Write a program to print squares of integers up to 25 in java without using variables?

Question

I asked this question on programmers 10 days back but wasn't able to get the answer that I wanted.

Write program in java to print the squares of first 25 integers(1-25) without using any variables.

I am not looking for any theory explaining concepts about java or functional programming. I just want to know if its possible in java, the way the author has described in the original context.

--------Edit-------------------- Actually making it mutable variable makes it quite easy. The original context was

(take 25 (squares-of (integers))) Notice that it has no variables. Indeed, it has nothing more than three functions and one constant. Try writing the squares of integers in Java without using a variable. Oh, there’s probably a way to do it, but it certainly isn’t natural, and it wouldn’t read as nicely as my program above.

So try writing same program without using any variables.

Answer 1

Ugly hack in 216 characters, this does not even use method args:

class M{static void m(){System.out.println((Thread.currentThread().getStackTrace().length-2)*(Thread.currentThread().getStackTrace().length-2));if(Thread.currentThread().getStackTrace().length-2<25)m();}static {m();}}

Formatted, this looks like:

class M {
    static void m()
    {
        System.out.println((Thread.currentThread().getStackTrace().length-2)*(Thread.currentThread().getStackTrace().length-2));
        if (Thread.currentThread().getStackTrace().length-2 < 25) m();
    }
    public static void main(String[] a)
    {
        m();
    }
    // We can comply fully with the question (no variables),
    // but then cannot avoid the "java.lang.NoSuchMethodError: main":
    static 
    {
        m();
    }
}

For those who don't understand: It takes the stacks length squares it. This works because I'm recursively calling m(), always increasing the stack by 1. Maybe this could be written even shorter.

Answer 2

Obligatory cheat:

public class PrintTwentyFiveSquares {

    public static void main() {
        System.out.println("1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196, 225, 256, 289, 324, 361, 400, 441, 484, 529, 576, 625");
    }

}

Answer 3

How about this?

public class Squares {
    public static void printSquares(final int n) {
        if (n > 1) {
            printSquares(n - 1);
        }
        System.out.println(n * n);
    }

    public static void main(final String... args) {
        printSquares(25);
    }
}

Now that you completely changed the question, my solution depends on whether you consider function arguments to be variables or not. I'd say it still stands.

I should add that the Closure solution depends on the pre-availability of several functions in the standard library. The same functions could be written in Java, leading to a nearly identical main program:

import java.util.AbstractList;
import java.util.List;

public class Squares2 {
    public static List<Integer> integers() {
        return new AbstractList<Integer>() {
            @Override
            public Integer get(final int index) {
                return index + 1;
            }

            @Override
            public int size() {
                return Integer.MAX_VALUE;
            }
        };
    }

    public static List<Integer> squaresOf(final List<Integer> l) {
        return new AbstractList<Integer>() {
            @Override
            public Integer get(final int index) {
                return l.get(index) * l.get(index);
            }

            @Override
            public int size() {
                return l.size();
            }
        };
    }

    public static List<Integer> take(final int n, final List<Integer> l) {
        return l.subList(0, n);
    }

    public static void main(final String... args) {
        System.out.println(take(25, squaresOf(integers())));
    }
}