// Doesn’t care about type, so new types
// added to the system still work right:
public static void tune(Instrument i) {
// ...
i.play(Note.MIDDLE_C);
}
public void perform() throws PerformanceException {
System.out.print("Playing " + song + " : ");
instrument.play();
}
public void perform() throws PerformanceException {
for (Instrument instrument : instruments) {
instrument.play();
}
}
