39 lines
1.1 KiB
Java
39 lines
1.1 KiB
Java
// collections/ApplesAndOrangesWithoutGenerics.java
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// (c)2017 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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// Simple collection use (suppressing compiler warnings)
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// {ThrowsException}
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import java.util.*;
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class Apple {
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private static long counter;
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private final long id = counter++;
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public long id() { return id; }
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}
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class Orange {}
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public class ApplesAndOrangesWithoutGenerics {
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@SuppressWarnings("unchecked")
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public static void main(String[] args) {
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ArrayList apples = new ArrayList();
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for(int i = 0; i < 3; i++)
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apples.add(new Apple());
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// No problem adding an Orange to apples:
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apples.add(new Orange());
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for(Object apple : apples) {
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((Apple) apple).id();
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// Orange is detected only at run time
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}
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}
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}
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/* Output:
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___[ Error Output ]___
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Exception in thread "main"
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java.lang.ClassCastException: Orange cannot be cast to
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Apple
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at ApplesAndOrangesWithoutGenerics.main(ApplesA
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ndOrangesWithoutGenerics.java:23)
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*/
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