迭代器上的 next() 方法如何工作?

2022-01-10 00:00:00 iterator java

我对迭代器上的 next() 方法有疑问.如果我将这行代码作为我的代码的一部分(使用 arrayOfStrings size = 4):

I have a doubt with the next() method on iterators. If I have as a part of my code this lines (with arrayOfStrings size = 4):

Iterator<String> it = arrayOfStrings.iterator(); //arrayOfString is ArrayList<String>

while(it.hasNext()) {
    String e = it.next();
    System.out.println(e);
}

在第一次迭代时，迭代器开始指向索引为 0 的元素?还是像索引-1"?

At the very first iteration, the iterator starts pointing to element with index 0? or like the "index -1" ?

我问是因为据我所知 next() 方法返回集合中的下一个元素.

I ask because as far as I know the next() method returns the next element in the collection.

所以，如果在第一次迭代中，当调用 next() 时迭代器从索引 0 开始，它会返回索引 1 处的元素，我将无法对索引为 0 的元素?

So, if at the very first iteration the iterator starts at index 0 when next() is invoked, it returns the element at index 1 and I won´t be able to do nothing with the element at index 0?

推荐答案

将 next 视为一个两步过程.首先它获取迭代器中的下一项，然后递增指针以指向下一项.因此，当您创建一个新的迭代器时，它会被初始化为返回列表中的第一项(索引 0).

Think of next as a two-step process. First it gets the next item in the iterator, then it increments the pointer to point to the next item. So, when you create a new iterator, it is initialized to return the first item (index 0) in your list.

相关文章