Question

转换这个嵌套的迭代是我的想法，有人可以将此转换为并行流吗？我希望能够检查符合我的每个帐户小组成员标准的作业。我刚刚切换到java 8，并且正在努力围绕利用并行流来预先形成这种聚合的最佳方式。

for(Iterator<BasicDBObject> iterator = members.iterator(); iterator.hasNext();) {
    BasicDBObject member = iterator.next();

    //if the member doesn't have a valid assignment remove them.
    boolean memberContainsValidAssignment = false;

    BasicDBObject role = member.get("accountTeamRole") == null ? null : (BasicDBObject) member.get("accountTeamRole");
    if (accTeamRoleCodes != null && !accTeamRoleCodes.contains(role.get("code"))) {
        iterator.remove();
        continue;
    }

    List<BasicDBObject> assignments = member.get("assignments") == null ? new ArrayList<>() : (List) member.get("assignments");
    for (Iterator<BasicDBObject> assignIterator = assignments.iterator(); assignIterator.hasNext(); ) {
        BasicDBObject assignment = assignIterator.next();

        Date endDate = (Date) assignment.get("assignmentValidToDate");
        Date startDate = (Date) assignment.get("assignmentValidFromDate");

        if(startDate == null){//this is junk, should have never been allowed.
            LOGGER.warn("There's no start date for this assignment. {}", assignment.toString());
            assignIterator.remove();
            continue;
        }
        //1. open ended assignment, it lives on forever. 2.falls in between active date.
        else if(endDate == null ||(activeDate.after(startDate) && activeDate.before(endDate))){
            LOGGER.debug("adding an assignment. {}", assignment.toString());
            memberContainsValidAssignment = true;
            convertDatesToString(assignment);
            continue;
        }

    }
    if(!memberContainsValidAssignment){
        iterator.remove();
    }
}

Answer 1

以下是将代码转换为使用流的镜头。请检查过滤条件的详细信息。

 List<BasicDBObject> invalidAssignments = members.stream()
        .filter(member -> accTeamRoleCodes == null || 
                          member.get("accountTeamRole") == null || 
                          accTeamRoleCodes.contains(member.get("accountTeamRole").get("code"))
               )
        .flatMap(member -> member.get("assignments").stream())
        .filter(assignment -> (Date) assignment.get("assignmentValidFromDate") != null && 
                              ((Date) assignment.get("assignmentValidToDate") != null || 
                              (activeDate.after((Date)assignment.get("assignmentValidFromDate")) && 
                               activeDate.before((Date)assignment.get("assignmentValidToDate"))))
               )
        .collect(Collectors.toList());

要使事情平行，只需使用members.parallelStream代替members.stream。

将迭代器代码转换为Stream

1 个答案: