73 lines
1.9 KiB
Java
73 lines
1.9 KiB
Java
// generics/EpicBattle.java
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// (c)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://OnJava8.com for more book information.
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// Bounds in Java generics
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import java.util.*;
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interface SuperPower {}
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interface XRayVision extends SuperPower {
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void seeThroughWalls();
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}
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interface SuperHearing extends SuperPower {
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void hearSubtleNoises();
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}
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interface SuperSmell extends SuperPower {
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void trackBySmell();
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}
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class SuperHero<POWER extends SuperPower> {
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POWER power;
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SuperHero(POWER power) { this.power = power; }
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POWER getPower() { return power; }
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}
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class SuperSleuth<POWER extends XRayVision>
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extends SuperHero<POWER> {
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SuperSleuth(POWER power) { super(power); }
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void see() { power.seeThroughWalls(); }
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}
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class CanineHero<POWER extends SuperHearing & SuperSmell>
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extends SuperHero<POWER> {
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CanineHero(POWER power) { super(power); }
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void hear() { power.hearSubtleNoises(); }
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void smell() { power.trackBySmell(); }
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}
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class SuperHearSmell implements SuperHearing, SuperSmell {
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@Override
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public void hearSubtleNoises() {}
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@Override
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public void trackBySmell() {}
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}
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class DogPerson extends CanineHero<SuperHearSmell> {
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DogPerson() { super(new SuperHearSmell()); }
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}
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public class EpicBattle {
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// Bounds in generic methods:
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static <POWER extends SuperHearing>
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void useSuperHearing(SuperHero<POWER> hero) {
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hero.getPower().hearSubtleNoises();
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}
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static <POWER extends SuperHearing & SuperSmell>
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void superFind(SuperHero<POWER> hero) {
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hero.getPower().hearSubtleNoises();
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hero.getPower().trackBySmell();
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}
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public static void main(String[] args) {
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DogPerson dogPerson = new DogPerson();
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useSuperHearing(dogPerson);
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superFind(dogPerson);
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// You can do this:
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List<? extends SuperHearing> audioPeople;
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// But you can't do this:
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// List<? extends SuperHearing & SuperSmell> dogPs;
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}
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}
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