public void undo()
{
if (previousSpeed == CeilingFan.HIGH)
{
ceilingFan.high();
}
else if (previousSpeed == CeilingFan.MEDIUM)
{
ceilingFan.medium();
}
else if (previousSpeed == CeilingFan.LOW)
{
ceilingFan.low();
}
else if (previousSpeed == CeilingFan.OFF)
{
ceilingFan.off();
}
}
public void excute()
{
previousSpeed = ceilingFan.getSpeed();
ceilingFan.low();
}