Issue with “Math.random()” in Java

Question

I want to write a code that draws some specific points on a window. I have 3 different points $(e1,e11), (e2,e22), (e3,e33)$. I want to randomly choose one of them and depending on the output, draw a different point.

public class ChaosGame {

    public static void main(String[] args) {
        Window window = new Window("Chaos", 800, 800);
        window.open();

        int e1 = 420;
        int e11 = 170;
        int e2 = 230;
        int e22 = 670;
        int e3 = 700;
        int e33 = 540;

        while (window.isOpen()) {// ändere den Fensterinhalt
            int pos1 = 100;
            int pos2 = 300;
            int i = (int) (Math.random() * 3);

            if (i == 0 || i == 3) {
                window.fillRect(pos1 + e1 / 2, pos2 + e11 / 2, 5, 5);
                pos1 = e1 / 2;
                pos2 = e11 / 2;
                window.refresh();
            } else if (i == 1) {
                window.fillRect(pos1 + e2 / 2, pos2 + e22 / 2, 5, 5);
                pos1 = e2 / 2;
                pos2 = e22 / 2;
                window.refresh();
            } else {
                window.fillRect(pos1 + e3 / 2, pos2 + e33 / 2, 5, 5);
                pos1 = e3 / 2;
                pos2 = e33 / 2;
                window.refresh();
            }
        }
    }
}

fillRect draws my points in the new window. Now when I run this program, only two points appear, even though it should go on "while window.isOpen" so until I close the window. I think something with my Math.random() might be wrong.

Answer 1

You need to change the window.fillRect(pos1 + e2 / 2, pos2 + e22 / 2, 5, 5); to window.fillRect(pos1 + e3 / 2, pos2 + e33 / 2, 5, 5); in the else statement. You are drawing the same stuff in two cases.