Arraylist

ackage javabean.adt;

import sun.misc.SharedSecrets;

import java.util.*;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.UnaryOperator;

public class CopyLst<E>extends AbstractList<E>
        implements List<E>, RandomAccess, Cloneable, java.io.Serializable {


    private static final int DEFAULT_CAPACITY = 10;

    private static final Object[] intShuZu = {};


    private static final Object[] emptyShuZu = {};
    /**
     * Java的serialization提供了一种持久化对象实例的机制。
     * 当持久化对象时，可能有一个特殊的对象数据成员，
     * 我们不想用serialization机制来保存它。
     * 为了在一个特定对象的一个域上关闭serialization，
     * 可以在这个域前加上关键字transient。
     * 当一个对象被序列化的时候，transient型变量的值不包括在序列化的表示中，然而非transient型的变量是被包括进去的。
     */
    transient Object[] dongtaiShuzu; // non-private to simplify nested class access

    private int size;

    public CopyLst(int initialCapacity) {
        if (initialCapacity > 0) {
            this.dongtaiShuzu = new Object[initialCapacity];
        } else if (initialCapacity == 0) {
            this.dongtaiShuzu = intShuZu;
        } else {
            throw new IllegalArgumentException("Illegal Capacity: "+
                    initialCapacity);
        }
    }

    public CopyLst() {
        this.dongtaiShuzu = emptyShuZu;
    }


    public CopyLst(Collection<? extends E> c) {
        dongtaiShuzu = c.toArray();
        if ((size = dongtaiShuzu.length) != 0) {
            // c.toArray might (incorrectly) not return Object[] (see 6260652)
            if (dongtaiShuzu.getClass() != Object[].class)
                dongtaiShuzu = Arrays.copyOf(dongtaiShuzu, size, Object[].class);
        } else {
            // replace with empty array.
            this.dongtaiShuzu = intShuZu;
        }
    }


    public void trimToSize() {
        modCount++;
        if (size < dongtaiShuzu.length) {
            dongtaiShuzu = (size == 0)
                    ? intShuZu
                    : Arrays.copyOf(dongtaiShuzu, size);
        }
    }


    public void ensureCapacity(int minCapacity) {
        int minExpand = (dongtaiShuzu != emptyShuZu)
                // any size if not default element table
                ? 0
                // larger than default for default empty table. It's already
                // supposed to be at default size.
                : DEFAULT_CAPACITY;

        if (minCapacity > minExpand) {
            ensureExplicitCapacity(minCapacity);
        }
    }

    private static int calculateCapacity(Object[] elementData, int minCapacity) {
        if (elementData == emptyShuZu) {
            return Math.max(DEFAULT_CAPACITY, minCapacity);
        }
        return minCapacity;
    }

    private void addShuzuLegth(int minCapacity) {
        ensureExplicitCapacity(calculateCapacity(dongtaiShuzu, minCapacity));
    }

    private void ensureExplicitCapacity(int minCapacity) {
        modCount++;

        // overflow-conscious code
        if (minCapacity - dongtaiShuzu.length > 0)
            grow(minCapacity);
    }


    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;


    private void grow(int minCapacity) {
        // overflow-conscious code
        int oldCapacity = dongtaiShuzu.length;
        /**
         * <<      :     左移运算符，num << 1,相当于num乘以2
         *
         * >>      :     右移运算符，num >> 1,相当于num除以2
         *
         * >>>    :     无符号右移，忽略符号位，空位都以0补齐
         */
        int newCapacity = oldCapacity + (oldCapacity >> 1);
        if (newCapacity - minCapacity < 0)
            newCapacity = minCapacity;
        if (newCapacity - MAX_ARRAY_SIZE > 0)
            newCapacity = hugeCapacity(minCapacity);
        // minCapacity is usually close to size, so this is a win:
        dongtaiShuzu = Arrays.copyOf(dongtaiShuzu, newCapacity);
    }

    private static int hugeCapacity(int minCapacity) {
        if (minCapacity < 0) // overflow
            throw new OutOfMemoryError();
        return (minCapacity > MAX_ARRAY_SIZE) ?
                Integer.MAX_VALUE :
                MAX_ARRAY_SIZE;
    }

