RajR.java

RajR.java

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

public class RajR {

    public static class Person {
        private final String firstname;
        private final String surname;
        private final int age;
        private final String sex;
        public Person(String firstname, String surname, int age, String sex) {
            this.firstname = firstname;
            this.surname = surname;
            this.age = age;
            this.sex = sex;
        }
        public int getAge() {
            return this.age;
        }
        public String toString() {
            return String.format("Person firstname=%s, surname=%s, age=%s, sex=%s.", this.firstname, this.surname, this.age, this.sex);
        }
    }

    public static class AgeComparator implements Comparator<Person> {
        @Override
        public int compare(Person p1, Person p2) {
            return Integer.compare(p1.getAge(), p2.getAge());
        }
    }

    public static void main(final String[] args) {
        final List<Person> peopleList = new ArrayList<Person>();
        peopleList.add(new Person ( "Raj","R",22,"M"));
        peopleList.add(new Person ( "Leo","Messi",18,"M"));
        peopleList.add(new Person ( "Cr7","Ronaldo",40,"M"));
        peopleList.add(new Person ( "A","Jr",60,"F"));
        peopleList.add(new Person ( "B","Jr",70,"F"));
        peopleList.add(new Person ( "C","Jr",80,"F"));
        peopleList.add(new Person ( "D","Jr",90,"F"));

        System.out.println("List Before Sort");
        for (final Person p : peopleList) {
            System.out.println(p);
        }

        Collections.sort(peopleList, new AgeComparator());

        System.out.println("List After Sort");
        for (final Person p : peopleList) {
            System.out.println(p);
        }

        System.out.println("Youngest = " + peopleList.get(0));
        System.out.println("Oldest = " + peopleList.get(peopleList.size() - 1));
    }

}