39 lines
770 B
Java
39 lines
770 B
Java
// polymorphism/CovariantReturn.java
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// (c)2020 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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class Grain {
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@Override
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public String toString() { return "Grain"; }
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}
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class Wheat extends Grain {
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@Override
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public String toString() { return "Wheat"; }
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}
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class Mill {
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Grain process() { return new Grain(); }
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}
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class WheatMill extends Mill {
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@Override
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Wheat process() { return new Wheat(); }
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}
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public class CovariantReturn {
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public static void main(String[] args) {
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Mill m = new Mill();
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Grain g = m.process();
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System.out.println(g);
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m = new WheatMill();
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g = m.process();
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System.out.println(g);
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}
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}
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/* Output:
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Grain
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Wheat
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*/
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