import java.util.ArrayList; | |
import java.util.List; | |
class Collector<C> { | |
} | |
interface S<T> { | |
/** | |
* Gets a result. | |
* | |
* @return a result | |
*/ | |
T get(); | |
} | |
interface F<TF> {} | |
final class Collectors { | |
public static <T> | |
Collector<List<T>> toList() { | |
return null; | |
} | |
public static <K1> Collector<ArrayList<K1>> groupingBy(F<K1> classifier) { | |
return groupingBy(classifier, ArrayList ::new); | |
} | |
public static <K, M extends ArrayList<K>> | |
Collector<M> groupingBy(F<K> classifier, | |
S<M> mapFactory) { | |
return null; | |
} | |
} |