Aggregation/Composition code example

[Jacob Thomas]

Hi,

Could anyone please provide a detailed java code example to illustrate the implementaion of Aggregation and Composition? Thanks in advance!!!

[Vladas Razas]

Composition:

public class Customer {
  String name;
 
  public String getName() { return name; }
  public void setName(String name) { this.name = name; }

Aggregation:

public class SavingsAccount {
  Customer customer;
 
  public SavingsAccount(Customer customer) { this.customer = customer; }
}
 
public class CheckingAccount {
  Customer customer;
 
  public CheckingAccount(Customer customer) { this.customer = customer; }
}
 
public class AccountManager {
  public void fun() {
    Customer c = new Customer();
    // I want my customer to have 2 accounts for same customer. 
    // That makes 
    // any account aggregate customer. Account refers to 
    // customer but it doesn't own one. It's fun() method
    // who creates and owns them all. 
    CheckingAccount checking = new CheckingAccount(c);
    SavingsAccount savings= new SavingsAccount(c);
  }
}

[Ilja Preuss]

See http://faq.javaranch.com/view?AssociationVsAggregationVsComposition