Creating a Comparable object : Comparator « Collections Data Structure « Java

Creating a Comparable object

Creating a Comparable object
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));

Related examples in the same category

1. Writing Your own Comparator Writing Your own Comparator
2.A Class Implementing Comparable
3.Comparator for comparing strings ignoring first character
4.List and Comparators
5.Sort backwards
6.Company and Employee
7.Search with a Comparator
8.Keep upper and lowercase letters togetherKeep upper and lowercase letters together
9.Uses anonymous inner classesUses anonymous inner classes
10.Building the anonymous inner class in-placeBuilding the anonymous inner class in-place
11.Sort an array of strings in reverse order.
12.Sort an array of strings, ignore case difference.
13.Comparator uses a Collator to determine the proper, case-insensitive lexicographical ordering of two strings.
14.Using the Comparable interface to compare and sort objects
15.Sort on many(more than one) fields
16.File Name Comparator
17.Comparator similar to String.CASE_INSENSITIVE_ORDER, but handles only ASCII characters
18.Natural Order Comparator
19.Reverse Order Comparator
20.A Comparator for Boolean objects that can sort either true or false first
21.Invertible Comparator
22.This program animates a sort algorithm