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ArrayList简介：ArrayList是一个数组队列，相当于一个动态的数组，容量可以动态的增长；它继承了AbstractList并实现了List，RandomAccess，Cloneable、Serializable这些接口。
特性：
（1）ArrayList继承了AbstractList，实现了List，它是一个数组队列，提供了相关的添加、删除、修改、遍历等功能。
（2）ArrayList实现了RandomAccess接口，提供了随机访问功能，RandomAccess是Java中用来被List实现，为List提供快速访问功能的；还可以通过元素下标进行快速随机访问。
（3）ArrayList实现了Cloneable接口，覆盖了函数clone()，可以被克隆。
（4）ArrayList实现了Serializable接口，可以被序列化，通过网络传输。
（5）ArrayList不是线程安全的，建议在单线程中使用。
（6）ArrayList是使用elementData一个Object[] 数组来动态存储数据的。
ArrayList支持三种遍历方式：
（1）通过迭代器进行遍历，即通过Itreator去遍历
Integer value=null;Iterator iter=list.iterator();while(iter.hasNext()){ value=(Interger)iter.next();}
（2）随机访问模式，通过索引值去遍历所有元素
Interger value=null;int size=list.size();fo(int i=0;i<size;i++){ value=(Integer)list.get(i);}
（3）for循环遍历
Integer value=null;for(Integer inte : list){ value=inte;}
三种遍历方式中通过索引去遍历速度最快，通过迭代器去遍历速度最慢。
示例程序：
public class Hello {
public static void main(String[] args) {
ArrayList list = new ArrayList();list.add("1");list.add("2");list.add("3");list.add("4");list.add(0, "5");System.out.println("the first element is: "+ list.get(0));list.remove("3");System.out.println("Arraylist size=: "+ list.size());System.out.println("ArrayList contains 3 is: "+ list.contains(3));list.set(1, "10"); for(Iterator iter = list.iterator(); iter.hasNext(); ) { System.out.println("next is: "+ iter.next());} String[] arr = (String[])list.toArray(new String[0]); for (String str:arr) System.out.println("str: "+ str);list.clear();System.out.println("ArrayList is empty: "+ list.isEmpty());}}
运行结果：
the first element is: 5
Arraylist size=: 4
ArrayList contains 3 is: false
next is: 5
next is: 10
next is: 2
next is: 4
str: 5
str: 10
str: 2
str: 4
ArrayList is empty: true
ArrayList源代码分析：
// Arraylist继承了AbstractList 实现了List，RandomAccess，Cloneable，Serializable接口
public class ArrayList<E> extends AbstractList<E>implements List<E>, RandomAccess, Cloneable, java.io.Serializable{private static final long serialVersionUID = 8683452581122892189L; //序列化IDprivate static final int DEFAULT_CAPACITY = 10; //初始大小为10，会动态增加private static final Object[] EMPTY_ELEMENTDATA = {};//空的数组实例private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA = {}; transient Object[] elementData; // ArrayList用来存储对象的数组private int size;//数组中包含对象的个数//ArrayList构造函数，构造初始大小的elementDatapublic ArrayList(int initialCapacity) {if (initialCapacity > 0) {this.elementData = new Object[initialCapacity];} else if (initialCapacity == 0) {this.elementData = EMPTY_ELEMENTDATA;} else {throw new IllegalArgumentException("Illegal Capacity: "+ initialCapacity);} }//构造函数，初始化大小为10的数组public ArrayList() {this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;}//带有Collection的构造函数public ArrayList(Collection<? extends E> c) {elementData = c.toArray(); if ((size = elementData.length) != 0) {// c.toArray might (incorrectly) not return Object[] (see 6260652)if (elementData.getClass() != Object[].class)elementData = Arrays.copyOf(elementData, size, Object[].class);} else {// replace with empty array.this.elementData = EMPTY_ELEMENTDATA;} }//当前容量值设置为实际个数public void trimToSize() { modCount++; if (size < elementData.length) {elementData = (size == 0) ? EMPTY_ELEMENTDATA: Arrays.copyOf(elementData, size);} }//判断容量，容量不够增加public void ensureCapacity(int minCapacity) {int minExpand = (elementData != DEFAULTCAPACITY_EMPTY_ELEMENTDATA)// 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 void ensureCapacityInternal(int minCapacity) {if (elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA) { minCapacity = Math.max(DEFAULT_CAPACITY, minCapacity);}
ensureExplicitCapacity(minCapacity);}
private void ensureExplicitCapacity(int minCapacity) { modCount++;
// overflow-conscious codeif (minCapacity - elementData.length > 0) grow(minCapacity);}//最大的容量分配private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; private void grow(int minCapacity) {// overflow-conscious codeint oldCapacity = elementData.length; 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:elementData = Arrays.copyOf(elementData, newCapacity);}
