Java中List根據(jù)map的某個key去重的代碼

2024-07-14 08:43:05

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話不多說，看代碼和效果

   /**   * 根據(jù)map中的某個key 去除List中重復的map   * @author shijing   * @param list   * @param mapKey   * @return   */  public static List<Map<String, Object>> removeRepeatMapByKey(List<Map<String, Object>>       list, String mapKey){    if (CollectionUtils.isNullOrEmpty(list)) return null;     //把list中的數(shù)據(jù)轉(zhuǎn)換成msp,去掉同一id值多余數(shù)據(jù)，保留查找到第一個id值對應的數(shù)據(jù)    List<Map<String, Object>> listMap = new ArrayList<>();    Map<String, Map> msp = new HashMap<>();    for(int i = list.size()-1 ; i>=0; i--){      Map map = list.get(i);      String id = (String)map.get(mapKey);      map.remove(mapKey);      msp.put(id, map);    }    //把msp再轉(zhuǎn)換成list,就會得到根據(jù)某一字段去掉重復的數(shù)據(jù)的List<Map>    Set<String> mspKey = msp.keySet();    for(String key: mspKey){      Map newMap = msp.get(key);      newMap.put(mapKey, key);      listMap.add(newMap);    }    return listMap;  }

測試：

public static void main(String[] args) {    Map<String, Map> msp = new HashMap<String, Map>();    List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();    List<Map<String, Object>> listMap = new ArrayList<Map<String,Object>>();    Map<String, Object> map1 = new HashMap<String, Object>();    map1.put("id", "1123");    map1.put("name", "張三");    Map<String, Object> map2 = new HashMap<String, Object>();    map2.put("id", "2");    map2.put("name", "李四");    Map<String, Object> map3 = new HashMap<String, Object>();    map3.put("id", "1123");    map3.put("name", "王五");    Map<String, Object> map4 = new HashMap<String, Object>();    map4.put("id", "3");    map4.put("name", "趙六");    list.add(map1);    list.add(map2);    list.add(map3);    list.add(map4);    System.out.println("初始數(shù)據(jù)：" + list.toString());    System.out.println("去重之后：" + removeRepeatMapByKey(list,"id"));  }

結(jié)果：