C#

using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;

public class MyGen
{
    private const string LL = "keygen";

    public virtual string getSerial(string userId, string licenseNum)
    {

        DateTime cal = new DateTime();
        cal.Add(1, 3);           // This is Java Code
        cal.Add(6, -1);          // This is Java Code

        NumberFormat nf = new java.text.DecimalFormat("000");                     // This is Java Code
        licenseNum = nf.format(Convert.ToInt32(licenseNum));                         // This is Java Code
        string verTime = new StringBuilder("-").Append(new java.text.SimpleDateFormat("yyMMdd").format(cal.getTime())).Append("0").ToString();                              // This is Java Code
        string type = "YE3MP-";
        string need = new StringBuilder(userId.Substring(0, 1)).Append(type).Append("300").Append(licenseNum).Append(verTime).ToString();
        string dx = new StringBuilder(need).Append(LL).Append(userId).ToString();
        int suf = this.decode(dx);
        string code = new StringBuilder(need).Append(Convert.ToString(suf)).ToString();
        return this.change(code);
    }

    private int decode(string s)
    {
        int i;
        char[] ac;
        int j;
        int k;
        i = 0;
        ac = s.ToCharArray();
        j = 0;
        k = ac.Length;
        while (j < k)
        {
            i = (31 * i) + ac[j];
            j++;
        }
        return Math.Abs(i);
    }

    private string change(string s)
    {
        sbyte[] abyte0;
        char[] ac;
        int i;
        int k;
        int j;
        abyte0 = s;                               // This is Java Code
        ac = new char[s.Length];
        i = 0;
        k = abyte0.Length;
        while (i < k)
        {
            j = abyte0[i];
            if ((j >= 48) && (j <= 57))
            {
                j = (((j - 48) + 5) % 10) + 48;
            }
            else if ((j >= 65) && (j <= 90))
            {
                j = (((j - 65) + 13) % 26) + 65;
            }
            else if ((j >= 97) && (j <= 122))
            {
                j = (((j - 97) + 13) % 26) + 97;
            }
            ac[i] = (char)j;
            i++;
        }
        return Convert.ToString(ac);
    }

    public MyGen()
        : base()
    {
    }

    static void Main(string[] args)
    {
        try
        {
            Console.WriteLine("please input register name:");
            string userId = null;
            userId = System.Console.ReadLine();
            MyGen MyGen = new MyGen();
            string res = MyGen.getSerial(userId, "5");
            Console.WriteLine("Serial:" + res);
            System.Console.ReadLine();
        }
        catch (IOException ex)
        {
        }
    }
}

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Threading;

namespace app
{
	public partial class Form1 : Form
	{
		private System.Drawing.Bitmap myBitmap;
		Thread newThread;
		public Form1()
		{
			InitializeComponent();
			newThread = new Thread(new ThreadStart(draw));
			newThread.Start();
		}

		private void Form1_Paint(object sender, PaintEventArgs e)
		{
			Graphics graphicsObj = e.Graphics;
			graphicsObj.DrawImage(myBitmap, 0, 0, myBitmap.Width, myBitmap.Height);
		}

		private void Form1_Load(object sender, EventArgs e)
		{
			myBitmap = new Bitmap(this.ClientRectangle.Width,
				this.ClientRectangle.Height,
				System.Drawing.Imaging.PixelFormat.Format24bppRgb);
		}
		public void draw()
		{
			Graphics gfx;
			gfx = Graphics.FromImage(myBitmap);
			Pen myPen = new Pen(System.Drawing.Color.Plum, 3);
		gfxLoop:
			for (int i = 1; i < 100; i++)
			{
				myPen.Color = Color.FromArgb(0, 0 + (i * 2), 0);
				gfx.DrawEllipse(myPen, 50 + i, 50 + i, 200 - (i * 2), 200 - (i * 2));
				Thread.Sleep(20);
				this.Invalidate();
			}
			for (int j = 0; j < 100; j++)
			{
				myPen.Color = Color.FromArgb(200 - (j * 2), 0, 100 - j);
				gfx.DrawEllipse(myPen, 150 - j, 150 - j, j * 2, j * 2);
				Thread.Sleep(20);
				this.Invalidate();
			}
			goto gfxLoop;
		}

		private void Form1_FormClosing(object sender, FormClosingEventArgs e)
		{
			newThread.Abort();
		}
	}
}