FilesExpand file tree

 main

/

Exercise42.java

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

83 lines (72 loc) · 2.21 KB

 main

/

Exercise42.java

Copy path

Top

File metadata and controls

• Code
• Blame

83 lines (72 loc) · 2.21 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

import java.util.*;

interface Combiner<T> { T combine(T x, T y); }

interface UnaryFunction<R,T> { R function(T x); }

interface Collector<T> extends UnaryFunction<T,T> {

T result();

}

class Food {

private String foodName = "";

public Food() { foodName = ""; }

public Food(String name) { foodName = name; }

public void set(String name) { foodName = name; }

public String get() { return foodName; }

public void eat() { foodName = ""; }

public String toString() { return "Food: " + foodName; }

}

class Drink {

private String drinkName = "";

public Drink() { drinkName= ""; }

public Drink(String name) { drinkName = name; }

public void set(String name) { drinkName = name; }

public String get() { return drinkName; }

public void eat() { drinkName = ""; }

public String toString() { return "Drink: " + drinkName; }

}

class Functional42 {

public static <T> T

reduce(Iterable<T> seq, Combiner<T> combiner) {

Iterator<T> it = seq.iterator();

if(it.hasNext()) {

T result = it.next();

while(it.hasNext())

result = combiner.combine(result, it.next());

return result;

}

return null;

}

public static <T> Collector<T>

forEach(Iterable<T> seq, Collector<T> func) {

for(T t : seq) func.function(t);

return func;

}

static class MealMaker implements Combiner<Food> {

public Food combine(Food f1, Food f2) {

return new Food(f1.get() + " " + f2.get());

}

}

static class DrinkMaker implements Combiner<Drink> {

public Drink combine(Drink d1, Drink d2) {

return new Drink(d1.get() + " " + d2.get());

}

}

static class CookedMeal

implements Collector<Food> {

private Food f = new Food("");

public Food function(Food x) {

f = new Food(f.get() + " " + x.get());

return f;

}

public Food result() { return new Food("cooked " + f.get()); }

}

public static void main(String[] args) {

List<Food> lf = Arrays.asList(new Food("bread"),

new Food("ham"), new Food("cheese"));

Food meal = reduce(lf, new MealMaker());

System.out.println(meal);

List<Drink> ld = Arrays.asList(new Drink("water"),

new Drink("orange juice"), new Drink("lemon"));

Drink drink = reduce(ld, new DrinkMaker());

System.out.println(drink);

System.out.println(forEach(lf, new CookedMeal()).result());

}

}