[Norm]

I reworked tim's code to use some of the built in methods. Probably not as efficient but is some shorter. Also for testing I prefer to have all the data in the program vs external files, so I used ByteArrays in place of files.

Code:

/*
 * Main.java
 *
 * Created on January 15, 2008, 9:35 AM
 * Modified July 28, 2008 by Norm
 */

package stringbits;

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

/**
 *
 * @author tim
 */
public class Main {

    //--------------------------------------------------------------------------------
    public static String[] readBinaryStrings(InputStream is, int size) throws Throwable{
        boolean EOF = false;
        Vector<String> list = new Vector<String>(); // Save chunks of size bytes
        String current = "";
        do{
            int next = is.read();
            if (next != -1){   // test EOF
                String add = "00000000"+Integer.toBinaryString(next);
                add = add.substring(add.length()-8);  // get rightmost 8 chars
                current += add;
                if (current.length() >= size * 8){
                    list.add(new String(current));
                    current = "";
                }
            } else {
                if (!current.equals("")) 
                    list.add(new String(current)); // add partial string
                EOF = true;
            }
        } while (!EOF);
        is.close();

        // Convert the Vector to an String array
        return list.toArray(new String[list.size()]); // return result;
    }

    //----------------------------------------------------------------------------------
    // Convert array of String representation of binary to a single String
    public static void writeBinaryStrings(OutputStream os, String[] bitStrings) throws Throwable{
        final int ChunkSize = 8;
        for (String string : bitStrings){
            int nbrChunks = string.length() / ChunkSize;
            // Get chars in 8 char chunks
            for (int i = 0; i < nbrChunks; i++){
                int startIndex = i * ChunkSize;
                int endIndex = startIndex + ChunkSize;
                String next = string.substring(startIndex, endIndex);  // next 8 bytes
                os.write(Byte.parseByte(next, 2));  // to a byte
            } // end for(i)
        }// end for(string)
        os.close();
    }
    //-----------------------------------------------------------------------------------
    // Testing code here
    public static void main(String[] args) {
        // Define some test data
        byte[] byteData = new byte[] {0x35, 0x73, (byte)0x9A};     //0011 0101 0111 0011 1001 1010
        String inputData = "This is a string that should be long enough to show that the code works";
        byteData = inputData.getBytes();

        ByteArrayInputStream bais = new ByteArrayInputStream(byteData);
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
         
        try{
            String[] bit64Strings = readBinaryStrings(bais, 8);
            for (String string : bit64Strings){
                System.out.println(string);  // show results
            }
            // Now convert back
            writeBinaryStrings(baos, bit64Strings);
            System.out.println(baos);        // should be same as original
            // Test it equal
            System.out.println("output " + (baos.toString().equals(inputData) ? "matches"
                                           : "does NOT match" ) + " input");              
        } catch (Throwable e) {
            showError(e);
        }
    }
    public static void showError(Throwable e){
        System.out.println("Problem: " + e.getMessage());
    }
}