import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

class SortByMark implements Comparator<Student> {
  @Override
  public int compare(Student studentOne, Student studentTwo) {
    return studentOne.getMark().compareTo(studentTwo.getMark());
  }
}

class Student {
  final Double mark;
  private final String name;

  public Student(String name, Double mark) {
    this.name = name;
    this.mark = mark;
  }

  public Double getMark() {
    return mark;
  }

  public String getName() {
    return name;
  }

  @Override
  public String toString() {
    return name + ": " + mark;
  }
}
public class Main {
  public static void main(String args[]) {
    List<Student> students = new ArrayList<Student>();
    SortByMark sortByMark = new SortByMark();

    students.add(new Student("A", new Double(34.34)));
    students.add(new Student("C", new Double(123.22)));
    students.add(new Student("B", new Double(13.00)));
    students.add(new Student("Z", new Double(99.22)));
    students.add(new Student("X", new Double(-19.08)));

    Collections.sort(students, sortByMark);

    for (Student student : students) {
      System.out.println(student);
    }
  }
}

運(yùn)行結(jié)果如下: