Decompress.java

Decompress.java

contents ::

  App.java
  BitStreamInputStream.java
  BitStreamOutputStream.java
  Compress.java
  Decompress.java
  lzwScript
  input
  Makefile

package zzhao_ex9;
import java.util.*;
import java.io.*;

public class Decompress{
    public static void main(String[] args){
         Decompress tester=new Decompress();
         String inputfilename = "";
         String outputfilename = "";

             if (args.length == 1){//ARGS="test"
                  inputfilename = args[0];
             }//else{System.out.println(args.length);
             //BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
             //inputfilename ="test";
             //PrintWriter output = new PrintWriter(new FileWriter(new File(inputfilename)));
             //String str="";
             //while((str=input.readLine())!=null){
             //output.print(str);
             //}
             // }
             outputfilename = inputfilename + ".DEC";
         try{
             tester.decompress(inputfilename, outputfilename);

         }catch(IOException e){
             System.out.println("Error: " + e);
             System.exit(1);
         }


    }//main

    public void decompress(String inputfilename, String outputfilename)throws IOException{

         Vector string_table = new Vector();
         int MAX_SIZE=4000;
         for(int i=0; i<256; i++)
             string_table.add(String.valueOf((char)i));

         int oldCode=0, newCode=0;
         try{

             BufferedInputStream inBuf = new BufferedInputStream(new FileInputStream(inputfilename));
             BitStreamInputStream breader = new BitStreamInputStream(inBuf, 12);
             BufferedOutputStream bwriter = new BufferedOutputStream(new FileOutputStream(outputfilename));

             String aString = "", aChar = "";

             oldCode = (int)breader.readBitField();
             aChar=String.valueOf((char)oldCode);
             bwriter.write(oldCode);
             while((newCode = (int)breader.readBitField())!=-1){

                  if(newCode >= string_table.size()){
                      aString =(String)string_table.get(oldCode);
                      aString = aString + aChar;
                  }else{
                      aString = (String)string_table.get(newCode);
                  }

                  bwriter.write(aString.getBytes());
                  aChar = aString.substring(0, 1);
                  string_table.add((String)string_table.get(oldCode) + aChar);
                  oldCode = newCode;
             }// end while

             if(string_table.size()>MAX_SIZE){
                  string_table.removeAllElements();
                  for(int j=0; j<256; j++)
                      string_table.add(String.valueOf((char)j));
             }

             bwriter.close();
             breader.close();
         }catch(IOException e){System.out.println("Error: " + e);}

         //if(string_table.size()>MAX_SIZE){
         //string_table.removeAllElements();
         //for(int j=0; j<256; j++)
         //string_table.add(String.valueOf((char)j));
         //}
         //for testing only-table ok
         //for(int i=0; i<string_table.size(); i++)
         //if(i>255)
         //System.out.println(" in hashtable:  " +
         // + i + "    " + (String)string_table.elementAt(i));
    }// decompress
}

James Little