    public int size() {
        return size;
    }


    public boolean isEmpty() {
        return size == 0;
    }


    public boolean contains(Object o) {
        return indexOf(o) >= 0;
    }


    public int indexOf(Object o) {
        if (o == null) {
            for (int i = 0; i < size; i++)
                if (dongtaiShuzu[i]==null)
                    return i;
        } else {
            for (int i = 0; i < size; i++)
                if (o.equals(dongtaiShuzu[i]))
                    return i;
        }
        return -1;
    }


    public int lastIndexOf(Object o) {
        if (o == null) {
            for (int i = size-1; i >= 0; i--)
                if (dongtaiShuzu[i]==null)
                    return i;
        } else {
            for (int i = size-1; i >= 0; i--)
                if (o.equals(dongtaiShuzu[i]))
                    return i;
        }
        return -1;
    }


    public Object clone() {
        try {
            CopyLst<?> v = ( CopyLst<?>) super.clone();
            v.dongtaiShuzu = Arrays.copyOf(dongtaiShuzu, size);
            v.modCount = 0;
            return v;
        } catch (CloneNotSupportedException e) {
            // this shouldn't happen, since we are Cloneable
            throw new InternalError(e);
        }
    }


    public Object[] toArray() {
        return Arrays.copyOf(dongtaiShuzu, size);
    }


    @SuppressWarnings("unchecked")
    public <T> T[] toArray(T[] a) {
        if (a.length < size)
            // Make a new array of a's runtime type, but my contents:
            return (T[]) Arrays.copyOf(dongtaiShuzu, size, a.getClass());
        System.arraycopy(dongtaiShuzu, 0, a, 0, size);
        if (a.length > size)
            a[size] = null;
        return a;
    }

    // Positional Access Operations

    @SuppressWarnings("unchecked")
    E elementData(int index) {
        return (E) dongtaiShuzu[index];
    }


    public E get(int index) {
        rangeCheck(index);

        return elementData(index);
    }

    public E set(int index, E element) {
        rangeCheck(index);

        E oldValue = elementData(index);
        dongtaiShuzu[index] = element;
        return oldValue;
    }


    public boolean add(E e) {
        addShuzuLegth(size + 1);  // Increments modCount!!
        dongtaiShuzu[size++] = e;
        return true;
    }


    public void add(int index, E element) {
        rangeCheckForAdd(index);

        addShuzuLegth(size + 1);  // Increments modCount!!
        System.arraycopy(dongtaiShuzu, index, dongtaiShuzu, index + 1,
                size - index);
        dongtaiShuzu[index] = element;
        size++;
    }


    public E remove(int index) {
        rangeCheck(index);
        //为了统计 对于dongtaiShuzu的操作次数，其实多线程访问的额时候 也没用

        modCount++;
        E oldValue = elementData(index);
        //String [] a =  {"1","2","3",""}}
        // size = 3
        // remove 1;
        // numMoved = 3- 1-1 = 1;
        int numMoved = size - index - 1;
        if (numMoved > 0)
            System.arraycopy(dongtaiShuzu, index+1, dongtaiShuzu, index,
                    numMoved);
        dongtaiShuzu[--size] = null; // clear to let GC do its work

        return oldValue;
    }


    public boolean remove(Object o) {
        if (o == null) {
            for (int index = 0; index < size; index++)
                if (dongtaiShuzu[index] == null) {
                    fastRemove(index);
                    return true;
                }
        } else {
            for (int index = 0; index < size; index++)
                if (o.equals(dongtaiShuzu[index])) {
                    fastRemove(index);
                    return true;
                }
        }
        return false;
    }

    /*
     * Private remove method that skips bounds checking and does not
     * return the value removed.
     */
    private void fastRemove(int index) {
        modCount++;
        int numMoved = size - index - 1;
        if (numMoved > 0)
            System.arraycopy(dongtaiShuzu, index+1, dongtaiShuzu, index,
                    numMoved);
        dongtaiShuzu[--size] = null; // clear to let GC do its work
    }


    public void clear() {
        modCount++;

        // clear to let GC do its work
        for (int i = 0; i < size; i++)
            dongtaiShuzu[i] = null;

        size = 0;
    }


    public boolean addAll(Collection<? extends E> c) {
        Object[] a = c.toArray();
        int numNew = a.length;
        addShuzuLegth(size + numNew);  // Increments modCount
        System.arraycopy(a, 0, dongtaiShuzu, size, numNew);
        size += numNew;
        return numNew != 0;
    }


    public boolean addAll(int index, Collection<? extends E> c) {
        rangeCheckForAdd(index);

