java循环情况下的递归缺失

Question

我的目标是将所有团队成员与团队领导人联系起来，但要分层次进行。比尔是一位顶尖的队长，约翰和艾丽斯比他低一级，玛丽比约翰和爱丽丝低一级，等等。

Team leader   Team members
=========      ==========
Bob           ""
Marry        Bob
John         Marry
Alice        Marry
Bill         John,Alice

所以我用

final static SetMultimap<String, String> teamMap = HashMultimap
    .create();

我想给每一位队长一个完整的团队成员名单。

eg : For Alice as a Team Leader, her full team members list is Marry, Bob. 
     For Bill as a Team Leader, his full team members list is John, Alice, Marry, Bob

由于递归似乎解决了我的问题，所以我使用以下方法

   public static List<String> getTeamMembers(String teamLeader) {

    List<String> teamMembers = teamMembersMap.get(teamLeader);
    fullTeamMembers.addAll(teamMembers);

    for (String teamMember : teamMembers) {
        if (teamMember.equalsIgnoreCase("")) {
**// if teamMember is John go to Marry then Bob and return recursively 
// without treating Alice loop!**
        return fullTeamMembers;
        } else {
        return getTeamMembers(teamMember);
        }
    }
**// compiler error otherwise force to return something here
// maybe in case teamMembers is empty****
    return null;

    }

还有我的电话

for (String teamLeader : teamMembersMap.keySet()) {
    System.out.println("********************************");
    System.out.println("**************teamLeader :" + teamLeader);
    fullTeamMembers.clear();
    List<String> fullTeamMembers = getTeamMembers(teamLeader);
    teamMembersMap.putAll(teamLeader, fullTeamMembers);

}

但是，我对代码中注释中的两点进行了讨论:循环问题和返回编译器错误。欢迎任何帮助以更好的方式解决这个问题。

Answer 1

当然，它告诉您要在那里放置一个return语句。您的teamMembers可以是空的，甚至是空的。除了一些缺失的空/空检查之外，您的代码没有任何问题。

如果你真的想要一个改进和无效的安全，下面是我的建议：

public static List<String> getTeamMembers(final String teamLeader) 
{
     final List<String> result = new ArrayList<>(); // fullTeamMembers
     final List<String> teamMembers = teamMembersMap.get(teamLeader); // Can be NULL or empty

     if (teamMembers == null || teamMembers.isEmpty())
          return result; // Return empty array

     // Else, carry on
     result.addAll(teamMembers);

     for (String teamMember : result) 
          if ( !teamMember.equalsIgnoreCase("") ) 
               return getTeamMembers(teamMember); // Go recursively if not ""

     // Return result from map
     return result;
}