//: Music4.java
//////////////////////////////////////////////////
// Copyright (c) Bruce Eckel, 1998
// Source code file from the book "Thinking in Java"
// All rights reserved EXCEPT as allowed by the
// following statements: You can freely use this file
// for your own work (personal or commercial),
// including modifications and distribution in
// executable form only. Permission is granted to use
// this file in classroom situations, including its
// use in presentation materials, as long as the book
// "Thinking in Java" is cited as the source.
// Except in classroom situations, you cannot copy
// and distribute this code; instead, the sole
// distribution point is http://www.BruceEckel.com
// (and official mirror sites) where it is
// freely available. You cannot remove this
// copyright and notice. You cannot distribute
// modified versions of the source code in this
// package. You cannot use this file in printed
// media without the express permission of the
// author. Bruce Eckel makes no representation about
// the suitability of this software for any purpose.
// It is provided "as is" without express or implied
// warranty of any kind, including any implied
// warranty of merchantability, fitness for a
// particular purpose or non-infringement. The entire
// risk as to the quality and performance of the
// software is with you. Bruce Eckel and the
// publisher shall not be liable for any damages
// suffered by you or any third party as a result of
// using or distributing software. In no event will
// Bruce Eckel or the publisher be liable for any
// lost revenue, profit, or data, or for direct,
// indirect, special, consequential, incidental, or
// punitive damages, however caused and regardless of
// the theory of liability, arising out of the use of
// or inability to use software, even if Bruce Eckel
// and the publisher have been advised of the
// possibility of such damages. Should the software
// prove defective, you assume the cost of all
// necessary servicing, repair, or correction. If you
// think you've found an error, please email all
// modified files with clearly commented changes to:
// Bruce@EckelObjects.com. (Please use the same
// address for non-code errors found in the book.)
/////////////////////////////////////////////////
// Abstract classes and methods
import java.util.*;
abstract class Instrument4 {
int i; // storage allocated for each
public abstract void play();
public String what() {
return "Instrument4";
}
public abstract void adjust();
}
class Wind4 extends Instrument4 {
public void play() {
System.out.println("Wind4.play()");
}
public String what() { return "Wind4"; }
public void adjust() {}
}
class Percussion4 extends Instrument4 {
public void play() {
System.out.println("Percussion4.play()");
}
public String what() { return "Percussion4"; }
public void adjust() {}
}
class Stringed4 extends Instrument4 {
public void play() {
System.out.println("Stringed4.play()");
}
public String what() { return "Stringed4"; }
public void adjust() {}
}
class Brass4 extends Wind4 {
public void play() {
System.out.println("Brass4.play()");
}
public void adjust() {
System.out.println("Brass4.adjust()");
}
}
class Woodwind4 extends Wind4 {
public void play() {
System.out.println("Woodwind4.play()");
}
public String what() { return "Woodwind4"; }
}
public class Music4 {
// Doesn't care about type, so new types
// added to the system still work right:
static void tune(Instrument4 i) {
// ...
i.play();
}
static void tuneAll(Instrument4[] e) {
for(int i = 0; i < e.length; i++)
tune(e[i]);
}
public static void main(String[] args) {
Instrument4[] orchestra = new Instrument4[5];
int i = 0;
// Upcasting during addition to the array:
orchestra[i++] = new Wind4();
orchestra[i++] = new Percussion4();
orchestra[i++] = new Stringed4();
orchestra[i++] = new Brass4();
orchestra[i++] = new Woodwind4();
tuneAll(orchestra);
}
} ///:~ |