Iterator<Course> it = coursesToSelect.iterator();
六代目
2015-06-15 15:43
这个语句中的it是什么呢？是iterator的对象吗？iterator是一个接口，为什么能够声明it呢？
3回答
-
- 码农_鑫森淼焱垚
- 2015-09-01 09:58:22
对于集合来说,接口中的方法都是内部实现的,你可以查看AbstractList<E>中有相关声明
public Iterator<E> iterator() {
return new Itr();
}
private class Itr implements Iterator<E> {
/**
* Index of element to be returned by subsequent call to next.
*/
int cursor = 0;
/**
* Index of element returned by most recent call to next or
* previous. Reset to -1 if this element is deleted by a call
* to remove.
*/
int lastRet = -1;
/**
* The modCount value that the iterator believes that the backing
* List should have. If this expectation is violated, the iterator
* has detected concurrent modification.
*/
int expectedModCount = modCount;
public boolean hasNext() {
return cursor != size();
}
public E next() {
checkForComodification();
try {
int i = cursor;
E next = get(i);
lastRet = i;
cursor = i + 1;
return next;
} catch (IndexOutOfBoundsException e) {
checkForComodification();
throw new NoSuchElementException();
}
}
public void remove() {
if (lastRet < 0)
throw new IllegalStateException();
checkForComodification();
try {
AbstractList.this.remove(lastRet);
if (lastRet < cursor)
cursor--;
lastRet = -1;
expectedModCount = modCount;
} catch (IndexOutOfBoundsException e) {
throw new ConcurrentModificationException();
}
}
final void checkForComodification() {
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
}
}
简单来说,就是集合内部实现Iterator接口的方法,私有的
-
- RHZhunter
- 2015-07-25 20:31:09
coursesToSelect.iterator();?
-
- 康振宁
- 2015-06-15 17:22:46
是的。一样可以对象的
Java入门第三季
409792 学习 · 4340 问题
相似问题