Making Java Objects Comparable

package example.comparator;

import java.util.Arrays;

import java.util.Set;

import java.util.TreeSet;

public class Person implements Comparable {

    String firstName, lastName;

    public Person(String f, String l) {

	this.firstName = f;

	this.lastName = l;

    }

    public String getFirstName() {

	return firstName;

    }

    public String getLastName() {

	return lastName;

    }

    public String toString() {

	return "[dept=" + firstName + ",name=" + lastName + "]";

    }

    public int compareTo(Object obj) {

	Person emp = (Person) obj;

	int deptComp = firstName.compareTo(emp.getFirstName());

	return ((deptComp == 0) ? lastName.compareTo(emp.getLastName()) : deptComp);

    }

    public boolean equals(Object obj) {

	if (!(obj instanceof Person)) {

	    return false;

	}

	Person emp = (Person) obj;

	return firstName.equals(emp.getFirstName()) && lastName.equals(emp.getLastName());

    }

    public static void main(String args[]) {

	Person emps[] =

		{ new Person("Debbie", "Degree"), new Person("Geri", "Grade"), new Person("Ester", "Extent"),

			new Person("Mary", "Measure"), new Person("Anastasia", "Amount") };

	Set set = new TreeSet(Arrays.asList(emps));

	System.out.println(set);

    }

}