// functional/TransformFunction.java

// (c)2021 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

import java.util.function.Function;

class I {

@Override

public String toString() {

return "I";

}

}

class O {

@Override

public String toString() {

return "O";

}

}

public class TransformFunction {

static Function<I, O> transform(Function<I, O> in) {

return in.andThen(o -> {

System.out.println(o);

return o;

});

}

public static void main(String[] args) {

Function<I, O> f2 = transform(i -> {

System.out.println(i);

return new O();

});

O o = f2.apply(new I());

}

}

/* Output:

I

O

*/