Task: Draw a rotating cube
C#: using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;
using System.Windows.Threading;

namespace RotatingCube
{
    public partial class Form1 : Form
    {
        double[][] nodes = {
            new double[] {-1, -1, -1}, new double[] {-1, -1, 1}, new double[] {-1, 1, -1},
            new double[] {-1, 1, 1}, new double[] {1, -1, -1}, new double[] {1, -1, 1},
            new double[] {1, 1, -1}, new double[] {1, 1, 1} };

        int[][] edges = {
            new int[] {0, 1}, new int[] {1, 3}, new int[] {3, 2}, new int[] {2, 0}, new int[] {4, 5},
            new int[] {5, 7}, new int[] {7, 6}, new int[] {6, 4}, new int[] {0, 4}, new int[] {1, 5},
            new int[] {2, 6}, new int[] {3, 7}};

        public Form1()
        {
            Width = Height = 640;
            StartPosition = FormStartPosition.CenterScreen;
            SetStyle(
                ControlStyles.AllPaintingInWmPaint |
                ControlStyles.UserPaint |
                ControlStyles.DoubleBuffer,
                true);

            Scale(100, 100, 100);
            RotateCuboid(Math.PI / 4, Math.Atan(Math.Sqrt(2)));

            var timer = new DispatcherTimer();
            timer.Tick += (s, e) => { RotateCuboid(Math.PI / 180, 0); Refresh(); };
            timer.Interval = new TimeSpan(0, 0, 0, 0, 17);
            timer.Start();
        }

        private void RotateCuboid(double angleX, double angleY)
        {
            double sinX = Math.Sin(angleX);
            double cosX = Math.Cos(angleX);

            double sinY = Math.Sin(angleY);
            double cosY = Math.Cos(angleY);

            foreach (var node in nodes)
            {
                double x = node[0];
                double y = node[1];
                double z = node[2];

                node[0] = x * cosX - z * sinX;
                node[2] = z * cosX + x * sinX;

                z = node[2];

                node[1] = y * cosY - z * sinY;
                node[2] = z * cosY + y * sinY;
            }
        }

        private void Scale(int v1, int v2, int v3)
        {
            foreach (var item in nodes)
            {
                item[0] *= v1;
                item[1] *= v2;
                item[2] *= v3;
            }
        }

        protected override void OnPaint(PaintEventArgs args)
        {
            var g = args.Graphics;
            g.SmoothingMode = SmoothingMode.HighQuality;
            g.Clear(Color.White);

            g.TranslateTransform(Width / 2, Height / 2);

            foreach (var edge in edges)
            {
                double[] xy1 = nodes[edge[0]];
                double[] xy2 = nodes[edge[1]];
                g.DrawLine(Pens.Black, (int)Math.Round(xy1[0]), (int)Math.Round(xy1[1]),
                        (int)Math.Round(xy2[0]), (int)Math.Round(xy2[1]));
            }

            foreach (var node in nodes)
            {
                g.FillEllipse(Brushes.Black, (int)Math.Round(node[0]) - 4,
                    (int)Math.Round(node[1]) - 4, 8, 8);
            }
        }
    }
}

Java: import java.awt.*;
import java.awt.event.ActionEvent;
import static java.lang.Math.*;
import javax.swing.*;

public class RotatingCube extends JPanel {
    double[][] nodes = {{-1, -1, -1}, {-1, -1, 1}, {-1, 1, -1}, {-1, 1, 1},
    {1, -1, -1}, {1, -1, 1}, {1, 1, -1}, {1, 1, 1}};

    int[][] edges = {{0, 1}, {1, 3}, {3, 2}, {2, 0}, {4, 5}, {5, 7}, {7, 6},
    {6, 4}, {0, 4}, {1, 5}, {2, 6}, {3, 7}};

    public RotatingCube() {
        setPreferredSize(new Dimension(640, 640));
        setBackground(Color.white);

        scale(100);
        rotateCube(PI / 4, atan(sqrt(2)));

        new Timer(17, (ActionEvent e) -> {
            rotateCube(PI / 180, 0);
            repaint();
        }).start();
    }

    final void scale(double s) {
        for (double[] node : nodes) {
            node[0] *= s;
            node[1] *= s;
            node[2] *= s;
        }
    }

    final void rotateCube(double angleX, double angleY) {
        double sinX = sin(angleX);
        double cosX = cos(angleX);

        double sinY = sin(angleY);
        double cosY = cos(angleY);

        for (double[] node : nodes) {
            double x = node[0];
            double y = node[1];
            double z = node[2];

            node[0] = x * cosX - z * sinX;
            node[2] = z * cosX + x * sinX;

            z = node[2];

            node[1] = y * cosY - z * sinY;
            node[2] = z * cosY + y * sinY;
        }
    }

    void drawCube(Graphics2D g) {
        g.translate(getWidth() / 2, getHeight() / 2);

        for (int[] edge : edges) {
            double[] xy1 = nodes[edge[0]];
            double[] xy2 = nodes[edge[1]];
            g.drawLine((int) round(xy1[0]), (int) round(xy1[1]),
                    (int) round(xy2[0]), (int) round(xy2[1]));
        }

        for (double[] node : nodes) 
            g.fillOval((int) round(node[0]) - 4, (int) round(node[1]) - 4, 8, 8);        
    }

    @Override
    public void paintComponent(Graphics gg) {
        super.paintComponent(gg);
        Graphics2D g = (Graphics2D) gg;
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);

        drawCube(g);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            JFrame f = new JFrame();
            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            f.setTitle("Rotating Cube");
            f.setResizable(false);
            f.add(new RotatingCube(), BorderLayout.CENTER);
            f.pack();
            f.setLocationRelativeTo(null);
            f.setVisible(true);
        });
    }
}