90 lines
2.1 KiB
Java
90 lines
2.1 KiB
Java
// interfaces/music5/Music5.java
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// ©2016 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
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// Interfaces.
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package interfaces.music5;
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import polymorphism.music.Note;
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interface Instrument {
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// Compile-time constant:
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int VALUE = 5; // static & final
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// Cannot have method definitions:
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void play(Note n); // Automatically public
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void adjust();
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}
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class Wind implements Instrument {
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@Override
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public void play(Note n) {
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System.out.println(this + ".play() " + n);
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}
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@Override
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public String toString() { return "Wind"; }
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@Override
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public void adjust() { System.out.println(this + ".adjust()"); }
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}
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class Percussion implements Instrument {
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@Override
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public void play(Note n) {
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System.out.println(this + ".play() " + n);
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}
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@Override
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public String toString() { return "Percussion"; }
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@Override
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public void adjust() { System.out.println(this + ".adjust()"); }
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}
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class Stringed implements Instrument {
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@Override
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public void play(Note n) {
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System.out.println(this + ".play() " + n);
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}
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@Override
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public String toString() { return "Stringed"; }
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@Override
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public void adjust() { System.out.println(this + ".adjust()"); }
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}
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class Brass extends Wind {
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@Override
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public String toString() { return "Brass"; }
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}
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class Woodwind extends Wind {
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@Override
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public String toString() { return "Woodwind"; }
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}
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public class Music5 {
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// Doesn't care about type, so new types
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// added to the system still work right:
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static void tune(Instrument i) {
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// ...
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i.play(Note.MIDDLE_C);
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}
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static void tuneAll(Instrument[] e) {
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for(Instrument i : e)
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tune(i);
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}
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public static void main(String[] args) {
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// Upcasting during addition to the array:
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Instrument[] orchestra = {
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new Wind(),
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new Percussion(),
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new Stringed(),
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new Brass(),
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new Woodwind()
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};
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tuneAll(orchestra);
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}
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}
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/* Output:
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Wind.play() MIDDLE_C
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Percussion.play() MIDDLE_C
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Stringed.play() MIDDLE_C
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Brass.play() MIDDLE_C
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Woodwind.play() MIDDLE_C
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*/
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