Solutions - Design Patterns Java - page 312

SOLUTION 12.3
A. A MachineComponent object may have an explicitly assigned responsible person. If
it doesn't, it passes the request to its parent:
public Engineer getResponsible()
{
if (responsible != null)
{
return responsible;
}
if (parent != null)
{
return parent.getResponsible();
}
return null;
}
B. The code for Tool.getResponsibility() reflects the statement that "tools are
always assigned to tool carts":
public Engineer getResponsible()
{
return toolCart.getResponsible();
}
C. The ToolCart code reflects the statement that "tool carts have a responsible
engineer":
public Engineer getResponsible()
{
return responsible;
}
SOLUTION 12.4
Your solution should look something like Figure B.17. Your constructors should allow
Machine and MachineComposite objects to be instantiated with or without an assigned
engineer. Whenever a MachineComponent object does not have an assigned engineer, it
can get a responsible engineer from its parent.