Java tutorial
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); } }