下面代码输出的结果为:
import java.util.ArrayList; import java.util.Collections; import java.util.List; public class Test{ public static void main(String[] args) { List<Student> students = new ArrayList<Student>(); students.add(new Student(10)); students.add(new Student(18)); students.add(new Student(15)); Collections.sort(students); System.out.print(students.get(1).age); } } class Student implements Comparable<Student> { Integer age; public Student(Integer age) { this.age = age; } public int compareTo(Student s) { return s.age.compareTo(this.age); } }