        Object[] a = c.toArray();
        int numNew = a.length;
        addShuzuLegth(size + numNew);  // Increments modCount

        int numMoved = size - index;
        if (numMoved > 0)
            System.arraycopy(dongtaiShuzu, index, dongtaiShuzu, index + numNew,
                    numMoved);

        System.arraycopy(a, 0, dongtaiShuzu, index, numNew);
        size += numNew;
        return numNew != 0;
    }


    protected void removeRange(int fromIndex, int toIndex) {
        modCount++;
        int numMoved = size - toIndex;
        System.arraycopy(dongtaiShuzu, toIndex, dongtaiShuzu, fromIndex,
                numMoved);

        // clear to let GC do its work
        int newSize = size - (toIndex-fromIndex);
        for (int i = newSize; i < size; i++) {
            dongtaiShuzu[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.dongtaiShuzu;
        int r = 0, w = 0;
        boolean modified = false;
        try {
            for (; r < size; r++)
                if (c.contains(elementData[r]) == complement)
                    elementData[w++] = elementData[r];
        } finally {
            // Preserve behavioral compatibility with AbstractCollection,
            // even if c.contains() throws.
            if (r != size) {
                System.arraycopy(elementData, r,
                        elementData, w,
                        size - r);
                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;
                size = w;
                modified = true;
            }
        }
        return modified;
    }


    private void writeObject(java.io.ObjectOutputStream s)
            throws java.io.IOException{
        // Write out element count, and any hidden stuff
        int expectedModCount = modCount;
        s.defaultWriteObject();

        // 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; i<size; i++) {
            s.writeObject(dongtaiShuzu[i]);
        }

        if (modCount != expectedModCount) {
            throw new ConcurrentModificationException();
        }
    }


    private void readObject(java.io.ObjectInputStream s)
            throws java.io.IOException, ClassNotFoundException {
        dongtaiShuzu = intShuZu;

        // Read in size, and any hidden stuff
        s.defaultReadObject();

        // Read in capacity
        s.readInt(); // ignored

        if (size > 0) {
            // be like clone(), allocate array based upon size not capacity
            int capacity = calculateCapacity(dongtaiShuzu, size);
            SharedSecrets.getJavaOISAccess().checkArray(s, Object[].class, capacity);
            addShuzuLegth(size);

            Object[] a = dongtaiShuzu;
            // Read in all elements in the proper order.
            for (int i=0; i<size; i++) {
                a[i] = s.readObject();
            }
        }
    }


    public ListIterator<E> listIterator(int index) {
        if (index < 0 || index > size)
            throw new IndexOutOfBoundsException("Index: "+index);
        return new CopyLst.ListItr(index);
    }


    public ListIterator<E> listIterator() {
        return new CopyLst.ListItr(0);
    }


    public Iterator<E> iterator() {
        return new CopyLst.Itr();
    }

    private class Itr implements Iterator<E>{
        int cursor;       // index of next element to return
        int lastRet = -1; // index of last element returned; -1 if no such
        int expectedModCount = modCount;

        Itr() {}

        public boolean hasNext() {
            return cursor != size;
        }


        public E next() {
            checkForComodification();
            int i = cursor;
            if (i >= size)
                throw new NoSuchElementException();
            Object[] elementData = CopyLst.this.dongtaiShuzu;
            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 {
                CopyLst.this.remove(lastRet);
                cursor = lastRet;
                lastRet = -1;
                expectedModCount = modCount;
            } catch (IndexOutOfBoundsException ex) {
                throw new ConcurrentModificationException();
            }
        }

        @Override
        public void forEachRemaining(Consumer<? super E> consumer) {
            Objects.requireNonNull(consumer);
            final int size = CopyLst.this.size;
            int i = cursor;
            if (i >= size) {
                return;
            }
            final Object[] elementData = CopyLst.this.dongtaiShuzu;
            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();
        }

        /**
         * 为了防止在 遍历的时候 原数组被改动，在使用Iterator 迭代时 不可以对原数组进行操作
         */
        final void checkForComodification() {
            if (modCount != expectedModCount)
                throw new ConcurrentModificationException();
        }
    }

