problems reading 2d byte array from a text file

Question

I'm having problems reading a byte array back from a text file that I had already written the byte array to.

Here is the code for writing the byte array to the file

    FileOutputStream fout = new FileOutputStream(new File("C:\\Users\\lvannini\\Desktop\\FileSystem\\diskFiles\\", fileName));
    for(int i = 0; i < 64; ++i){
        for(int j = 0; j < 64; ++j)
            fout.write(String.valueOf(ldisk[i][j]).getBytes());
        fout.write(System.lineSeparator().getBytes()); //write line break;

As far as I'm aware, this part is working correctly, because my output text file contains the appropriate contents of the 2d array I am using. An example of the first 9 lines of the text file are printed as follows:

00-1-16000000000000000000000000000000000000000000000000000000000000
00024000700000000000000090000000000071000100001100000000000800000000
-1-1-1-1000000000000-1-1-1-1000000000000-1-1-1-1000000000000-1-1-1-1000000000000
-1-1-1-1000000000000-1-1-1-1000000000000-1-1-1-1000000000000-1-1-1-1000000000000
-1-1-1-1000000000000-1-1-1-1000000000000-1-1-1-1000000000000-1-1-1-1000000000000
-1-1-1-1000000000000-1-1-1-1000000000000-1-1-1-1000000000000-1-1-1-1000000000000
-1-1-1-1000000000000-1-1-1-1000000000000-1-1-1-1000000000000-1-1-1-1000000000000
10010010000001979899000021021111110000900000000000000010000000000000000800000000
0000000000000000000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000000000000000000000000000

However, using this following code to read back from the file into the 2D array:

FileInputStream fin = new FileInputStream("C:\\Users\\lvannini\\Desktop\\FileSystem\\diskFiles\\" + fileName);
    for(int i = 0; i < 64; ++i)
        fin.read(ldisk[i]);

    fin.close();

gives me the actual ASCII values of each byte being read in. For instance, after reading in the first line of the text file, my 2d array, ldisk[0], contains:

48 48 45 49 45 49 54 48 48 48 . . .

Where am I losing the translation from the byte values to the ascii values? I'm suspecting I'm saving the byte values to the text file incorrectly. Any advice/responses are very much appreciated! Thanks again.

Answer 1

Where am I losing the translation from the byte values to the ASCII values?

FileInputStream.read() is giving you the ASCII code for the byte. See ASCII table , which reveals you're not losing the translation.

Just cast that ASCII code to a character code:

char c = (char)fin.read(ldisk[i]);

OR subtract 48 from it to get the integer value:

-48 + fin.read(ldisk[i])

You still have to deal with the minus signs taking up bytes, so your

for(int i = 0; i < 64; ++i)

is inadequate with 64 as limit when there are minus signs in the file.

Answer 2

Your problem is with FileInputStream. There are many ways get ASCII values of each byte being read but the easiest is probably BufferedReader with defined charset.

Charset charset = Charset.forName("US-ASCII");
BufferedReader in = Files.newBufferedReader(C:\\Users\\lvannini\\Desktop\\FileSystem\\diskFiles\\" + fileName, charset);

String line;
while((line = in.readLine()) != null)
{
   //do something with your input
}
in.close();