Task: Draw a cuboid
Go: package main

import "fmt"

func cuboid(dx, dy, dz int) {
    fmt.Printf("cuboid %d %d %d:\n", dx, dy, dz)
    cubLine(dy+1, dx, 0, "+-")
    for i := 1; i <= dy; i++ {
        cubLine(dy-i+1, dx, i-1, "/ |")
    }
    cubLine(0, dx, dy, "+-|")
    for i := 4*dz - dy - 2; i > 0; i-- {
        cubLine(0, dx, dy, "| |")
    }
    cubLine(0, dx, dy, "| +")
    for i := 1; i <= dy; i++ {
        cubLine(0, dx, dy-i, "| /")
    }
    cubLine(0, dx, 0, "+-\n")
}

func cubLine(n, dx, dy int, cde string) {
    fmt.Printf("%*s", n+1, cde[:1])
    for d := 9*dx - 1; d > 0; d-- {
        fmt.Print(cde[1:2])
    }
    fmt.Print(cde[:1])
    fmt.Printf("%*s\n", dy+1, cde[2:])
}

func main() {
    cuboid(2, 3, 4)
    cuboid(1, 1, 1)
    cuboid(6, 2, 1)
}

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

public class Cuboid 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}};

    int mouseX, prevMouseX, mouseY, prevMouseY;

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

        scale(80, 120, 160);
        rotateCube(PI / 5, PI / 9);

        addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                mouseX = e.getX();
                mouseY = e.getY();
            }
        });

        addMouseMotionListener(new MouseAdapter() {
            @Override
            public void mouseDragged(MouseEvent e) {
                prevMouseX = mouseX;
                prevMouseY = mouseY;
                mouseX = e.getX();
                mouseY = e.getY();

                double incrX = (mouseX - prevMouseX) * 0.01;
                double incrY = (mouseY - prevMouseY) * 0.01;

                rotateCube(incrX, incrY);
                repaint();
            }
        });
    }

    private void scale(double sx, double sy, double sz) {
        for (double[] node : nodes) {
            node[0] *= sx;
            node[1] *= sy;
            node[2] *= sz;
        }
    }

    private 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("Cuboid");
            f.setResizable(false);
            f.add(new Cuboid(), BorderLayout.CENTER);
            f.pack();
            f.setLocationRelativeTo(null);
            f.setVisible(true);
        });
    }
}