两个list合并的算法

今天药忘吃喽~ 2022-04-23 06:42 207阅读 0赞

valueList

![20190124173419381.png][]

timeList

![20190124173454512.png][]

根据两个list比对获取这样的数据

以timeList为基准，把valueList的值合并到新的List，valueList中没有的值设为0

![20190124173526787.png][]

public class ComOrder {
    
        private List<Map<String, Integer>> valueList = new ArrayList<Map<String, Integer>>();
        private List<String> timeList = new ArrayList<String>();
    
        public ComOrder() {
            init();
        }
    
        /**
         * 数据初始化
         */
        private void init() {
            Map<String, Integer> map = new HashMap<String, Integer>();
            map.put("2019-01-21", 5);
            valueList.add(map);
    
            map = new HashMap<String, Integer>();
            map.put("2019-01-21", 3);
            valueList.add(map);
    
            map = new HashMap<String, Integer>();
            map.put("2019-01-21", 1);
            valueList.add(map);
    
            map = new HashMap<String, Integer>();
            map.put("2019-01-21", 4);
            valueList.add(map);
    
            map = new HashMap<String, Integer>();
            map.put("2019-01-22", 2);
            valueList.add(map);
    
            map = new HashMap<String, Integer>();
            map.put("2019-01-22", 5);
            valueList.add(map);
    
            map = new HashMap<String, Integer>();
            map.put("2019-01-22", 1);
            valueList.add(map);
    
            timeList.add("2019-01-21");
            timeList.add("2019-01-22");
            timeList.add("2019-01-23");
            timeList.add("2019-01-24");
            timeList.add("2019-01-25");
            timeList.add("2019-01-26");
            timeList.add("2019-01-27");
        }
    
        /**
         * 合并排序
         * @return
         */
        public List comp() {
            List<Map<String, Integer>> targetList = new ArrayList<Map<String, Integer>>();   //最后合并的list
            while (!valueList.isEmpty()) {
                for (String s: timeList) {      //遍历timelist,timelist的每个key都不能在一轮循环中丢失
                    Integer v = 0;               //日期对应的值，默认为0
                    for (Map<String, Integer> map : valueList) {
                        if (map.containsKey(s)) {//取得日期对应的值
                            v = map.get(s);      //给v赋值，循环外添加到map，list中
                            valueList.remove(map);//valueList清除刚才找到的map，避免死循环且重复计算
                            break;                //找到对应值，退出循环
                        }
                    }
                    Map<String, Integer> map = new HashMap<String, Integer>();
                    map.put(s, v);
                    targetList.add(map);
                }
            }
    
            return targetList;
        }
    
        /**
         * 打印
         * @param list
         */
        public void print(List<Map<String, Integer>> list) {
            for (Map<String, Integer> map : list) {
                Set<Map.Entry<String, Integer>> entries = map.entrySet();
                for (Map.Entry<String, Integer> entry : entries) {
                    System.out.println(entry.getValue() + "," + entry.getKey());
                }
            }
        }
    
        public static void main(String[] args) {
            ComOrder comOrder = new ComOrder();
            List targetList = comOrder.comp();
            comOrder.print(targetList);
    
        }
    }

[20190124173419381.png]: /images/20220323/13d8daec2a4a4f87aff9819169d15901.png
[20190124173454512.png]: /images/20220323/ead0b85524194802a30bb34a9834e838.png
[20190124173526787.png]: /images/20220323/4706f24f4b4f43c0a0f51a5587eec61a.png