JavaSE-15.2.4【案例-成绩排序（比较器排序Comparator实现、自然排序Comparable实现）】

package day6.lesson2.anli1;

import java.util.Comparator;
import java.util.TreeSet;

/*
2.4 案例-成绩排序

    用TreeSet集合存储多个学生信息(姓名，语文成绩，数学成绩)，并遍历该集合
    要求：按照总分从高到低出现

    通过 比较器排序Comparator 实现
    通过 自然排序Comparable 实现
 */
//通过 比较器排序Comparator 实现
public class TreeSetDemo4 {
    public static void main(String[] args) {
        TreeSet<Student> ts = new TreeSet<>(new Comparator<Student>() {
            @Override
            public int compare(Student s1, Student s2) {
//                return 0;

                /*int score_s1 = s1.getChinese() + s1.getMath();
                int score_s2 = s2.getChinese() + s2.getMath();
                int num = score_s2 - score_s1;
                return num;*/

                int num = s2.getSum() - s1.getSum();
                int num2 = ( num==0 ? s1.getChinese()-s2.getChinese() : num );
                int num3 = ( num2==0 ? s1.getName().compareTo(s2.getName()) : num2 );
                return num3;
            }
        });

        Student s1 = new Student("tom", 100, 80);
        Student s2 = new Student("amy", 85, 90);
        Student s3 = new Student("sam", 79, 100);
        Student s4 = new Student("jji", 90, 95);
        Student s5 = new Student("bba", 95, 90);
        Student s6 = new Student("cca", 95, 90);

        ts.add(s1);
        ts.add(s2);
        ts.add(s3);
        ts.add(s4);
        ts.add(s5);
        ts.add(s6);

        for (Student s: ts){
//            System.out.println(s.getName() + "," + (s.getChinese()+s.getMath()) );
            System.out.println(s.getName() + "," + s.getSum());
        }
        /*
        jji,185
        bba,185
        cca,185
        tom,180
        sam,179
        amy,175
         */
    }
}

package day6.lesson2.anli1;

public class Student {

    private String name;
    private int chinese;
    private int math;

    public Student() {
    }

    public Student(String name, int chinese, int math) {
        this.name = name;
        this.chinese = chinese;
        this.math = math;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setChinese(int chinese) {
        this.chinese = chinese;
    }

    public void setMath(int math) {
        this.math = math;
    }

    public String getName() {
        return name;
    }

    public int getChinese() {
        return chinese;
    }

    public int getMath() {
        return math;
    }

    public int getSum(){
        return this.chinese + this.math;
    }
}

package day6.lesson2.anli1_1;

import java.util.TreeSet;

//通过 自然排序Comparable 实现
public class TreeSetDemo5 {
    public static void main(String[] args) {
        TreeSet<Student> ts = new TreeSet<>();

        Student s1 = new Student("tom", 100, 80);
        Student s2 = new Student("amy", 85, 90);
        Student s3 = new Student("sam", 79, 100);
        Student s4 = new Student("jji", 90, 95);
        Student s5 = new Student("bba", 95, 90);
        Student s6 = new Student("cca", 95, 90);

        ts.add(s1);
        ts.add(s2);
        ts.add(s3);
        ts.add(s4);
        ts.add(s5);
        ts.add(s6);

        for (Student s: ts){
            System.out.println(s.getName() + "," + s.getSum());
        }
        /*
        jji,185
        bba,185
        cca,185
        tom,180
        sam,179
        amy,175
         */
    }
}

package day6.lesson2.anli1_1;

public class Student implements Comparable<Student>{

    private String name;
    private int chinese;
    private int math;

    public Student() {
    }

    public Student(String name, int chinese, int math) {
        this.name = name;
        this.chinese = chinese;
        this.math = math;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setChinese(int chinese) {
        this.chinese = chinese;
    }

    public void setMath(int math) {
        this.math = math;
    }

    public String getName() {
        return name;
    }

    public int getChinese() {
        return chinese;
    }

    public int getMath() {
        return math;
    }

    public int getSum(){
        return this.chinese + this.math;
    }

    @Override
    public int compareTo(Student s) {
//        return 0;

        int num = s.getSum() - this.getSum();
        int num2 = ( num==0 ? this.getChinese()-s.getChinese() : num);
        int num3 = ( num2==0 ? this.getName().compareTo(s.getName()) : num2 );
        return num3;
    }
}