flatMap 算子

// F_KJQJ 会计期间

private static List<String> kjqjList = Arrays.asList("202208", "202209");

// F_KMBH 科目编号
private static List<String> kmbhList = Arrays.asList("1001", "1002");

// F_CODE 责任中心
private static List<String> codeList = Arrays.asList("201222221002", "201222221003", "201222221004");

 

需要计算上面三个维度的笛卡尔积组合，调用远程fmis接口获取数据。

public final static String delimiter = " ";

public static List<String> descartes(List<String>... lists) {

    List<String> result = new ArrayList<>();
    for (List<String> list : lists) {
        if (CollectionUtils.isEmpty(result)) {
            result = list;
        } else {
            result = result.stream().flatMap(itemParent -> list.stream().map(itemChild -> itemParent + ToolsUtil.delimiter + itemChild))
                    .collect(Collectors.toList());
        }
    }
    return result;

}

List<String> descartesList = ToolsUtil.descartes(kjqjList, kmbhList, codeList);

for (String descartes : descartesList) {
　　　　//rpc 
}