Binary data corruption using Buffered(Reader|Writer)

import java.io.File;
import java.io.FileWriter;
import java.io.FileReader;
import java.io.BufferedWriter;
import java.io.BufferedReader;
import java.io.IOException;

class jtest
{
    public static void main(String[] argz)
    {
        try
        {
            File f1 = new File("bintest1");
            File f2 = new File("bintest2");
            if(!f1.exists()) f1.createNewFile();
            if(!f2.exists()) f2.createNewFile();

            BufferedWriter bw = new BufferedWriter(new FileWriter(f1.getAbsoluteFile()));
            for(int i = 0; i != 256; i++)
            {
                bw.write(String.valueOf((char)i));
            }
            bw.close();

            BufferedReader br = new BufferedReader(new FileReader(f1.getAbsoluteFile()));
            bw = new BufferedWriter(new FileWriter(f2.getAbsoluteFile()));
            StringBuilder result = new StringBuilder("");
            String line = br.readLine();
            while (line != null)
            {
              result.append(line);
              line = br.readLine();
              if (line != null) {
                result.append("\n");
              }
            }
            br.close();

            String str = result.toString();

            for(int i = 0; i != str.length(); i++)
            {
                bw.write(String.format("%02x", (int)str.charAt(i)));
                bw.newLine();
            }

            bw.close();

        }
        catch(IOException ioex)
        {
            ioex.printStackTrace();
        }
    }
}