This program is in java I need help please.

public class Order {

private int nr;

public Order() {

. . .

}

}

public class Item {

. . .

String productName;

float productPrice;

public Item() {

. . .

}

}

How we would implement this relationship in these two classes.

What syntax is used in the declaration of a class that is the type of the objects that will be written as a sequence of bytes