JAVA 集合类

 1     /**
 2      * Default initial capacity.
 3      */
 4     private static final int DEFAULT_CAPACITY = 10;
 5 
 6     public ArrayList(int initialCapacity) {
 7         super();
 8         if (initialCapacity < 0)
 9             throw new IllegalArgumentException("Illegal Capacity: "+
10                                                initialCapacity);
11         this.elementData = new Object[initialCapacity];
12     }
13 
14     public ArrayList() {
15         super();
16         this.elementData = EMPTY_ELEMENTDATA;
17     }
18 
19     public ArrayList(Collection<? extends E> c) {
20         elementData = c.toArray();
21         size = elementData.length;
22         // c.toArray might (incorrectly) not return Object[] (see 6260652)
23         if (elementData.getClass() != Object[].class)
24             elementData = Arrays.copyOf(elementData, size, Object[].class);
25     }
26     
27     public boolean add(E e) {
28         ensureCapacityInternal(size + 1);  // Increments modCount!!
29         elementData[size++] = e;
30         return true;
31     }
32 
33     public E get(int index) {
34         rangeCheck(index);
35 
36         return elementData(index);
37     }