Algortima Chipper dalam java

import java.util.LinkedHashSet;
import java.util.Set;

public class Chiper {
  //baris alphabet acuan
  private  String  alp  =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuv
wxyz0123456789 .,?!@()-_=+";//,./';[]!@#$%^&*()_+-=<>?\"{}`~\\ 
  //key  bawaan  aplikasi,  digunakan  di  inisialisasi  jika  key  yang digunakan bukan bawaan aplikasi
  private String key = "<oGHsoienJGDdop90?>";
  //panjang alphabet, digunakan untuk penggeseran dan modulus alphabet
  private int alen = this.alp.length();
  
  //constructor umum
  public Chiper(){
    this.adjustKeyWord();
  }
  
  public Chiper(String phone){
    if(!phone.equals(""))
      this.key = this.mixKeyword(phone);
    
    this.adjustKeyWord();
  }
  
  //constructor dengan keyword custom
  public Chiper(String phone,String keyword){
    if(!phone.equals(""))
      this.key = this.mixKeyword(phone);
    
    if(!keyword.equals(""))
      this.key = this.mixKeyword(keyword);
    
    this.adjustKeyWord();
  }
  
  //constructor dengan baris abjad custom dan keyword custom
  public Chiper(String phone,String keyword,String alphabet){
    this.alp = alphabet;
    this.alen = this.alp.length();
    
    if(!phone.equals(""))
      this.key = this.mixKeyword(phone);
    
    if(!keyword.equals(""))
      this.key = this.mixKeyword(keyword);
    
    this.adjustKeyWord();
  }
  //fungsi mixing 2 string keyword
  private String mixKeyword(String keyword) {
    String rkey = "";
    
    int lbk = this.key.length();
    int lik = keyword.length();
    
    int tnk = lbk>lik ? lbk : lik ;
    
    for(int i = 0;i<tnk;i++){
      if(i<lbk)
        rkey += this.key.charAt(i);
      if(i<lik)
        rkey += keyword.charAt(i);
    }
    
    return rkey;
    
  }
  
  private void adjustKeyWord(){
    this.key = adjustKeyWord(this.key);
  }
  
  //fungsi adjustment key memastikan 1 buah char/g ad yg sama
  private String adjustKeyWord(String keyword) {
    String kw = "";
    Set<Character>  keyChars  =  new
LinkedHashSet<Character>(keyword.length());
    for(char c : keyword.toCharArray()){
      if((alp.indexOf(c)  !=  -1)  &&
keyChars.add(c)){
        kw += String.valueOf(c);
      }
    }
    //Log.i("keyword",kw);
    
    return kw;

  }
  
  //fungsi fibonanci key
  private void getFibonanciKey(int llen,int klen,String line){
    //selisih panjang kalimat dengan panjang key
    int loss = llen - klen;
    //Log.i("loss",String.valueOf(loss));
    //rumus fibonanci
    int mt = 1;
    for (char c : this.key.toCharArray()){
      mt += this.alp.indexOf(c);
    }
    mt %= klen;
    //Log.i("loss",String.valueOf(mt));
    //END rumus fibonanci
    String temkey = this.key;
    while(temkey.length()<llen){
      temkey += this.key;
    }
    //Log.i("repeater",temkey);
    
    String holder = "";
    int tmp2;
    for(int i=0;i<loss;i++){
      
      tmp2  =  this.alp.indexOf(temkey.charAt(i))  + this.alp.indexOf(temkey.charAt(i+mt));
      tmp2 += this.alen;
      tmp2 %= this.alen;
      holder += this.alp.charAt(tmp2);
    }
    
    this.key = mixKeyword(holder);
    //Log.i("keywordFibo",this.key);
    //return this.key;
  }