java 集合实现comparable接口

偏执的太偏执、 2022-08-17 13:28 229阅读 0赞

import java.util.Scanner;  
import java.util.TreeSet;  
  
/\*  
 \* 编写一个学生成绩管理程序；  
 \* 学生的属性包括学号、姓名、年龄、成绩等；  
 \* 请根据学生学号、姓名、年龄、成绩等进行排序；  
 \*/  
public class Test   
\{  
public static void main(String\[\] args)   
\{  
Scanner scan = new Scanner(System.in);  
int\[\] id = new int\[6\];  
String\[\] name = new String\[6\];  
int\[\] age = new int\[6\];  
double\[\] score = new double\[6\];  
TreeSet<Student> ts = new TreeSet<Student>();  
String str;  
System.out.println("input id,name,age,score:");  
for(int i=0; i<6; i++) //在控制台上输入六个学生的信息；  
\{  
str = scan.next();  
String\[\] str1 = str.split(",");  
id\[i\] = Integer.valueOf(str1\[0\]);  
name\[i\] = str1\[1\];  
age\[i\] = Integer.valueOf(str1\[2\]);  
score\[i\] = Double.valueOf(str1\[3\]);  
ts.add(new Student(id\[i\], name\[i\], age\[i\], score\[i\]));  
\}  
for(Student x:ts)   //使用foreach输出；  
\{  
System.out.println(x);  
\}  
\}

public class Student implements Comparable<Student>  
\{  
int id;  
String name;  
int age;  
double score;  
public Student(int id, String name, int age, double score)  
\{  
this.id = id;  
this.name = name;  
this.age = age;  
this.score = score;  
\}  
  
public int getId()  
\{  
return id;  
\}  
public String getName()  
\{  
return name;  
\}  
public int getAge()  
\{  
return age;  
\}  
public double getScore()  
\{  
return score;  
\}  
  
  
@Override  
public String toString() //重写toString方法，调用时按以下方式输出；  
\{   
return "id=" + id + ", name=" + name + ", age=" + age + ", score=" + score;  
\}  
@Override  
public int compareTo(Student s)    //重写compareTo方法，升序排序，若id相同，则依次往name、age、score推；  
\{  
int num;  
num = id > s.id ? 1 : (id == s.id ? 0 : -1);  
if(num==0)  
\{  
int n = this.name.compareTo(s.name);  
if(n > 0)  
\{  
num = 1;  
\}  
else if(n == 0)  
\{  
num = age > s.age?1:(age==s.age?0:-1);  
if(num == 0)  
\{  
num = score > s.score ? 1 : (score==s.score?0:-1);  
\}  
\}  
else  
\{  
num = -1;  
\}  
\}  
return num;  
\}  
\}