            if (filter.test(element)) {
                removeSet.set(i);
                removeCount++;
            }
        }
        if (modCount != expectedModCount) {
            throw new ConcurrentModificationException();
        }  
        final boolean anyToRemove = removeCount > 0;
        if (anyToRemove) {
            final int newSize = size - removeCount;
            for (int i=0, j=0; (i < size) && (j < newSize); i++, j++) {
                i = removeSet.nextClearBit(i);
                elementData[j] = elementData[i];
            }
            for (int k=newSize; k < size; k++) {
                elementData[k] = null; 
            }
            this.size = newSize;
            if (modCount != expectedModCount) {
                throw new ConcurrentModificationException();
            }
            modCount++;
        }         return anyToRemove;
    }     @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++;
    }
}