1 package java.util;
  2 
  3 public class ArrayList<E> extends AbstractList<E>
  4         implements List<E>, RandomAccess, Cloneable, java.io.Serializable
  5 {
  6 
  7     ...
  8 
  9     // list中容量變化時，對應的同步函式
 10     public void ensureCapacity(int minCapacity) {
 11
 
         modCount++;
 12         int oldCapacity = elementData.length;
 13         if (minCapacity > oldCapacity) {
 14             Object oldData[] = elementData;
 15             int newCapacity = (oldCapacity * 3)/2 + 1;
 16             if (newCapacity < minCapacity)
 17                 newCapacity = minCapacity;
 
 18             // minCapacity is usually close to size, so this is a win:
 19             elementData = Arrays.copyOf(elementData, newCapacity);
 20         }
 21     }
 22 
 23 
 24     // 新增元素到佇列最後
 25     public boolean add(E e) {
 26         // 修改modCount
 27         ensureCapacity(size + 1);  //
 
 Increments modCount!!
 28         elementData[size++] = e;
 29         return true;
 30     }
 31 
 32 
 33     // 新增元素到指定的位置
 34     public void add(int index, E element) {
 35         if (index > size || index < 0)
 36             throw new IndexOutOfBoundsException(
 37             "Index: "+index+", Size: "+size);
 38 
 39         // 修改modCount
 40         ensureCapacity(size+1);  // Increments modCount!!
 41         System.arraycopy(elementData, index, elementData, index + 1,
 42              size - index);
 43         elementData[index] = element;
 44         size++;
 45     }
 46 
 47     // 新增集合
 48     public boolean addAll(Collection<? extends E> c) {
 49         Object[] a = c.toArray();
 50         int numNew = a.length;
 51         // 修改modCount
 52         ensureCapacity(size + numNew);  // Increments modCount
 53         System.arraycopy(a, 0, elementData, size, numNew);
 54         size += numNew;
 55         return numNew != 0;
 56     }
 57    
 58 
 59     // 刪除指定位置的元素 
 60     public E remove(int index) {
 61         RangeCheck(index);
 62 
 63         // 修改modCount
 64         modCount++;
 65         E oldValue = (E) elementData[index];
 66 
 67         int numMoved = size - index - 1;
 68         if (numMoved > 0)
 69             System.arraycopy(elementData, index+1, elementData, index, numMoved);
 70         elementData[--size] = null; // Let gc do its work
 71 
 72         return oldValue;
 73     }
 74 
 75 
 76     // 快速刪除指定位置的元素 
 77     private void fastRemove(int index) {
 78 
 79         // 修改modCount
 80         modCount++;
 81         int numMoved = size - index - 1;
 82         if (numMoved > 0)
 83             System.arraycopy(elementData, index+1, elementData, index,
 84                              numMoved);
 85         elementData[--size] = null; // Let gc do its work
 86     }
 87 
 88     // 清空集合
 89     public void clear() {
 90         // 修改modCount
 91         modCount++;
 92 
 93         // Let gc do its work
 94         for (int i = 0; i < size; i++)
 95             elementData[i] = null;
 96 
 97         size = 0;
 98     }
 99 
100     ...
101 }