Java retrieve data from attribute classes

Question

I am new to objects and classes in java. I want to know how to get data from attribute objects. I have 4 classes

public class Personnel {
  private ArrayList<Employee> employees = new ArrayList<Employee>();

  public void addEmployee(Employee employee){
    employees.add(employee);
  }

  public ArrayList<Employee> getEmployees() {
    return this.employees;
  }

}

public class Employee{
  /**DATAFIELDS*/
  private String name;
  Address address;
  PayInfo pay;

  //Constructor
  //methods
  .....
}

public class PayInfo {
  /**DATAFIELDS*/
  private double salary;
  private boolean isFullTime;

  //Constructors
  //Methods
  ....
}

public class Address {
  /**DATAFIELDS*/
  private String streetAddress;
  private String city;
  private String state;
  private String zipCode;

  //Constructors
  //Methods
  .....
}

I have created payInfo and address objects and added to the employee object. And finally added that employee object to the Personnel object and saved in an ArrayList. But my question is, whether is there any way to retrieve all these information from just Personnel object rather than going through each objects ? Thanks in advance !! I mean i want something like this from my Main method,

public static void main(String[] args) {
    //Create CODPersonnel Object
    CODPersonnel personnelEmployee = new CODPersonnel();
    //Address Object for emp1 Object
    Address addressEmp1 = new Address();
    addressEmp1.setStreetAddress("637 67th Place");
    addressEmp1.setCity("Willowbrook");
    addressEmp1.setState("IL");
    addressEmp1.setZipCode("60527");

    //PayInfo for emp1 object
    PayInfo emp1PayInfo = new PayInfo();
    emp1PayInfo.setFullTime(true);
    emp1PayInfo.setSalary(85000.0);

    //Create the Employee object
    //and set attributes
    Employee emp1 = new Employee();
    emp1.setName("Samantha Simmons");
    emp1.setAddress(addressEmp1);
    emp1.setPay(emp1PayInfo);

    //Add objects to CODPersonnel objects
    personnelEmployee.addEmployee(emp1);
}

And i want to retrieve all information through Personnel object like,
System.out.println(personnelEmployee.getEmployees(......);

or, System.out.println(personnelEmployee.getAddress.streetName..etc,) something like that. I know it may sound stupid but is there any way like that??

Answer 1

Not sure what you're asking. You can access the information from the Employee objects in the ArrayList in Personnel, assuming you have the appropriate getters and setters in Employee that returns its PayInfo and Address.

Answer 2

You could put PayInfo and Address into a Details class. Each Employee could be composed of a Details object. You can then access the Details object from the Personnel class:

class Personnel {
    private Map<String, Employee> employees = new HashMap<>();

    public void addEmployee(Employee employee) {
        employees.put(employee.getName(), employee);
    }

    public Details getEmployeeDetails(String name) {
        return employees.get(name).getDetails();
    }
}

class Employee {
    private String name; //could be stored in Details
    private Details details;

    public Employee(String name, Details details) {
        this.details = details;
    }

    public Details getDetails() {
        return details;
    }

    public String getName() {
        return name;
    }
}

class Details {
    private PayInfo payInfo;
    private Address address;

    public Details(PayInfo payInfo, Address address) {
        this.payInfo = payInfo;
        this.address = address;
    }

    public PayInfo getPayInfo() {
        return payInfo;
    }

    public Address getAddress() {
        return address;
    }
}

I switched your List into a Map, so you can easily access each employee by name. You could then do:

public static void main(String[] args) {
    PayInfo info = ...;
    Address address = ...;
    Details details = new Details(info, address);

    String name = ...
    Employee employee = new Employee(name, details);

    Personnel personnel = new Personnel();
    personnel.addEmployee(employee);

    //example
    Details employeeDetails = personnel.getEmployeeDetails("Some Name");
    Address employeeAddress = employeeDetails.getAddress();
    System.out.println(employeeAddress.getStreetAddress());
}

This design strongly violates the Law of Demeter, so if you're looking for a design that doesn't violate it, I'll be more than happy to edit in a stronger design.