Scala Collections Demo

Employee.java

public class Employee {
  private Address addr;
  private int age;
  
  // Getters and setters
}

class Address {
  private String streetAddr1;
  private String streetAddr2;
  private String city;
  private int zipCode;
  private String state;
  
  // Getters and setters
}

HR.java

public class HR {
  private List<Employee> allEmployees = // HR knows how to find you
  
  public static List<Employee> findAllEmployeesLivingInZipCode(int zipCode) {
    List<Employee> employees = new ArrayList<>();
    
    for (Employee e : allEmployees) {
      if (e.getAddr().getzipCode() == zipCode) {
        employees.add(e);
      }
    }
    
    return employees;
  }
  
  public static int getAverageAge() {
    long sum = 0;
    
    for (Employee e : allEmployees) {
      sum += e.getAge();
    }
    
    return sum / allEmployees.size();
  }
}

HR.scala

object HR {
  List[Employee] allEmployees = // HR knows how to find you
  
  def findAllEmployeesLivingInZipCode(zipCode: Int) = {
    allEmployees.filter(_.addr.zipCode == zipCode)
  }
  
  def getAverageAge = {
    allEmployees.map(_.age).sum / allEmployees.size
  }
}