MyEclipse 8.5レジストリコード生成コード

import java.io.*;    

public class MyEclipseGen {    

    private static final String LL = "Decompiling this copyrighted software is a violation of both your license agreement and the Digital Millenium Copyright Act of 1998 (http://www.loc.gov/copyright/legislation/dmca.pdf). Under section 1204 of the DMCA, penalties range up to a $500,000 fine or up to five years imprisonment for a first offense. Think about it; pay for a license, avoid prosecution, and feel better about yourself.";    

    public String getSerial(String userId, String licenseNum) {    

        java.util.Calendar cal = java.util.Calendar.getInstance();    

        cal.add(1, 3);    

        cal.add(6, -1);    

        java.text.NumberFormat nf = new java.text.DecimalFormat("000");    

        licenseNum = nf.format(Integer.valueOf(licenseNum));    

        String verTime = new StringBuilder("-").append(    

                new java.text.SimpleDateFormat("yyMMdd").format(cal.getTime()))    

                .append("0").toString();    

        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(String.valueOf(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) {    

        byte[] abyte0;    

        char[] ac;    

        int i;    

        int k;    

        int j;    

        abyte0 = s.getBytes();    

        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 String.valueOf(ac);    

    }    

    public MyEclipseGen() {    

        super();    

    }    

    public static void main(String[] args) {    

        try {    

            System.out.println("please input register name:");    

            BufferedReader reader = new BufferedReader(new InputStreamReader(    

                    System.in));    

            String userId = null;    

            userId = reader.readLine();    

            MyEclipseGen myeclipsegen = new MyEclipseGen();    

            String res = myeclipsegen.getSerial(userId, "20");    // 20 0 

            System.out.println("Serial:" + res);    

            reader.readLine();    

        } catch (IOException ex) {    

        }    

    }    

}