java - LZW decoding miss the first code entry -

i followed rosetta java code implementation.

i tried lzw coding own dictionary , not ascii dictionary used. when try own dictioanry there problem decoding... result wrong, because each of decoded word don't view first 'a' letter. result have 'abraca abrac abra' , not 'braca brac bra'

i see problem in decode() method @ string act = "" + (char)(int)compressed.remove(0); remove first 'a' letter. don't have ideas how can modify line... example if use string act = "";instead of above line... coding wrong, or use command... don't know how can solve little problem... or maybe looking on bad way solution.

public class lzw {     public static list<integer> encode(string uncompressed) {      map<string,integer> dictionary = dictionaryinitstringint();             int dictsize = dictionary.size();      string act = "";     list<integer> result = new arraylist<integer>();      (char c : uncompressed.tochararray()) {         string next = act + c;         if (dictionary.containskey(next))             act = next;         else {             result.add(dictionary.get(act));             // add next dictionary.             dictionary.put(next, dictsize++);             act = "" + c;         }     }      // output code act.     if (!act.equals(""))         result.add(dictionary.get(act));     return result; }   public static string decode(list<integer> compressed) {      map<integer,string> dictionary = dictionaryinitintstring();             int dictsize = dictionary.size();      string act = "" + (char)(int)compressed.remove(0);     //string act = "";     string result = act;      (int k : compressed) {                     string entry;         if (dictionary.containskey(k))             entry = dictionary.get(k);         else if (k == dictsize)             entry = act + act.charat(0);         else             throw new illegalargumentexception("nincs ilyen kulcs: " + k);          result += entry;          dictionary.put(dictsize++, act + entry.charat(0));          act = entry;     }     return result; }  public static map<string,integer> dictionaryinitstringint() {                    char[] characters = {'a','b','c','d','e','f','g','h','i','j', 'k','l','m','n',                     'o','p','q','r','s','t','u','v','w','x','y','z',' ','!',                     '?','.',','};     int characterslength = characters.length;      map<string,integer> dictionary = new hashmap<string,integer>();      (int = 0; < characterslength; i++)             dictionary.put("" + characters[i], i);       return dictionary; }  public static map<integer,string> dictionaryinitintstring() {                    char[] characters = {'a','b','c','d','e','f','g','h','i','j', 'k','l','m','n',                     'o','p','q','r','s','t','u','v','w','x','y','z',' ','!',                     '?','.',','};     int characterslength = characters.length;      map<integer,string> dictionary = new hashmap<integer,string>();      (int = 0; < characterslength; i++)             dictionary.put(i,"" + characters[i]);       return dictionary; }  public static void main(string[] args) {      list<integer> compressed = encode("abraca abrac abra");     system.out.println(compressed);      string decodeed = decode(compressed);     // decodeed 'braca brac bra'     system.out.println(decodeed); } 

}

the rosetta example use

"" + (char) (int) compressed.remove(0); 

because first 256 entries of dictionnary map 'char' values.

with custom dictionnary line should be:

string act = dictionary.get(compressed.remove(0));