合并清单项目 [英] combine items of list

问题描述

我有一个清单，可以说这些项目{30 50 5 60 90 5 80}我想做的是例如将第3个元素和第4个元素结合在一起并得到{30 50 65 90 5 80}

Hi I have a list with lets say these items {30 50 5 60 90 5 80} what I want to do is for example combine the 3rd and 4th element together and have {30 50 65 90 5 80}

你能告诉我我该怎么做吗?我正在使用Java链表类.

Could you tell me how would I do that? I am using the java linked list class.

推荐答案

public class Main {
    public static void main(String[] args) {
        List<Integer> list = new LinkedList<>();
        list.add(30);
        list.add(50);
        list.add(5);
        list.add(60);
        list.add(90);
        list.add(5);
        list.add(80);
        System.out.println(list);
        combine(list, 2, 3);
        System.out.println(list);
    }
    public static void combine(List<Integer> list, int indexA, int indexB) {
        Integer a = list.get(indexA);
        Integer b = list.get(indexB);
        list.remove(indexB); // [30, 50, 5, 90, 5, 80]
        list.add(indexA, a + b); // [30, 50, 65, 5, 90, 5, 80]
        list.remove(indexB); // [30, 50, 65, 90, 5, 80]
    }
}

输出为:

[30, 50, 5, 60, 90, 5, 80]
[30, 50, 65, 90, 5, 80]

您需要检查null值，以避免 NullPointerException

You need check nulls values for avoid NullPointerException

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