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kmizu/DiamondOperators.java

Created July 31, 2011 16:10
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By using diamond operator, type inference is done correctly.
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DiamondOperators.java
import java.util.*;
public class DiamondOperators {
public static void main(String[] args) {
Collection<? extends Number> collection = null;
List<? super String> list = new ArrayList<>(collection);
}
}
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kmizu commented Jul 31, 2011 

mizushima@ubuntu:~$ javac DiamondOperators.java
DiamondOperators.java:5: error: incompatible types
    List<? super String> list = new ArrayList<>(collection);
                                ^
  required: List<? super String>
  found:    ArrayList<Number>
1 error

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