问几个不同的映射可以共享相同的键集吗？

EN

public class StudentExams {
  private Map<Exam, Grade> examGrades = ... //choose whatever you want

  //... constructor and setter methods here if you need them

  public Set<Exam> getExams() {
     return examGrades.keySet();
  }

  /**
    * Returns the Grade for the exam the student took, 
    * or Optional.empty() if the student did not take that exam.
    */ 
  public Optional<Grade> getGrade(Exam exam) {
     return Optional.ofNullable(examGrades.get(exam));
  }
}

Map<String, String> nameMap
Map<String, Long> counterMap
Map<String, Double> scoreMap

class Values {
    String name;
    long counter;
    double score;
}

Map<String, Values> valuesMap;