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