Re: Can a method be a parameter of another method in Java?

From:

"Ingo R. Homann" <ihomann_spam@web.de>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 14 Sep 2006 09:16:27 +0200

Message-ID:

<450901c9$0$26960$9b4e6d93@newsspool4.arcor-online.net>

Hi,

Shawn wrote:

/*
For testing passing a method as a method parameter
*/

interface Mapper {
  void map(int[] d);
}

class Test {

        void doSomethingToArray(Mapper m, int[] aArray) {
                m.map(aArray);
        } //end of method doSomethingToArray

        Mapper squareArray = new Mapper() {
                void map(int[] a)
                {
                        for (int i=0; i<a.length; i++)
                        {
                                a[i] *= a[i];
                        }
                }
        }

        Mapper printArray = new Mapper() {
                void map(int[] a)
                {
                        for (int i=0; i<a.length; i++)
                        {
                                System.out.println(a[i]);
                        }
                }
        }

Besides the missing ';', there is another design-flaw IMHO. I would do
it like this:

interface Mapper {
   int map(int a);
}

class Test {
   void doSomethingToArray(int[] as, Mapper m) {
     for(int i=0;i<as.length;i++) {
       as[i]=m.map(as[i]);
     }
   }
}

Mapper square=new Mapper() {
   int map(int i) {
     return i*i;
   }
}

Mapper print=new Mapper() {
   int map(int i) {
     System.out.println(i);
     return i; // (*)
   }
}

(*) here you can see, that "printing" is not really a kind of
"Mapper"-function.

Ciao,
Ingo