package Practice;

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

public class Sort {
    public static void main(String args[]){
        Student a = new Student();
        a.setClasses(1);
        a.setId(1);
        a.setName("liufei");
        a.setScore(100);
        Student b = new Student();
        b.setClasses(2);
        b.setId(1);
        b.setName("liu");
        b.setScore(100);
        List<Student> list = new ArrayList<Student>();
        list.add(a); list.add(b);
        Collections.sort(list);
        for(Student na:list){
            System.out.println("na.getName()");
        }
    }   
   
}
class Student implements Comparable<Student>{
    private String name;
    private int id;
    private int classes;
    private int score;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public int getClasses() {
        return classes;
    }
    public void setClasses(int classes) {
        this.classes = classes;
    }
    public int getScore() {
        return score;
    }
    public void setScore(int score) {
        this.score = score;
    }
    @Override
    public int compareTo(Student o) {
        // TODO Auto-generated method stub
        return this.getScore().compareTo(o.getScore());//这句话在myeclipse下面显示错误
    }
   
   
}

compareTo这个方法得是实现了java.接口的类的对象才能调，int类型不具备条件。

返回值是int类型