01
02
03
04
05
06
07
08
09
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
|
package functions.two;
interface Stream {
int next();
}
class IntStream implements Stream {
private int i = -1;
public int next() {
return ++i;
}
}
interface Predicate{
boolean evaluate(int j);
}
class FilteredStream implements Stream{
private Stream it;
private Predicate p;
public FilteredStream(Stream it, Predicate p) {
this.it = it;
this.p =p;
}
public int next() {
int i;
do {
i = it.next();
} while (!p.evaluate(i));
return i;
}
}
class IsEven implements Predicate {
public boolean evaluate(int j){
return (j%2)== 0;
}
}
class Main {
public static void main (String[] args) {
IntStream I = new IntStream();
FilteredStream F = new FilteredStream(I, new IsEven());
System.out.println(F.next()); // prints 0 on the screen
System.out.println(F.next()); // prints 2 on the screen
System.out.println(F.next()); // prints 4 on the screen
System.out.println(F.next()); // prints 6 on the screen
System.out.println(F.next()); // prints 8 on the screen
IntStream J = new IntStream();
J.next(); // move forward one item in J
FilteredStream G = new FilteredStream(J, new IsEven());
System.out.println(G.next()); // prints 2 on the screen
System.out.println(G.next()); // prints 4 on the screen
System.out.println(G.next()); // prints 6 on the screen
System.out.println(G.next()); // prints 8 on the screen
IntStream K = new IntStream();
class Div3 implements Predicate {
public boolean evaluate(int n) { return (n%3) == 0; }
}
FilteredStream H = new FilteredStream(K, new Div3());
System.out.println(H.next()); // prints 0 on the screen
System.out.println(H.next()); // prints 3 on the screen
System.out.println(H.next()); // prints 6 on the screen
System.out.println(H.next()); // prints 9 on the screen
}
}
|
