How sort list of object with multiple data sort in java

package example;

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

public class Demo {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Demo demo = new Demo();
        List<Student> list = new ArrayList<Student>(); // your Car list
        Student st = demo.new Student();
        st.setName("sekhar");
        st.setCity("bbsr");
        st.setRoll(23);
        list.add(st);
        st = demo.new Student();
        st.setName("himanshu");
        st.setCity("agra");
        st.setRoll(23);
        list.add(st);
        st = demo.new Student();
        st.setName("nitin");
        st.setCity("delhi");
        st.setRoll(23);
        list.add(st);
        st = demo.new Student();
        st.setName("nitin");
        st.setCity("delhi");
        st.setRoll(22);
        list.add(st);
        st = demo.new Student();
        st.setName("nitin");
        st.setCity("bbsr");
        st.setRoll(23);
        list.add(st);
        st = demo.new Student();
        st.setName("arun");
        st.setCity("patna");
        st.setRoll(23);
        list.add(st);
        st = demo.new Student();
        st.setName("arun");
        st.setCity("kendrapara");
        st.setRoll(23);
        list.add(st);
        System.out.println("before sort");
        System.out.println("Name:" + "-------------------" + "City...........roll");
        for (Student st1 : list) {
            System.out.println(st1.getName() + " --------------" + st1.getCity() + "------------" + st1.getRoll());
        }

        Collections.sort(list, demo.new CarHorsePowerComparator());
        System.out.println("after sort");
        System.out.println("Name:" + "-------------------" + "City...............roll");
        for (Student st1 : list) {
            System.out.println(st1.getName() + " --------------" + st1.getCity() + "------------" + st1.getRoll());
        }
    }

    public class Student {

        String name;
        String city;
        int roll;

        public int getRoll() {
            return roll;
        }

        public void setRoll(int roll) {
            this.roll = roll;
        }

        public String getCity() {
            return city;
        }

        public void setCity(String city) {
            this.city = city;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    }

    class CarHorsePowerComparator implements Comparator<Student> {
        private final Collator collator = Collator.getInstance(); //Default local is taken.

          public int compare(Student left, Student right) {

            int result = collator.compare(left.getName(),right.getName());

            if(result == 0) {
                result = collator.compare(right.getCity(),left.getCity());
            }

            if(result == 0) {
                result = Integer.compare(left.getRoll(), right.getRoll()); //JDK 7
               //result = Double.compare(left.getRoll(), right.getRoll());
            }

            return result;
        }
    }
}

OutPut:

before sort
Name:-------------------City...........roll
sekhar --------------bbsr------------23
himanshu --------------agra------------23
nitin --------------delhi------------23
nitin --------------delhi------------22
nitin --------------bbsr------------23
arun --------------patna------------23
arun --------------kendrapara------------23
after sort
Name:-------------------City...............roll
arun --------------patna------------23
arun --------------kendrapara------------23
himanshu --------------agra------------23
nitin --------------delhi------------22
nitin --------------delhi------------23
nitin --------------bbsr------------23
sekhar --------------bbsr------------23