//学生信息 -- 拓展信息

Map<Student, String> map = new HashMap<Student, String>(16);

map.put(new Student("zhangsan", 22), "优秀学生");

map.put(new Student("lisi", 22), "三好学生");

for (Student student : map.keySet()) {

     System.out.println("key = " + student);

     System.out.println("key.name = " + student.getName());

     System.out.println("key.age = " + student.getAge());

     System.out.println("value = " + map.get(student));

}