java - Huffman Decompression -

i have been working on huffman compression , decompression program. @ stage, compression program works fine, can't seem make decompression code reproduce original file compressed. guess doing wrong. complete code below. please appreciated.

import java.io.*; import java.util.*;  public class huffmain {     public static priorityqueue<node> q;     public static hashmap<character, string> chartocode;     public static hashmap<string, character> codetochar;      @suppresswarnings("resource")     public static void main(string[] args) throws filenotfoundexception {         // read contents of file         string text = new scanner(new file("text.txt")).usedelimiter("\\a").next();          // count frequency of characters         hashmap<character, integer> dict = new hashmap<character, integer>();         for(int = 0; < text.length(); i++) {             char = text.charat(i);             if(dict.containskey(a))                 dict.put(a, dict.get(a)+1);             else                 dict.put(a, 1);         }          // create forest (group of trees) adding nodes priority queue         q = new priorityqueue<node>(100, new frequencycomparator());         int n = 0;         for(character c : dict.keyset()) {             q.add(new node(c, dict.get(c)));             n++;         }         node root = huffmain(n);         buildtable(root);          string compressed = compress(text);         savetofile(compressed);          string decompressed = decompress(compressed);         writetofile(decompressed);     }      // method builds tree based on frequency of every characters      public static node huffmain(int n) {         node x, y;         for(int = 1; <= n-1; i++) {             node z = new node();             z.left = x = q.poll();             z.right = y = q.poll();             z.freq = x.freq + y.freq;             q.add(z);         }         return q.poll();     }      // method builds table compression , decompression     public static void buildtable(node root) {         chartocode = new hashmap<character, string>();         codetochar = new hashmap<string, character>();         postorder(root, new string());     }      // method used traverse root-to-leaves     public static void postorder(node n, string s) {         if(n == null)             return;         postorder(n.left, s+"0");         postorder(n.right, s+"1");          // visit nodes keys         if (!character.tostring(n.alpha).equals("&#092;&#048;")){             system.out.println("{" + n.alpha + ":" + s + "}");             chartocode.put(n.alpha, s);             codetochar.put(s, n.alpha);         }     }      //assuming tree , dictionary built...     public static string compress(string s) {         string c = new string();         for(int = 0; < s.length(); i++)             c = c + chartocode.get(s.charat(i));         return c;     }      //assuming tree , dictionary built...     public static string decompress(string s) {         string temp = new string();         string result = new string();         for(int = 0; < s.length(); i++) {             temp = temp + s.charat(i);             if(codetochar.containskey(temp)) {                 result = result + codetochar.get(temp);                 temp = new string();             }         }         return result;     }     public static void savetofile(string l) throws filenotfoundexception {         printwriter ofile = new printwriter("text.txt.huf");         ofile.print(chartocode.size());         for(char s : chartocode.keyset())             ofile.println("{" +s + ":" + chartocode.get(s)+ "}");         ofile.println(l);         ofile.close();     }      public static void writetofile(string i) throws filenotfoundexception {         printwriter ifile = new printwriter("note.txt");         ifile.print(codetochar.size());         (string s : codetochar.keyset())             ifile.println("{" +s + ":" + codetochar.get(s)+ "}");         ifile.println(i);         ifile.close();     } } //creating node class     class node {     public char alpha;     public int freq;     public node left, right;      public node(char a, int f) {         alpha = a;         freq = f;     }       public node() {     }      public string tostring() {         return alpha + " " + freq;     }     }      class frequencycomparator implements comparator<node> {     public int compare(node a, node b) {         int freqa = a.freq;         int freqb = b.freq;         return freqa-freqb;     }  } 

the problem storing in codetochar character 0 values unusable codes, codetochar.containskey(temp) condition in decompress method returns true codes.

if added && codetochar.get(temp)!=0 condition work fine.

the method be:

public static string decompress(string s) {     string temp = new string();     string result = new string();     for(int = 0; < s.length(); i++) {         temp = temp + s.charat(i);         character c = codetochar.get(temp);         if(c!=null && c!=0) {             result = result + c;             temp = "";         }     }     return result; } 

tested text "lorem ipsum" compressed "1010111011111011000101101100011110000" , decompressed fine.