248 成绩排序
【需求】
用存储多个学生的信息（语文、数学分数）并遍历
要求，按分数从高到低排序输出
这里使用比较器排序
自己用自然排序做练习
【代码思路】
- 定义学生类
- 创建TreeSet集合对象，通过比较器排序进行排序
- 创建学生对象
- 添加学生对象到集合
- 遍历集合，按分数从高到低输出
【代码过程事件】
如果不做以下处理
@Override
public int compare(Student248 s1, Student248 s2) {
// int num1 = (s2.getChineseScore() + s2.getMathScore())-(s1.getChineseScore() - s1.getMathScore());
int num2 = s2.getScoreSum() - s1.getScoreSum();//主要条件
int num3 = num2==0?s1.getChineseScore() - s1.getChineseScore() : num2;//次要条件
int num4 = num3==0?s1.getName().compareTo(s2.getName()) : num3;
return num4;
}
系统将无法添加总分相同的学生，即使姓名不同、各科分数不同
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1 package e248;
2
3 import java.util.Comparator;
4 import java.util.TreeSet;
5
6 public class TreeSetDemo248 {
7 public static void main(String[] args) {
8 TreeSet<Student248> ts248 = new TreeSet<Student248>(new Comparator<Student248>() {
9 @Override
10 public int compare(Student248 s1, Student248 s2) {
11 // int num1 = (s2.getChineseScore() + s2.getMathScore())-(s1.getChineseScore() - s1.getMathScore());
12 int num2 = s2.getScoreSum() - s1.getScoreSum();
13 int num3 = num2==0?s1.getChineseScore() - s1.getChineseScore() : num2;
14 int num4 = num3==0?s1.getName().compareTo(s2.getName()) : num3;
15 return num4;
16 }
17 });//如果学科多，用num2更好
18 //num2，在Student248里定义个方法，计算总成绩，调用时直接调用总成绩
19 Student248 zz1 = new Student248("AVA",7,7);
20 Student248 zz2 = new Student248("MOLE",2,2);
21 Student248 zz3 = new Student248("RAT",8,8);
22 Student248 zz4 = new Student248("TOAD",1,1);
23 Student248 zz5 = new Student248("BADGER",8,8);
24
25 ts248.add(zz1);
26 ts248.add(zz2);
27 ts248.add(zz3);
28 ts248.add(zz4);
29 ts248.add(zz5);
30
31 System.out.println("---29---");
32 for (Student248 s248 : ts248 ) {
33 System.out.print(s248.getName()+","+s248.getMathScore()+","+s248.getChineseScore());
34 System.out.println(", and in total:"+s248.getScoreSum());
35 }
36
37 }
38 }
--------------------------------------------------------------
1 package e248;
2
3 public class Student248 {
4 private String name;
5 private int ChineseScore;
6 private int MathScore;
7
8 public Student248() {
9 }
10
11 public Student248(String name, int chineseScore, int mathScore) {
12 this.name = name;
13 ChineseScore = chineseScore;
14 MathScore = mathScore;
15 }
16
17 public String getName() {
18 return name;
19 }
20
21 public void setName(String name) {
22 this.name = name;
23 }
24
25 public int getChineseScore() {
26 return ChineseScore;
27 }
28
29 public void setChineseScore(int chineseScore) {
30 ChineseScore = chineseScore;
31 }
32
33 public int getMathScore() {
34 return MathScore;
35 }
36
37 public void setMathScore(int mathScore) {
38 MathScore = mathScore;
39 }
40 public int getScoreSum(){
41 return this.getChineseScore() + this.getMathScore();
42 }
43 }