// patterns/PaperScissorsRock.java
// (c)2017 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.
// Demonstration of multiple dispatching
import java.util.*;
import java.util.function.*;
import java.util.stream.*;
import onjava.*;
import static onjava.Tuple.*;
enum Outcome { WIN, LOSE, DRAW }
interface Item {
Outcome compete(Item it);
Outcome eval(Paper p);
Outcome eval(Scissors s);
Outcome eval(Rock r);
}
class Paper implements Item {
@Override
public Outcome compete(Item it) {
return it.eval(this);
}
@Override
public Outcome eval(Paper p) {
return Outcome.DRAW;
}
@Override
public Outcome eval(Scissors s) {
return Outcome.WIN;
}
@Override
public Outcome eval(Rock r) {
return Outcome.LOSE;
}
@Override
public String toString() { return "Paper"; }
}
class Scissors implements Item {
@Override
public Outcome compete(Item it) {
return it.eval(this);
}
@Override
public Outcome eval(Paper p) {
return Outcome.LOSE;
}
@Override
public Outcome eval(Scissors s) {
return Outcome.DRAW;
}
@Override
public Outcome eval(Rock r) {
return Outcome.WIN;
}
@Override
public String toString() { return "Scissors"; }
}
class Rock implements Item {
@Override
public Outcome compete(Item it) {
return it.eval(this);
}
@Override
public Outcome eval(Paper p) {
return Outcome.WIN;
}
@Override
public Outcome eval(Scissors s) {
return Outcome.LOSE;
}
@Override
public Outcome eval(Rock r) {
return Outcome.DRAW;
}
@Override
public String toString() { return "Rock"; }
}
class ItemFactory {
static List