Day 7. 정렬

정렬(Collections sort Comparable Comparator)

package my.examples.javaexam.goodsExample;

public class Student implements Comparable<Student>{
    private String name;

    @Override
    public int compareTo(Student o) {
        return name.compareTo(o.name);
    }

    private int kor;
    private int eng;
    private int math;

    public Student(){

    }

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

    public String getName() {
        return name;
    }

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

    public int getKor() {
        return kor;
    }

    public void setKor(int kor) {
        this.kor = kor;
    }

    public int getEng() {
        return eng;
    }

    public void setEng(int eng) {
        this.eng = eng;
    }

    public int getMath() {
        return math;
    }

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

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", kor=" + kor +
                ", eng=" + eng +
                ", math=" + math +
                '}';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Student student = (Student) o;

        if (kor != student.kor) return false;
        if (eng != student.eng) return false;
        if (math != student.math) return false;
        return name != null ? name.equals(student.name) : student.name == null;
    }

    @Override
    public int hashCode() {
        int result = name != null ? name.hashCode() : 0;
        result = 31 * result + kor;
        result = 31 * result + eng;
        result = 31 * result + math;
        return result;
    }
}

package my.examples.javaexam.goodsExample;

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

public class Score {


    public  static void main(String[] args) {
        List<Student> students = new ArrayList<>();

        Student std1 = new Student("cheongwon", 100, 90, 80);
        Student std2 = new Student("misoo", 80, 100, 90);
        Student std3 = new Student("kyeongsu",90,80,100);

        students.add(std1);
        students.add(std2);
        students.add(std3);

        System.out.println(students);

        Collections.sort(students);

        System.out.println(students);

        Collections.sort(students,new CompartorKor());
        System.out.println(students);

        Collections.sort(students,new CompartorEng());
        System.out.println(students);

        Collections.sort(students,new CompartorMath());
        System.out.println(students);
    }
}
class CompartorKor implements Comparator<Student> {
    @Override
    public int compare(Student o1, Student o2) {
        return o1.getKor() - o2.getKor();
    }
}

class CompartorEng implements Comparator<Student>{
    @Override
    public int compare(Student o1, Student o2) {
        return o1.getEng() - o2.getEng();
    }
}

class CompartorMath implements Comparator<Student>{
    @Override
    public int compare(Student o1, Student o2) {
        return o1.getMath() - o2.getMath();
    }
}