Getting different byte array than written to file when reading from file

Question

I'm writing my byte array to a file:

PrintWriter pw = new PrintWriter(new FileOutputStream(fileOutput, true));
pw.write(new String(cryptogram, Charset.defaultCharset()));
pw.close();

Then, I am reading it from the file like this:

String cryptogramString = new String();
while (scPriv.hasNext()) {
    linePriv = scPriv.nextLine();
    cryptogramString += linePriv;
}

But I don't know how to make byte[] from cryptogramString. I'am trying this:

byte[] b = cryptogramString.getBytes(Charset.defaultCharset());
System.out.println(Arrays.toString(b));
System.out.println(Arrays.toString(cryptogram));

But it doesn't return the same values. Does anyone have an idea how to make this right?

I don't understand _doesn't return me same values_. What are you comparing? — Savior, Apr 26 '16 at 18:21
This doesn't actually sound like something that should be interacting with strings, but rather should be just using `InputStream` and `OutputStream` and dealing strictly with bytes? — Louis Wasserman, Apr 26 '16 at 18:22
System.out.println(Arrays.toString(b)); is not the same as System.out.println(Arrays.toString(cryptogram)); — Pan Wolodyjowsky, Apr 26 '16 at 18:22
I have a file that contains xml and then plain text, so i cant read a file as a whole — Pan Wolodyjowsky, Apr 26 '16 at 18:23
`hasNext` checks for an available token, while `nextLine` reads until the next line separator, excluding the line separator characters from the return value. Just read the file into a `byte[]` directly as previously suggested. — Savior, Apr 26 '16 at 18:25

score 2 · Accepted Answer · edited May 23 '17 at 12:23

2

You should decide whether you are writing text or binary.

Encrypted data is always binary which means you shouldn't be using Reader/Writer/String classes.

try (FileOutputstream out = new FileOutputStream(filename)) {
    out.write(bytes);
}

to read back in

byte[] bytes = new byte[(int) (new File(filename).length())];
try (FileInputstream in = new FileInputStream(filename)) {
    in.read(bytes);
}

I have a file that contains xml and then plain text, so i cant read a file as a whole

You also can't write binary into a text file. You can encode it using base64.

Storing base64 data in XML?

edited May 23 '17 at 12:23

Community

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answered Apr 26 '16 at 18:23

Peter Lawrey

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I have file structure as follows ` Cryptogram` How could i read this Cryptogram with FileInputStream without reading xml? I cannot use base64 beacuse it extends the size. – Pan Wolodyjowsky Apr 26 '16 at 18:36
You are mixing text (xml) and binary data in a single file? That is really not a good way to do it. – Andreas Apr 26 '16 at 18:39
This are my requirements for this task and i have to do it this way. If it was up to me i would find different way. – Pan Wolodyjowsky Apr 26 '16 at 18:40
@SzymonKaczorowski You can add it, but it won't be XML any more. – Peter Lawrey Apr 26 '16 at 18:47
But how can i get this Cryptogram with FileInputStream? – Pan Wolodyjowsky Apr 26 '16 at 18:56
1

@SzymonKaczorowski you have to read it the same as above, but you have to skip the XML first, but no more. I suggest reading it using the binary mode as well to avoid reading too much. – Peter Lawrey Apr 26 '16 at 18:58

Getting different byte array than written to file when reading from file

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