20 lines
683 B
Java
20 lines
683 B
Java
// generics/GenericsAndCovariance.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://mindviewinc.com/Books/OnJava/ for more book information.
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import java.util.*;
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public class GenericsAndCovariance {
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public static void main(String[] args) {
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// Wildcards allow covariance:
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List<? extends Fruit> flist = new ArrayList<>();
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// Compile Error: can't add any type of object:
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// flist.add(new Apple());
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// flist.add(new Fruit());
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// flist.add(new Object());
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flist.add(null); // Legal but uninteresting
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// We know that it returns at least Fruit:
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Fruit f = flist.get(0);
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}
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}
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