import java.util.*; | |
class A { | |
private void foo(Stream<String> a) { | |
Map<String, List<String>> temp = a.collect(groupingBy(Function.<String>identity())); | |
} | |
interface Collector<T, A, R> { | |
} | |
public static <T, K> Collector<T, ?, Map<K, List<T>>> groupingBy(Function<? super T, ? extends K> classifier) { | |
return null; | |
} | |
interface Stream<T> { | |
<R, A> R collect(Collector<? super T, A, R> collector); | |
} | |
interface Function<A, B> { | |
B fn(A a); | |
static <T> Function<T, T> identity() { | |
return t -> t; | |
} | |
} | |
} |