for (Entity e : rsList) { List<String> singleRecord = new ArrayList<>(); nameList.forEach(n -> singleRecord.add(e.get(n) == null ? "" : e.get(n).toString())); if (e.getMetadata().containsKey(ChargeConst.RATE_RULE_DETAIL)) { Set<Map<String, Object>> ruleDtls = (Set<Map<String, Object>>) e.getMetadata().get(ChargeConst.RATE_RULE_DETAIL); Map<Object, Object> mergedMap = ruleDtls.stream() .flatMap(map -> map.entrySet().stream().map(entry -> new AbstractMap.SimpleEntry<>(entry.getKey(), entry.getValue() == null ? "" : entry.getValue()))) .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (oldValue, newValue) -> newValue)); final List<String> finalSingleRecord = singleRecord; valueList.add(IntStream.range(0, finalSingleRecord.size()).mapToObj( i -> finalSingleRecord.get(i).equals("") && mergedMap.get(nameList.get(i)) != null ? mergedMap.get(nameList.get(i)).toString() : finalSingleRecord.get(i)) .collect(Collectors.toList())); continue; } valueList.add(singleRecord); }降低代码复杂度

可以将代码分解为多个方法来降低复杂度，例如：

1. 提取一个方法来处理每个实体记录，将其转换为一个 String 类型的 List。

private List<String> processEntity(Entity e, List<String> nameList) {
    List<String> singleRecord = new ArrayList<>();
    nameList.forEach(n -> singleRecord.add(e.get(n) == null ? "" : e.get(n).toString()));
    if (e.getMetadata().containsKey(ChargeConst.RATE_RULE_DETAIL)) {
        Set<Map<String, Object>> ruleDtls = (Set<Map<String, Object>>) e.getMetadata().get(ChargeConst.RATE_RULE_DETAIL);
        Map<Object, Object> mergedMap = mergeRuleDetails(ruleDtls);
        final List<String> finalSingleRecord = singleRecord;
        return IntStream.range(0, finalSingleRecord.size())
                .mapToObj(i -> finalSingleRecord.get(i).equals("") && mergedMap.get(nameList.get(i)) != null ? mergedMap.get(nameList.get(i)).toString() : finalSingleRecord.get(i))
                .collect(Collectors.toList());
    }
    return singleRecord;
}

2. 提取一个方法来合并所有规则细节的 Map。

private Map<Object, Object> mergeRuleDetails(Set<Map<String, Object>> ruleDtls) {
    return ruleDtls.stream()
            .flatMap(map -> map.entrySet().stream()
                    .map(entry -> new AbstractMap.SimpleEntry<>(entry.getKey(), entry.getValue() == null ? "" : entry.getValue())))
            .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (oldValue, newValue) -> newValue));
}

3. 将原来的主方法进行简化，使用上面的两个方法来处理每个实体记录，并将结果添加到 valueList 中。

for (Entity e : rsList) {
    List<String> singleRecord = processEntity(e, nameList);
    valueList.add(singleRecord);
}