Javaディエバソース解析

 1  private class Itr implements Iterator {
 2         int cursor;       //   next          
 3         int lastRet = -1; //       next          （       next  ，     -1）
 4         int expectedModCount = modCount;
 5 
 6         Itr() {}
 7 
 8         /*
 9         *               ，                  。
10         */
11         public boolean hasNext() {
12             return cursor != size;
13         }
14 
15         /*
16         *           ，      。
17         */
18         @SuppressWarnings("unchecked")
19         public E next() {
20             checkForComodification();
21             //1、    next        hasNext      ——      
22             int i = cursor;
23             if (i >= size)
24                 throw new NoSuchElementException();
25             Object[] elementData = ArrayList.this.elementData;
26             if (i >= elementData.length)
27                 throw new ConcurrentModificationException();
28             //2、     ，     
29             cursor = i + 1;
30             //3、lastRest                  
31             return (E) elementData[lastRet = i];
32         }
33 
34         public void remove() {
35             if (lastRet < 0)
36                 throw new IllegalStateException();
37             checkForComodification();
38 
39             try {
40                 //2、       ，remove           next       。
41                 ArrayList.this.remove(lastRet);
42                 cursor = lastRet;
43                 //3、       ，remove   next        。
44                 //     next      remove  ，remove        ，
45                 //     remove       next  。
46                 lastRet = -1;
47                 expectedModCount = modCount;
48             } catch (IndexOutOfBoundsException ex) {
49                 throw new ConcurrentModificationException();
50             }
51         }
52 
53         @Override
54         @SuppressWarnings("unchecked")
55         public void forEachRemaining(Consumer super E> consumer) {
56             Objects.requireNonNull(consumer);
57             final int size = ArrayList.this.size;
58             int i = cursor;
59             if (i >= size) {
60                 return;
61             }
62             final Object[] elementData = ArrayList.this.elementData;
63             if (i >= elementData.length) {
64                 throw new ConcurrentModificationException();
65             }
66             while (i != size && modCount == expectedModCount) {
67                 consumer.accept((E) elementData[i++]);
68             }
69             // update once at end of iteration to reduce heap write traffic
70             cursor = i;
71             lastRet = i - 1;
72             checkForComodification();
73         }
74 
75         final void checkForComodification() {
76             if (modCount != expectedModCount)
77                 throw new ConcurrentModificationException();
78         }
79     }