使用Guava的ComparisonChain实现自定义的排序

package comparable;

import com.google.common.collect.ComparisonChain;
import lombok.Data;

import java.util.*;

/**
 * @author xfyou
 * @date 2018/9/30
 */
@Data
public class Course implements Comparable<Course> {

    /**
     * 学号
     */
    private String studentNumber;

    /**
     * 姓名
     */
    private String studentName;

    /**
     * 分数
     */
    private int score;

    @Override
    public int compareTo(Course course) {
        return ComparisonChain.start()
                .compare(course.score, this.score)
                .compare(this.studentNumber, course.studentNumber)
                .result();
    }

    public static void main(String[] args) {
        TreeSet<Course> coursesSet = new TreeSet<>();

        Course course3 = new Course();
        course3.setScore(95);
        course3.setStudentName("Smith");
        course3.setStudentNumber("1003");
        coursesSet.add(course3);

        Course course1 = new Course();
        course1.setScore(90);
        course1.setStudentName("Frank");
        course1.setStudentNumber("1110");
        coursesSet.add(course1);

        Course course2 = new Course();
        course2.setScore(90);
        course2.setStudentName("Tom");
        course2.setStudentNumber("0002");
        coursesSet.add(course2);

        // 编译时使用iterator实现
        for (Course course : coursesSet) {
            System.out.println(course);
        }
    }

}

按照分数由大到小，分数相同的情况下按照学号由小到大来排序。运行结果如下：

Course(studentNumber=1003, studentName=Smith, score=95)
Course(studentNumber=0002, studentName=Tom, score=90)
Course(studentNumber=1110, studentName=Frank, score=90)