1 private static final long serialVersionUID = 8683452581122892189L;
 2 
 3     /**
 4      * Default initial capacity.
 5      */
 6     private static final int DEFAULT_CAPACITY = 10;
 7 
 8     /**
 9      * Shared empty array instance used for empty instances.
10      */
11     private static final Object[] EMPTY_ELEMENTDATA =http://www.mamicode.com/ {};
12 
13     /**
14      * The array buffer into which the elements of the ArrayList are stored.
15      * The capacity of the ArrayList is the length of this array buffer. Any
16      * empty ArrayList with elementData =http://www.mamicode.com/= EMPTY_ELEMENTDATA will be expanded to>17      * DEFAULT_CAPACITY when the first element is added.
18      */
19     private transient Object[] elementData;
20 
21     /**
22      * The size of the ArrayList (the number of elements it contains).
23      *
24      * @serial
25      */
26     private int size;

 1  /**
 2      * The array buffer into which the components of the vector are
 3      * stored. The capacity of the vector is the length of this array buffer,
 4      * and is at least large enough to contain all the vector‘s elements.
 5      *
 6      * <p>Any array elements following the last element in the Vector are null.
 7      *
 8      * @serial
 9      */
10     protected Object[] elementData;
11 
12     /**
13      * The number of valid components in this {@code Vector} object.
14      * Components {@code elementData[0]} through
15      * {@code elementData[elementCount-1]} are the actual items.
16      *
17      * @serial
18      */
19     protected int elementCount;
20 
21     /**
22      * The amount by which the capacity of the vector is automatically
23      * incremented when its size becomes greater than its capacity.  If
24      * the capacity increment is less than or equal to zero, the capacity
25      * of the vector is doubled each time it needs to grow.
26      *
27      * @serial
28      */
29     protected int capacityIncrement;

 1  /**
 2      * The maximum size of array to allocate.
 3      * Some VMs reserve some header words in an array.
 4      * Attempts to allocate larger arrays may result in
 5      * OutOfMemoryError: Requested array size exceeds VM limit
 6      */
 7     private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
 8 
 9     private void grow(int minCapacity) {
10         // overflow-conscious code
11         int oldCapacity = elementData.length;
12         int newCapacity = oldCapacity + ((capacityIncrement > 0) ?
13                                          capacityIncrement : oldCapacity);
14         if (newCapacity - minCapacity < 0)
15             newCapacity = minCapacity;
16         if (newCapacity - MAX_ARRAY_SIZE > 0)
17             newCapacity = hugeCapacity(minCapacity);
18         elementData =http://www.mamicode.com/ Arrays.copyOf(elementData, newCapacity);
19     }

 1  public Vector(int initialCapacity, int capacityIncrement) {
 2         super();
 3         if (initialCapacity < 0)
 4             throw new IllegalArgumentException("Illegal Capacity: "+
 5                                                initialCapacity);
 6         this.elementData = http://www.mamicode.com/new Object[initialCapacity];
 7         this.capacityIncrement = capacityIncrement;
 8     }
 9 
10     /**
11      * Constructs an empty vector with the specified initial capacity and
12      * with its capacity increment equal to zero.
13      *
14      * @param   initialCapacity   the initial capacity of the vector
15      * @throws IllegalArgumentException if the specified initial capacity
16      *         is negative
17      */
18     public Vector(int initialCapacity) {
19         this(initialCapacity, 0);
20     }
21 
22     /**
23      * Constructs an empty vector so that its internal data array
24      * has size {@code 10} and its standard capacity increment is
25      * zero.
26      */
27     public Vector() {
28         this(10);
29     }

 1 /**
 2      * Increases the capacity to ensure that it can hold at least the
 3      * number of elements specified by the minimum capacity argument.
 4      *
 5      * @param minCapacity the desired minimum capacity
 6      */
 7     private void grow(int minCapacity) {
 8         // overflow-conscious code
 9         int oldCapacity = elementData.length;
10         int newCapacity = oldCapacity + (oldCapacity >> 1);　　//看这里
11         if (newCapacity - minCapacity < 0)
12             newCapacity = minCapacity;
13         if (newCapacity - MAX_ARRAY_SIZE > 0)
14             newCapacity = hugeCapacity(minCapacity);
15         // minCapacity is usually close to size, so this is a win:
16         elementData =http://www.mamicode.com/ Arrays.copyOf(elementData, newCapacity);
17     }

 
 1 public synchronized void insertElementAt(E obj, int index) {
 2         modCount++;
 3         if (index > elementCount) {
 4             throw new ArrayIndexOutOfBoundsException(index
 5                                                      + " > " + elementCount);
 6         }
 7         ensureCapacityHelper(elementCount + 1);
 8         System.arraycopy(elementData, index, elementData, index + 1, elementCount - index);
 9         elementData[index] = obj;
10         elementCount++;
11     }

1 public void trimToSize() {
2         modCount++;
3         if (size < elementData.length) {
4             elementData =http://www.mamicode.com/ Arrays.copyOf(elementData, size);
5         }
6     }

 1 public synchronized void setSize(int newSize) {
 2         modCount++;
 3         if (newSize > elementCount) {
 4             ensureCapacityHelper(newSize);
 5         } else {
 6             for (int i = newSize ; i < elementCount ; i++) {
 7                 elementData[i] = null;
 8             }
 9         }
10         elementCount = newSize;
11     }