Company and Employee : Comparator « Collections Data Structure « Java

Company and Employee

import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Set;
import java.util.TreeSet;

public class Company {
  public static void main(String args[]) {
    Employee emps[] = { new Employee("Finance", "Degree, Debbie"),
        new Employee("Finance", "Grade, Geri"),
        new Employee("Finance", "Extent, Ester"),
        new Employee("Engineering", "Measure, Mary"),
        new Employee("Engineering", "Amount, Anastasia"),
        new Employee("Engineering", "Ratio, Ringo"),
        new Employee("Sales", "Stint, Sarah"),
        new Employee("Sales", "Pitch, Paula"),
        new Employee("Support", "Rate, Rhoda"), };
    Set set = new TreeSet(Arrays.asList(emps));
    Set set2 = new TreeSet(Collections.reverseOrder());

    Set set3 = new TreeSet(new EmpComparator());
    for (int i = 0, n = emps.length; i < n; i++) {

class EmpComparator implements Comparator {

  public int compare(Object obj1, Object obj2) {
    Employee emp1 = (Employee) obj1;
    Employee emp2 = (Employee) obj2;

    int nameComp = emp1.getName().compareTo(emp2.getName());

    return ((nameComp == 0) ? emp1.getDepartment().compareTo(
        emp2.getDepartment()) : nameComp);

class Employee implements Comparable {
  String department, name;

  public Employee(String department, String name) {
    this.department = department; = name;

  public String getDepartment() {
    return department;

  public String getName() {
    return name;

  public String toString() {
    return "[dept=" + department + ",name=" + name + "]";

  public int compareTo(Object obj) {
    Employee emp = (Employee) obj;
    int deptComp = department.compareTo(emp.getDepartment());

    return ((deptComp == 0) ? name.compareTo(emp.getName()) : deptComp);

  public boolean equals(Object obj) {
    if (!(obj instanceof Employee)) {
      return false;
    Employee emp = (Employee) obj;
    return department.equals(emp.getDepartment())
        && name.equals(emp.getName());

  public int hashCode() {
    return 31 * department.hashCode() + name.hashCode();


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