Question

使用Java 1.5如何将以下列表结构转换为嵌套映射：

List<CsSectionDetail> list至Map<Integer,Map<Integer, List<CsSectionDetail>>> map = new TreeMap<Integer, Map<Integer,List<CsSectionDetail>>>();

上面的列表包含两个键 mainTaskId 和 subTaskId ，它们应该使用 first Integer mainTaskId 和转换为上面的地图结构second Integer subTaskId 。

我已经有了一个将List<CsSectionDetail>列表转换为map的函数，其结构为Map<Integer, List<CsSectionDetail>> map = new HashMap<Integer, List<CsSectionDetail>>(); 以下是代码

public Map<Integer, List<CsSectionDetail>> getCsSectionDetail4Display(List<CsSectionDetail> list, boolean groupByMainTaskOnly) {
        Map<Integer, List<CsSectionDetail>> map = new HashMap<Integer, List<CsSectionDetail>>();

        Iterator<CsSectionDetail> it = list.iterator();
    while(it.hasNext()){
            CsSectionDetail csDetail = (CsSectionDetail) it.next();
            add2Map(csDetail, map, groupByMainTaskOnly);
    }
    return map;
    }

private void add2Map(CsSectionDetail csDetail, Map<Integer, List<CsSectionDetail>> map, boolean groupByMainTaskOnly) {
       List<CsSectionDetail> list;
        Integer key; 

        if (groupByMainTaskOnly) {
            key = csDetail.getProjectTaskId().getId();
        } else {
            if (csDetail.getProjectSubTaskId() == 0) {
                key = csDetail.getProjectTaskId().getId();
            } else {
                key = new Integer(csDetail.getProjectSubTaskId());
            }
        }
        list = (List<CsSectionDetail>) map.get(key);
        if (list == null) {
            list = new ArrayList<CsSectionDetail>();
        }

如何修改上面的代码来获取嵌套的地图结构？

由于

Answer 1

为了清晰起见，用两种方法剪切代码，每种方法都在不同的级别填充地图：

private void add2TaskMap(CsSectionDetail csDetail, Map<Integer, Map<Integer,CsSectionDetail>> map) {
    Map<Integer,CsSectionDetail> submap;
     Integer key = csDetail.getProjectTaskId().getId();

     submap =map.get(key);
     if (submap == null) {
         submap = new HashMap<Integer,CsSectionDetail>();
         map.put(key, submap);
     }
     add2SubTaskMap(csDetail, submap);
}

private void add2SubTaskMap(CsSectionDetail csDetail, Map<Integer,CsSectionDetail> map) {
     Integer key;
     if (csDetail.getProjectSubTaskId() == 0) {
         key = csDetail.getProjectTaskId().getId();
     } else {
         key = new Integer(csDetail.getProjectSubTaskId());
     }

     map.put(key, csDetail);
}

将列表转换为地图

1 个答案: