[Java 고급] 1.5장 Test

 

문제

 

학번, 이름, 국어점수, 영어점수, 수학점수, 총점, 등수를 멤버로 갖는 Student클래스를 만든다.
생성자는 학번, 이름, 국어, 영어, 수학 점수만 매개변수로 받아서 처리한다.

이 Student객체들은 List에 저장하여 관리한다.
List에 저장된 데이터들을 학번의 오름차순으로 정렬하여 출력하는 부분과 총점의 역순으로 정렬하는 부분을 프로그램 하시오.
(총점이 같으면 학번의 내림차순으로 정렬되도록 한다.)
(학번 정렬기준은 Student클래스 자체에서 제공하도록 하고, 총점 정렬기준은 외부클래스에서 제공하도록 한다.)

 

 

 

정답

 

package kr.or.ddit.basic.HomeWork;

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

public class HomeWork1_1 {

	public static void main(String[] args) {
		List<Student1> stu = new ArrayList<Student1>();
		
		stu.add(new Student1("1", "홍길동", 98, 70, 100));
		stu.add(new Student1("4", "이순신", 40, 75, 95));
		stu.add(new Student1("3", "성충향", 10, 50, 70));
		stu.add(new Student1("2", "변학도", 70, 90, 80));
		stu.add(new Student1("5", "강감찬", 98, 70, 100));
		
		// sum 합계 넣음
		for (int i = 0; i < stu.size(); i++) {
			Student1 st = stu.get(i);
			int sum = st.getSum();
			stu.get(i).setSum(sum);
		}
		
		// 등수 추가
		for (int i = 0; i < stu.size(); i++) {
			int cnt = 1;
			for (int j = 0; j < stu.size(); j++) {
				if (stu.get(i).getSum() < stu.get(j).getSum()) {
					cnt++;
				}
				stu.get(i).setRank(cnt);
			}
		}
		
		// 정렬전 출력
		System.out.println("\n정렬 전 : ");
		for (Student1 stu1 : stu) {
			System.out.println(stu1);
		}
		
		Collections.sort(stu); // 오름차순 정렬
		
		// 정렬후 출력
		System.out.println("\n정렬 후 : ");
		for (Student1 stu1 : stu) {
			System.out.println(stu1);
		}
		
		System.out.println("===========================================");
		
		Collections.sort(stu, new SortNumDesc1());
		
		// 정렬후 출력
		System.out.println("\n점수별로 내림차순 : ");
		for (Student1 stu1 : stu) {
			System.out.println(stu1);
		}
		
	}
}

class SortNumDesc1 implements Comparator<Student1> {
	@Override
	public int compare(Student1 o1, Student1 o2) {
		if(o1.getSum() < o2.getSum()) {
			return Integer.compare(o1.getSum(), o2.getSum()) * -1;
		} else if (o1.getSum() == o2.getSum()) {
			return o1.getStudentId().compareTo(o2.getStudentId()) * -1;
		} else {
			return -1;
		}
	}
}

class Student1 implements Comparable<Student1>{
	private String studentId;
	private String name;
	private int kor;
	private int eng;
	private int math;
	private int sum;
	private int rank;

	@Override
	public int compareTo(Student1 student) {
		return this.getStudentId().compareTo(student.getStudentId());
	}
	
	public String getStudentId() {
		return studentId;
	}

	public void setStudentId(String studentId) {
		this.studentId = studentId;
	}

	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;
	}

	public int getSum() {
		return getKor() + getEng() + getMath();
	}

	public void setSum(int sum) {
		this.sum = sum;
	}

	public int getRank() {
		return rank;
	}

	public void setRank(int rank) {
		this.rank = rank;
	}

	public Student1(String studentId, String name, int kor, int eng, int math) {
		super();
		this.studentId = studentId;
		this.name = name;
		this.kor = kor;
		this.eng = eng;
		this.math = math;
	}

	@Override
	public String toString() {
		return "Student1 [studentId=" + studentId + ", name=" + name + ", kor=" + kor + ", eng=" + eng + ", math="
				+ math + ", sum=" + sum + ", rank=" + rank + "]";
	}
}

 

결과 화면