private static int hugeCapacity(int minCapacity) {if (minCapacity < 0) // overflowthrow new OutOfMemoryError(); return (minCapacity > MAX_ARRAY_SIZE) ? Integer.MAX_VALUE :MAX_ARRAY_SIZE;}//返回ArrayList的大小public int size() {return size;}//判断ArrayList是否为空public boolean isEmpty() {return size == 0;}//判断是否含有某个对象public boolean contains(Object o) {return indexOf(o) >= 0;}//查找对象，返回坐标public int indexOf(Object o) {if (o == null) {for (int i = 0; i < size; i++)if (elementData[i]==null)return i;} else {for (int i = 0; i < size; i++)if (o.equals(elementData[i]))return i;}return -1;}//返回对象相同的最后一个坐标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;}//返回一个影子对象克隆public Object clone() {try { ArrayList<?> v = (ArrayList<?>) super.clone();v.elementData = Arrays.copyOf(elementData, size);v.modCount = 0; return v;} catch (CloneNotSupportedException e) {// this shouldn‘t happen, since we are Cloneablethrow new InternalError(e);} }//返回一个包含所有ArrayList元素的数组public Object[] toArray() {return Arrays.copyOf(elementData, size);}//返回泛型对象数组，一般使用这个不是上边那个@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(elementData, size, a.getClass());System.arraycopy(elementData, 0, a, 0, size); if (a.length > size) a[size] = null; return a;}//得到指定下标的对象@SuppressWarnings("unchecked")E elementData(int index) {return (E) elementData[index];}//得到指定下标的对象，并对下标进行判断public E get(int index) { rangeCheck(index);
return elementData(index);}//替换指定下标的对象，会检查下标并返回public E set(int index, E element) { rangeCheck(index);
E oldValue = elementData(index);elementData[index] = element; return oldValue;}//追加对象public boolean add(E e) { ensureCapacityInternal(size + 1); // Increments modCount!!elementData[size++] = e; return true;}//在指定的下标后增加对象public void add(int index, E element) { rangeCheckForAdd(index);
ensureCapacityInternal(size + 1); // Increments modCount!!System.arraycopy(elementData, index, elementData, index + 1,size - index);elementData[index] = element;size++;}//删除指定坐标的对象public E remove(int index) { rangeCheck(index);
modCount++;E oldValue = elementData(index);
int numMoved = size - index - 1; if (numMoved > 0) System.arraycopy(elementData, index+1, elementData, index,numMoved);elementData[--size] = null; // clear to let GC do its work
return oldValue;}// 删除ArrayList第一次出现的对象opublic 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;}//删除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; // clear to let GC do its work}//清空ArrayListpublic void clear() { modCount++;
// clear to let GC do its workfor (int i = 0; i < size; i++)elementData[i] = null;
size = 0;}//将集合C追加到ArrayList中public boolean addAll(Collection<? extends E> c) { Object[] a = c.toArray(); int numNew = a.length;ensureCapacityInternal(size + numNew); // Increments modCountSystem.arraycopy(a, 0, elementData, size, numNew);size += numNew; return numNew != 0;}//在ArrayList中的某个坐标后追加集合cpublic boolean addAll(int index, Collection<? extends E> c) { rangeCheckForAdd(index);
Object[] a = c.toArray(); int numNew = a.length;ensureCapacityInternal(size + numNew); // Increments modCountint 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;}//删除范围中的对象protected void removeRange(int fromIndex, int toIndex) { modCount++; int numMoved = size - toIndex;System.arraycopy(elementData, toIndex, elementData, fromIndex,numMoved);
// clear to let GC do its workint newSize = size - (toIndex-fromIndex); for (int i = newSize; i < size; i++) {elementData[i] = null;}size = newSize;}//范围检查private void rangeCheck(int index) {if (index >= size)throw new IndexOutOfBoundsException(outOfBoundsMsg(index));}//在添加或者添加所有的时候范围检查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);}//删除c中的在ArrayList中存在或者不存在的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 {// 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 workfor (int i = w; i < size; i++) elementData[i] = null;modCount += size - w;size = w;modified = true;} }return modified;}//序列化private void writeObject(java.io.ObjectOutputStream s)throws java.io.IOException{// Write out element count, and any hidden stuffint 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(elementData[i]);}
if (modCount != expectedModCount) {throw new ConcurrentModificationException();} }//反序列化private void readObject(java.io.ObjectInputStream s)throws java.io.IOException, ClassNotFoundException {elementData = EMPTY_ELEMENTDATA;// Read in size, and any hidden stuffs.defaultReadObject();// Read in capacitys.readInt(); // ignoredif (size > 0) {// be like clone(), allocate array based upon size not capacityensureCapacityInternal(size);Object[] a = elementData;// 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 ListItr(index);}public ListIterator<E> listIterator() {return new ListItr(0);}public Iterator<E> iterator() {return new Itr();}private class Itr implements Iterator<E> {int cursor; // index of next element to returnint lastRet = -1; // index of last element returned; -1 if no suchint expectedModCount = modCount;
