小编sak*_*029的帖子

我创建了一个GenericFunction实现Function和的类BiFunction.但它无法编译.

public class GenericFunction<T, U, R> implements
        Function<T, R>, BiFunction<T, U, R> {

    @Override
    public R apply(T t, U u) {
        return null;
    }

    @Override
    public R apply(T t) {
        return null;
    }

}

错误消息是:

src\obscure\test\GenericFunction.java:6: error:
types BiFunction<T,U,R> and Function<T,R> are incompatible;
both define andThen(java.util.function.Function<? super R,? extends V>),
but with unrelated return types
public class GenericFunction<T, U, R> implements
       ^
where T,U,R are type-variables:
  T extends Object declared in class GenericFunction
  U …