通过列表迭代器在子列表中添加元素

Question

我有一个包含元素的数组列表-

0, 100, 200, 300, 400, 500, 600, 700...

从主列表中获取子列表后，如果 next() 返回的元素是 400

，我将添加一个元素

public static void add(List<String> list){
    List<String> subList = list.subList(2, 7);// 200, 300, 400, 500, 600
    ListIterator<String> listIterator = subList.listIterator();

    while(listIterator.hasNext()) {

        String value = listIterator.next();

        if(value.equals("400")) {
            listIterator.add("399");
        }

    }
    System.out.println(subList);
}

子列表现在变成 -

[200, 300, 400, 399, 500, 600]

可见，元素 399 是 after 400.

doc 表示

Inserts the specified element into the list (optional operation). The element is inserted immediately before the element that would be returned by next()....

请说明。

Answer 1

Inserts the specified element into the list (optional operation). The element is inserted immediately before the element that would be returned by next()

这意味着该元素将被插入到 next 对 next() 的调用返回的元素之前（即对 next() 的调用发生在在对 listIterator.add("399") 的调用之后，而不是在它之前），即 500。因此新元素在 500 之前添加。

Answer 2

immediately before the element that would be returned by next()

此时 next 返回的元素是 500。

Answer 3

Inserts the specified element into the list (optional operation). The element is inserted immediately before the element that would be returned by next().

   public static void add(List<String> list){
        List<String> subList = list.subList(2, 7);// 200, 300, 400, 500, 600
        ListIterator<String> listIterator = subList.listIterator();

        while(listIterator.hasNext()) {

            String value = listIterator.next();

            if(value.equals("400")) {   //when this statement is executed next would return 400
 //399 will be inserted before next call to next() function , next call to next() function would return 500, so it will be inserted before 500*/
                listIterator.add("399");  
            }

        }
        System.out.println(subList);
    }

通过列表迭代器在子列表中添加元素

Adding an element in a sublist through a list iterator

java

arraylist

sublist

listiterator