将List中属性相同的值求和，返回没有重名的List

    // 将List中属性相同的值求和，返回没有重名的List
    Map<Integer, VipLevelResponse> map = new HashMap<>();
    for (VipLevelResponse response : responses) {
      int level = response.getLevel();
      // value)该方法判断Map集合中是否包含指定的键值，如果包含返回true，不包含返回false
      if (map.containsKey(level)) {
        VipLevelResponse levelResponse = new VipLevelResponse();
        levelResponse.setLevel(level);
        // 合并相同key的value
        levelResponse.setCount(map.get(level).getCount() + response.getCount());
        // HashMap不允许key重复，当有key重复时，前面key对应的value值会被覆盖
        map.put(level, levelResponse);
      } else {
        map.put(level, response);
      }
    }
    log.info(">>>map:[{}]", map);
    List<VipLevelResponse> vipLevels = new ArrayList<>();
    Iterator iter = map.entrySet().iterator();
    while (iter.hasNext()) {
      Map.Entry entry = (Map.Entry) iter.next();
      VipLevelResponse response = (VipLevelResponse) entry.getValue();
      vipLevels.add(response);
    }

  /** 会员等级构成. */
  private String memberLevel(List<VipLevelResponse> vipLevelResponses) {
    StringBuilder vipLevel = new StringBuilder();
    // 遍历
    for (VipLevelResponse vipLevelResponse : vipLevelResponses) {
      // vip等级
      int level = vipLevelResponse.getLevel();
      // 数量
      long count = vipLevelResponse.getCount();
      vipLevel.append(";").append(level).append(":").append(count);
    }
    // 如果vipLevel不为空，则去掉 StringBuilder 的第一个字符
    if (!"".contentEquals(vipLevel)) {
      vipLevel.deleteCharAt(0);
    }
    return vipLevel + "";
  }