java如何连续删除list中的数据

java连续删除list中的数据

一个list列表中有40个数据，连续删除第20到30个数据。

错误示范

 public static void main(String[] args) {
        List list = new ArrayList<>();
        for(int i = 0; i < 40; i++ ){
            list.add(i);
        }
        for(int i = 20; i < 30; i++){
            list.remove(i);
        }
        StringBuilder stringBuilder = new StringBuilder();
        for(int element: list){
            stringBuilder.append(" " + element);
        }
        System.out.println("element =" + stringBuilder.toString() );

    }

element = 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 21 23 25 27 29 31 33 35 37 39

发现删除错了。

正确做法

1、使用迭代器

public static void main(String[] args) {
        List list = new ArrayList<>();
        for(int i = 0; i < 40; i++ ){
            list.add(i);
        }
        Iterator iterator = list.iterator();
        int removeIndex = -1;
        while (iterator.hasNext()){
            if(removeIndex >= 30){
                break;
            }
            ++removeIndex;

            if(removeIndex < 20){
                iterator.next();
                continue;
            }
            iterator.next();
            iterator.remove();
        }


        StringBuilder stringBuilder = new StringBuilder();
        for(int element: list){
            stringBuilder.append(" " + element);
        }
        System.out.println("element =" + stringBuilder.toString() );

    }

2、使用sublist

public static void main(String[] args) {
        List list = new ArrayList<>();
        for(int i = 0; i < 40; i++ ){
            list.add(i);
        }
        list.subList(20, 30).clear();


        StringBuilder stringBuilder = new StringBuilder();
        for(int element: list){
            stringBuilder.append(" " + element);
        }
        System.out.println("element =" + stringBuilder.toString() );

    }