public boolean hasNext() {return cursor != size;}
@SuppressWarnings("unchecked")public E next() { checkForComodification(); int i = cursor; if (i >= size)throw new NoSuchElementException();Object[] elementData = ArrayList.this.elementData; if (i >= elementData.length)throw new ConcurrentModificationException();cursor = i + 1; return (E) elementData[lastRet = i];}
public void remove() {if (lastRet < 0)throw new IllegalStateException();checkForComodification();
try { ArrayList.this.remove(lastRet);cursor = lastRet;lastRet = -1;expectedModCount = modCount;} catch (IndexOutOfBoundsException ex) {throw new ConcurrentModificationException();} }
@Override @SuppressWarnings("unchecked")public void forEachRemaining(Consumer<? super E> 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 trafficcursor = i;lastRet = i - 1;checkForComodification();}
final void checkForComodification() {if (modCount != expectedModCount)throw new ConcurrentModificationException();} }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 = 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<E> 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<E> implements RandomAccess {private final AbstractList<E> parent; private final int parentOffset; private final int offset; int size;
SubList(AbstractList<E> 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<? extends E> c) {return addAll(this.size, c);}
public boolean addAll(int index, Collection<? extends E> 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<E> iterator() {return listIterator();}
public ListIterator<E> listIterator(final int index) { checkForComodification();rangeCheckForAdd(index); final int offset = this.offset;
return new ListIterator<E>() {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<? super E> 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++)]);}// update once at end of iteration to reduce heap write trafficlastRet = 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<E> 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<E> spliterator() { checkForComodification(); return new ArrayListSpliterator<E>(ArrayList.this, offset,offset + this.size, this.modCount);} }
@Overridepublic void forEach(Consumer<? super E> 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();} }@Overridepublic Spliterator<E> spliterator() {return new ArrayListSpliterator<>(this, 0, -1, 0);}
/** Index-based split-by-two, lazily initialized Spliterator */static final class ArrayListSpliterator<E> implements Spliterator<E> {
private final ArrayList<E> list; private int index; // current index, modified on advance/splitprivate int fence; // -1 until used; then one past last indexprivate int expectedModCount; // initialized when fence set
/** Create new spliterator covering the given range */ArrayListSpliterator(ArrayList<E> list, int origin, int fence, int expectedModCount) {this.list = list; // OK if null unless traversedthis.index = origin; this.fence = fence; this.expectedModCount = expectedModCount;}
private int getFence() { // initialize fence to size on first useint hi; // (a specialized variant appears in method forEach)ArrayList<E> lst; if ((hi = fence) < 0) {if ((lst = list) == null) hi = fence = 0; else {expectedModCount = lst.modCount;hi = fence = lst.size;} }return hi;}
public ArrayListSpliterator<E> trySplit() {int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; return (lo >= mid) ? null : // divide range in half unless too smallnew ArrayListSpliterator<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.elementData[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 loopArrayList<E> 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;}elsemc = 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;} }
@Overridepublic 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 unmodifiedint 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();}// shift surviving elements left over the spaces left by removed elementsfinal 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; // 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++) {elementData[i] = operator.apply((E) elementData[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[]) elementData, 0, size, c); if (modCount != expectedModCount) {throw new ConcurrentModificationException();} modCount++;}}
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时间： 2024-10-31 18:51:00