Task: Heronian triangles
C#: using System;
using System.Collections.Generic;

namespace heron
{
    class Program{
        static void Main(string[] args){           
            List<int[]> list = new List<int[]>();
            for (int c = 1; c <= 200; c++)
                for (int b = 1; b <= c; b++)
                    for (int a = 1; a <= b; a++)
                        if (gcd(a, gcd(b, c)) == 1 && isHeron(heronArea(a, b, c)))
                            list.Add(new int[] { a, b, c, a + b + c, (int)heronArea(a, b, c)});
            sort(list);
            Console.WriteLine("Number of primitive Heronian triangles with sides up to 200: " + list.Count + "\n\nFirst ten when ordered by increasing area, then perimeter,then maximum sides:\nSides\t\t\tPerimeter\tArea");
            for(int i = 0; i < 10; i++)
                Console.WriteLine(list[i][0] + "\t" + list[i][1] + "\t" + list[i][2] + "\t" + list[i][3] + "\t\t" + list[i][4]);
            Console.WriteLine("\nPerimeter = 210\nSides\t\t\tPerimeter\tArea");
            foreach (int[] i in list)
                if (i[4] == 210)
                    Console.WriteLine(i[0] + "\t" + i[1] + "\t" + i[2] + "\t" + i[3] + "\t\t" + i[4]);     
        }
        static bool isHeron(double heronArea){
            return heronArea % 1 == 0 && heronArea != 0;
        }
        static double heronArea(int a, int b, int c){
            double s = (a + b + c) / 2d;
            return Math.Sqrt(s * (s - a) * (s - b) * (s - c));
        }
        static int gcd(int a, int b){
            int remainder = 1, dividend, divisor;
            dividend = a > b ? a : b;
            divisor = a > b ? b : a;
            while (remainder != 0){
                remainder = dividend % divisor;
                if (remainder != 0){
                    dividend = divisor;
                    divisor = remainder;
                }
            }
            return divisor;
        }
        static void sort(List<int[]> list){
            int[] temp = new int[5];
            bool changed = true;
            while(changed){
                changed = false;
                for (int i = 1; i < list.Count; i++)
                    if (list[i][4] < list[i - 1][4] || list[i][4] == list[i - 1][4] && list[i][3] < list[i - 1][3]){
                        temp = list[i];
                        list[i] = list[i - 1];
                        list[i - 1] = temp;
                        changed = true;
                    }                
            }
        }
    }
}

Java: import java.util.ArrayList;

public class Heron {
    public static void main(String[] args) {
        ArrayList<int[]> list = new ArrayList<>();

        for (int c = 1; c <= 200; c++) {
            for (int b = 1; b <= c; b++) {
                for (int a = 1; a <= b; a++) {

                    if (gcd(gcd(a, b), c) == 1 && isHeron(heronArea(a, b, c))){
                        int area = (int) heronArea(a, b, c);
                        list.add(new int[]{a, b, c, a + b + c, area});
                    }
                }
            }
        }
        sort(list);

        System.out.printf("Number of primitive Heronian triangles with sides up "
                + "to 200: %d\n\nFirst ten when ordered by increasing area, then"
                + " perimeter:\nSides       Perimeter   Area", list.size());

        for (int i = 0; i < 10; i++) {
            System.out.printf("\n%d x %d x %d   %d      %d",
                    list.get(i)[0], list.get(i)[1], list.get(i)[2],
                    list.get(i)[3], list.get(i)[4]);
        }

        System.out.printf("\n\nArea = 210\nSides        Perimeter   Area");
        for (int i = 0; i < list.size(); i++) {
            if (list.get(i)[4] == 210)
                System.out.printf("\n%d x %d x %d   %d      %d",
                        list.get(i)[0], list.get(i)[1], list.get(i)[2],
                        list.get(i)[3], list.get(i)[4]);
        }
    }

    public static double heronArea(int a, int b, int c) {
        double s = (a + b + c) / 2f;
        return Math.sqrt(s * (s - a) * (s - b) * (s - c));
    }

    public static boolean isHeron(double h) {
        return h % 1 == 0 && h > 0;
    }

    public static int gcd(int a, int b) {
        int leftover = 1, dividend = a > b ? a : b, divisor = a > b ? b : a;
        while (leftover != 0) {
            leftover = dividend % divisor;
            if (leftover > 0) {
                dividend = divisor;
                divisor = leftover;
            }
        }
        return divisor;
    }

    public static void sort(ArrayList<int[]> list) {
        boolean swapped = true;
        int[] temp;
        while (swapped) {
            swapped = false;
            for (int i = 1; i < list.size(); i++) {
                if (list.get(i)[4] < list.get(i - 1)[4] ||
                        list.get(i)[4] == list.get(i - 1)[4] &&
                        list.get(i)[3] < list.get(i - 1)[3]) {
                    temp = list.get(i);
                    list.set(i, list.get(i - 1));
                    list.set(i - 1, temp);
                    swapped = true;
                }
            }
        }
    }
}