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

From:
Shawn <shaw@nospam.com>
Newsgroups:
comp.lang.java.programmer
Date:
Thu, 14 Sep 2006 08:57:46 -0400
Message-ID:
<eebjkb$lh8$1@news.nems.noaa.gov>
Ingo R. Homann wrote:

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


Thank you. Could you kindly provide "public static void main() " to show
me how to use it. As you see, I am a little lost here: in the same Java
file or in the different file? If in the same file, what the file name
should be?(Test.java or interface.java?) Do I have to make
doSomethingToArray static?

I still like my previous not-running program, because in yours, as you
said, Mapper print is "silly" and in the for loop inside
doSomethingToArray, as[i] = m.map(as[i]) is not needed in my program. My
code is more intuitive. The reason I want to pass a method as a
parameter into another method is to have more abstraction(clear mind
clutter). Your implementation brings other extra into the code. My goal
is half-achieved, though.

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