1package ds.util;
2
3abstract public
4 class Function<X,Y> {
5
6 abstract public Y apply(X x);
7
8
9
10 public static <X> Function<X,X> id() {
11 return
12 new Function<X,X>() {
13 public X apply(X x) {
14 return
15 x;
16 }
17 };
18 }
19
20
21
22 public static <X,Y> Function<X,Y> constF(Y c) {
23 return
24 new Const<X,Y>(c);
25 }
26
27 private static
28 class Const<X,Y> extends Function<X,Y> {
29 private final Y c;
30
31 public Const(Y c) { this.c = c; }
32
33 public Y apply(X x) {
34 return
35 c;
36 }
37 }
38}
Algorithmen & Datenstrukturen mit Java: ds.util.Function
