Composite and aggregation code example - is this correct

Question

after reading all the aggregation and composition of this forum threads, i would like to know whether this is the corect understading in java implmentation of composite and aggregation.
example of aggregation
public class Money{}
public class Wallet {
private Money money;
public Wallet(Money money) {
this.money = money;
example of composite
public class Heart {}
public class Human {
private Heart heart;
private Human() {
heart = new Heart();
the aggregation implementation is based on the idea " The instance of aggregated class can be shared by many other classes. While those classes are deleted, the instance of aggreated class won't be deleted."
hence, i create money object outside the wallet, the passed the money into the wallet to make them "has a" relationship.
the composite implementation is based on the idea " the instance of composited class can only be used by one other class. While that class is deleted. The composited class will also be deleted."
hence, the creattion of heart is done by the human constructor it self.
1. is this the only ways to do the implementation for composite and aggregation?
2. is there other implementations for aggregation, the money class is constructed inside the wallet class?
3. is there other implementations for composition, the heart class is constructed outside the human class?
thank you very much!

Answer 1

Your abstractions are quite good.
1. is this the only ways to do the implementation for composite and aggregation?Broadly speaking yes, there are as some subtle variations, but you examples illustrate the key distinction.
2. is there other implementations for aggregation, the money class is constructed inside the wallet class?Yes, in practice you should also have methods to add and remove from an abstraction, so Wallet should have Wallet.add(Money) and Wallet.remove(Money) methods. You should also consider multiplicity, which may require that you use Qualified Classes and/or Associative Classes to implment an aggregation.
No, you should not construct the Money inside the Wallet. If you find you want to do this you should consider changing to a Composite.
3. is there other implementations for composition, the heart class is constructed outside the human class?Yes, it is usual to pass a this from the Composite (Human) to the part (Heart) when you construct it because Composition is implicitly a bi-directional relationship.
No the part of a composite should not be constructed outside the composite.