App.java

App.java

contents ::

  App.java
  BitStreamInputStream.java
  BitStreamOutputStream.java
  lzwScript
  input

/* James Little 5-5-01
   I hope this is one of the last programs I have to write in this course.
*/

package jlittle_ex9;

import java.io.*;
import java.util.*;

public class App {
    private static App a;
    private static BitStreamInputStream reader;
    private static BitStreamOutputStream writer;
    private static String outFile;

    public static void main(String [] args){
         String inFile = null;
         System.out.println("input file is now input");
         inFile = "BitStreamInputStream.java";
         outFile = inFile+".LZW";

         try{
             reader = new BitStreamInputStream(new FileInputStream(inFile));
             writer = new BitStreamOutputStream(new BufferedOutputStream(new FileOutputStream(outFile)), 12);
         } catch (FileNotFoundException e) {
             System.out.println("flying pigs in space!!!!!!!!!! "+e);
         }

         a = new App();
         a.compress();
         a.decompress();
    }

    // compression routine
    public void compress(){

         int MAX_VALUE = 4000;
         Vector string_table = new Vector();

         for(int i=0; i<256; i++){
             string_table.add(String.valueOf((char)i));
         }

         System.out.println("I am now compressing...");
         int next_code = 256, intStr = 0, intChar=0;

         try{
             intStr = reader.read();
             String aString = String.valueOf((char)intStr);
             String nextChar = "";
             int i = 0;

             while((intChar = reader.read())!=-1){

                  nextChar = String.valueOf((char)intChar);
                  if(string_table.contains(aString + nextChar)){
                      aString = aString + nextChar;
                  }else{
                      i = string_table.indexOf(aString);
                      writer.writeBitField(i);
                      string_table.add(aString + nextChar);
                      aString = nextChar;
                  } // end if
                  if(string_table.size()>MAX_VALUE){
                      string_table.removeAllElements();
                      for(int j=0; j<256; j++){
                           string_table.add(String.valueOf((char)j));
                      }
                  }
             } // end while

             i = string_table.indexOf(aString);
             writer.writeBitField(i); // write a string
             writer.close();
             reader.close();
         } catch(IOException e){
             System.out.println("ERROR: " + e);
         }

         //for(int j=256; j<string_table.size() ; j++){
         System.out.println("\t"+string_table.size());
         //}


    } // end compress

    // decompression routine
    public void decompress(){
         int MAX_VALUE = 4000;
         // once we get to here we are going
         // to have to flush the table

         try{
             reader = new BitStreamInputStream(new BufferedInputStream(new FileInputStream(outFile)), 12);
             writer = new BitStreamOutputStream(new FileOutputStream(outFile+".DEC"));
         } catch (FileNotFoundException e) {
             System.out.println("flying pigs in space!!!!!!!!!!"+e);
         }

         Vector string_table = new Vector();

         for(int i=0; i<256; i++){
             string_table.add(String.valueOf((char)i));
         }

         System.out.println("I am now expanding...");
         int oldCode = 0, newCode = 0;

         try{

             String aString = "", aChar = "";

             oldCode = (int)reader.readBitField();
             aChar = String.valueOf((char)oldCode);

             writer.write(oldCode);  // looks like it should be aChar.. but done with oldCode??

             // loop through the rest of the characters
             while((newCode=(int)reader.readBitField())!=-1) {

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

                  //System.out.print(aString.getBytes());
                  writer.write(aString.getBytes());
                  aChar = aString.substring(0,1);
                  string_table.add((String)string_table.get(oldCode)+aChar);
                  oldCode = newCode;

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

             } // end while
             reader.close();
         } catch(IOException e){
             System.out.println("ERROR: " + e);
         }

         //for(int j=256; j<string_table.size() ; j++){
         //  System.out.println(j+"\t"+string_table.elementAt(j));
         //}

    }// end decompress

} // end App

James Little