Java流，备份流状态

Question

在使用 java 流 API 迭代时“备份”集合状态的最简洁方法是什么？

例如，我如何“实现”.backup(allRules)？

ArrayList<String> allRules = new ArrayList<>(); 
Set<String> businessRules = result.getRules().stream()
        .map(name -> replace(name, RULES_PACKAGE_NAME, EMPTY))
        .backup(allRules)
        .filter(name -> !NON_BUSINESS_RULES.contains(name))
        .collect(toSet());

Answer 1

只需两步即可完成？

   List<String> allRules = result.getRules().stream()
        .map(name -> replace(name, RULES_PACKAGE_NAME, EMPTY))
        .collect(Collectors.toList());

    Set<String> businessRules = allRules.stream()
        .filter(name -> !NON_BUSINESS_RULES.contains(name))
        .collect(toSet());