Design Patterns Java™ Workbook

Chapter 10. Mediator

public Machine getMachine(Tub t)
{
return (Machine) tubToMachine.get(t);
}

public Set getTubs(Machine m)
{
Set set = new HashSet();
Iterator i = tubToMachine.entrySet().iterator();
while (i.hasNext())
{
Map.Entry e = (Map.Entry) i.next();
if (e.getValue().equals(m))
{
set.add(e.getKey());
}
}
return set;
}

public void set(Tub t, Machine m)
{
tubToMachine.put(t, m);
}
}

Figure 10.6. The Mediator pattern lets you define an object that encapsulates how tubs and
machines interact.

CHALLENGE 10.4

Write the code for the Tub methods getMachine() and setMachine().