1Z0-809 Question #254: Real Exam Question with Answer & Explanation

Given:

class Student {
 String course, name, city;
 public Student(String name, String course, String city) {
 this.course = course; this.name = name; this.city = city;
 }
 public String toString() {
 return course + ":" + name + ";" + city;
 }
 public String getCourse() { return course; }
 public String getName() { return name; }
 public String getCity() { return city; }
}

And the code fragment:

List<Student> stds = Arrays.asList(
 new Student ("Jessy", "Java ME", "Chicago"),
 new Student ("Helen", "Java EE", "Houston"),
 new Student ("Mark", "Java ME", "Chicago"));
stds.stream()
 .collect(Collectors.groupingBy(Student::getCourse))
 .forEach((src, res) -> System.out.println(src));

What is the result?