    /**
     * An optimized version of AbstractList.ListItr
     */
    private class ListItr extends Itr implements ListIterator<E> {
        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 = CopyLst
                    .this.dongtaiShuzu;
            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 {
                CopyLst.this.set(lastRet, e);
            } catch (IndexOutOfBoundsException ex) {
                throw new ConcurrentModificationException();
            }
        }

        public void add(E e) {
            checkForComodification();

            try {
                int i = cursor;
                CopyLst.this.add(i, e);
                cursor = i + 1;
                lastRet = -1;
                expectedModCount = modCount;
            } catch (IndexOutOfBoundsException ex) {
                throw new ConcurrentModificationException();
            }
        }
    }



    /*public List<E> subList(int fromIndex, int toIndex) {
        subListRangeCheck(fromIndex, toIndex, size);
        return new CopyLst.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 + ")");
    }

    @Override
    public void forEach(Consumer<? super E> action) {
        Objects.requireNonNull(action);
        final int expectedModCount = modCount;
        @SuppressWarnings("unchecked")
        final E[] elementData = (E[]) this.dongtaiShuzu;
        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<E> spliterator() {
        return new CopyLst.CopyLstSpliterator<>(this, 0, -1, 0);
    }


    static final class CopyLstSpliterator<E> implements Spliterator<E> {


        private final CopyLst<E> 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 */
        CopyLstSpliterator(CopyLst<E> 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)
            CopyLst<E> lst;
            if ((hi = fence) < 0) {
                if ((lst = list) == null)
                    hi = fence = 0;
                else {
                    expectedModCount = lst.modCount;
                    hi = fence = lst.size;
                }
            }
            return hi;
        }

        public CopyLst.CopyLstSpliterator<E> trySplit() {
            int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
            return (lo >= mid) ? null : // divide range in half unless too small
                    new CopyLst.CopyLstSpliterator<E>(list, lo, index = mid,
                            expectedModCount);
        }

        public boolean tryAdvance(Consumer<? super E> action) {
            if (action == null)
                throw new NullPointerException();
            int hi = getFence(), i = index;
            if (i < hi) {
                index = i + 1;
                @SuppressWarnings("unchecked") E e = (E)list.dongtaiShuzu[i];
                action.accept(e);
                if (list.modCount != expectedModCount)
                    throw new ConcurrentModificationException();
                return true;
            }
            return false;
        }

        public void forEachRemaining(Consumer<? super E> action) {
            int i, hi, mc; // hoist accesses and checks from loop
           CopyLst<E> lst; Object[] a;
            if (action == null)
                throw new NullPointerException();
            if ((lst = list) != null && (a = lst.dongtaiShuzu) != 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<? super E> filter) {
        Objects.requireNonNull(filter);
        // figure out which elements are to be removed
        // any exception thrown from the filter predicate at this stage
        // will leave the collection unmodified
        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) dongtaiShuzu[i];
            if (filter.test(element)) {
                removeSet.set(i);
                removeCount++;
            }
        }
        if (modCount != expectedModCount) {
            throw new ConcurrentModificationException();
        }

        // shift surviving elements left over the spaces left by removed elements
        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);
                dongtaiShuzu[j] = dongtaiShuzu[i];
            }
            for (int k=newSize; k < size; k++) {
                dongtaiShuzu[k] = null;  // Let gc do its work
            }
            this.size = newSize;
            if (modCount != expectedModCount) {
                throw new ConcurrentModificationException();
            }
            modCount++;
        }

        return anyToRemove;
    }

    @Override
    @SuppressWarnings("unchecked")
    public void replaceAll(UnaryOperator<E> operator) {
        Objects.requireNonNull(operator);
        final int expectedModCount = modCount;
        final int size = this.size;
        for (int i=0; modCount == expectedModCount && i < size; i++) {
            dongtaiShuzu[i] = operator.apply((E) dongtaiShuzu[i]);
        }
        if (modCount != expectedModCount) {
            throw new ConcurrentModificationException();
        }
        modCount++;
    }

    @Override
    @SuppressWarnings("unchecked")
    public void sort(Comparator<? super E> c) {
        final int expectedModCount = modCount;
        Arrays.sort((E[]) dongtaiShuzu, 0, size, c);
        if (modCount != expectedModCount) {
            throw new ConcurrentModificationException();
        }
        modCount++;
    }
}