Here is an example that stores the employee information into the hashmap and display the data according to the date of birth.

import java.util.*;
import java.text.*;

class Employee{
String name;
    String address;
    Date d;
    Employee(String name,String address,Date d){
        this.name=name;
        this.address=address;
        this.d=d;
    }
    public String getName(){
        return name;
    }
    public String getAddress(){
        return address;
    }
    public Date getDate(){
        return d;
    }

}
class BirthDateComparator implements Comparator<Employee> {
    public int compare(Employee p, Employee q) {
        if (p.getDate().before(q.getDate())) {
            return +1;
        } else if (p.getDate().after(q.getDate())) {
            return -1;
        } else {
            return 0;
        }        
    }
}
public class EmployeeDateInAscendingOrder{
public static void main(String[] args) throws Exception{
List<Employee> list = new ArrayList<Employee>();
SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
list.add(new Employee("Victor","Delhi",28000));
list.add(new Employee("Jennie","Mumbai",22000));
list.add(new Employee("John","Chennai",40000));
list.add(new Employee("Daniel","Kolkata",25000));
list.add(new Employee("Angelina","Pune",20000));

System.out.println("Youngest to Oldest...... ");
               Collections.sort(list,new BirthDateComparator());
                for(Employee data: list){
                System.out.println(data.getName()+"\t"+data.getAddress()+"\t"+sdf.format(data.getDate()));
                }               
           }
}