Convex Hull in Java

Welcome to the Convex Hull in Java page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

import java.util.*;

public class ConvexHull {
    public static void main(String[] args) {
        if (args.length < 2)
            System.out.println(
                    "Usage: please provide at least 3 x and y coordinates as separate lists (e.g. \"100, 440, 210\")");
        else {
            String xInput = args[0];
            String yInput = args[1];
            String[] tempX = xInput.split(", ");
            String[] tempY = yInput.split(", ");
            if (tempX.length != tempY.length || tempX.length < 3) {
                System.out.println(
                        "Usage: please provide at least 3 x and y coordinates as separate lists (e.g. \"100, 440, 210\")");
                return;
            }
            Point[] points = new Point[tempX.length];
            int minX = Integer.MAX_VALUE;
            int mindex = 0;
            for (int a = 0; a < tempX.length; a++) {
                if (!tempX[a].matches("-?\\d+") || !tempY[a].matches("-?\\d+")) {
                    System.out.println(
                            "Usage: please provide at least 3 x and y coordinates as separate lists (e.g. \"100, 440, 210\")");
                    return;
                }
                points[a] = new Point(Integer.parseInt(tempX[a]), Integer.parseInt(tempY[a]));
                if (points[a].x <= minX) {
                    minX = points[a].x;
                    mindex = a;
                }
            }
            Stack<Point> result = new Stack<Point>();
            int considerdex = mindex;
            do {
                result.push(points[considerdex]);
                int nextdex = (considerdex + 1) % points.length;
                for (int contenderdex = 0; contenderdex < points.length; contenderdex++) {
                    if (isCounterClockwise(points[considerdex], points[nextdex], points[contenderdex]))
                        nextdex = contenderdex;
                }
                considerdex = nextdex;
            } while (considerdex != mindex);
            int k = result.size();
            for (int a = 0; a < k; a++) {
                System.out.println(result.pop().toString());
            }
        }
    }

    public static boolean isCounterClockwise(Point a, Point b, Point c) {
        return (c.y - a.y) * (b.x - a.x) > (b.y - a.y) * (c.x - a.x);
    }
}

class Point {
    public int x;
    public int y;

    public Point(int a, int b) {
        x = a;
        y = b;
    }

    public String toString() {
        return "(" + x + ", " + y + ")";
    }
}

Convex Hull in Java was written by:

• Jeremy Grifski
• jsonW0

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

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How to Run the Solution

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