package linkedList;

import java.util.*;

public class JavaComparable {

    public static void main(String[] args){
        Student st1=new Student();
        st1.setId(2);
        Student st2=new Student();
        st2.setId(1);
        LinkedList ll=new LinkedList();
        ll.add(st1);
        ll.add(st2);
        System.out.print("before sort: ");
        for(int i=0;i<ll.size();i++){
            System.out.print(((Student)ll.get(i)).getId()+" ");
        }
        System.out.println("");
        Collections.sort(ll);
        System.out.print("after sort: ");
        for(int i=0;i<ll.size();i++){
            System.out.print(((Student)ll.get(i)).getId()+" ");
        }
    }

}

class Student implements Comparable{
    int id;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    @Override
    public int compareTo(Object o) {

        int id;
        if(o instanceof Student){
            id=((Student)o).getId();
        }else{
            throw new RuntimeException("wrong type");
        }

        if(this.id>id){
            return 1;
        }else if(this.id<id){
            return -1;
        }else{
            return 0;
        }
    }

}