LinkedList中addAll(int index, Collection c)函数分析

 public boolean addAll(int index, Collection<? extends E> c) {
        if (index < 0 || index > size)
            throw new IndexOutOfBoundsException("Index: "+index+
                                                ", Size: "+size);
        Object[] a = c.toArray();
        int numNew = a.length;
        if (numNew==0)
            return false;
	modCount++;

        Entry<E> successor = (index==size ? header : entry(index));
        Entry<E> predecessor = successor.previous;
	for (int i=0; i<numNew; i++) {
            Entry<E> e = new Entry<E>((E)a[i], successor, predecessor);
            predecessor.next = e;
            predecessor = e;
        }
        successor.previous = predecessor;

        size += numNew;
        return true;
    }

这个函数也很无敌，关键是collection插入的时候保持了有序，主要是那个for循环体里面，后继的元素都在之前被插入的元素之后插入，所以能保持有序。