Design Patterns Java™ Workbook

Chapter 12. Chain of Responsibility

CHALLENGE 12.4

Fill in the constructors in Figure 12.2 to support a design that ensures that every

MachineComponent object has a responsible engineer.

Figure 12.2. How can constructors ensure that every MachineComponent

object has a responsible engineer?

By anchoring a chain of responsibility, you strengthen the object model and simplify the code.
Now you can implement the getResponsible() method of MachineComponent as:

public Engineer getResponsible()
{
if (responsible != null)
{
return responsible;
}
return parent.getResponsible();
}