SE450: Midterm Practice: Composition/Map [6/28] Previous pageContentsNext page

For questions see the homework.

file:functions/one/Main.java [source] [doc-public] [doc-private]
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
package functions.one;
interface ArrFun {
  public int[] exec(int[] x);
}

interface IntFun {
  public int exec(int x);
}

class Abs implements IntFun {
  public int exec(int x) {
    //SAME AS: if (x < 0) return -x; else return x;
    return (x < 0) ? -x : x;
  }
}

class Cube implements IntFun {
  public int exec(int x) {
    return x*x*x;
  }
}

class Map implements ArrFun {
  IntFun f;
  public Map(IntFun f) { this.f = f; }
  public int[] exec(int[] x) {
    int[] answer = new int[x.length];
    for (int i=0; i<x.length; i++) {
      answer[i] = f.exec(x[i]);
    }
    return answer;
  }
}

class Main {
  public static void print(int[] x) {
    System.out.print("[ ");
    for (int i=0; i<x.length; i++)
      System.out.print(x[i]+ " ");
    System.out.println("]");
  }

  public static void main(String[] argv) {
    IntFun f = new Abs();
    System.out.println(f.exec(-5));

    int[] a = new int[10];
    for (int i=0; i<a.length; i++)
      a[i] = -i*10;

    ArrFun mabs = new Map(new Comp(new Abs(), new Cube()));
    print(mabs.exec(a));
  }
}

class Comp implements IntFun {
  IntFun f, g;
  public Comp(IntFun f, IntFun g) { this.f = f; this.g = g; }
  public int exec(int x) {
    return g.exec(f.exec(x));
  }
}

Previous pageContentsNext page