Unable to convert binary file properly

Question

I have to read a file called test.p2b with the following content:

I tried reading it like this:

static void branjeIzDatoteke(String location){
    byte[] allBytes = new byte[10000];
    try {
        InputStream input = new FileInputStream(location);
        int byteRead;
        int j=0;
        while ((byteRead = input.read())!=-1){
            allBytes[j] = (byte)input.read();
        }
        String str = new String(allBytes,"UTF-8");

        for (int i=0;i<=str.length()-8;i+=8){
            //int charCode = Integer.parseInt(str.substring(i,i+8),2);
            //System.out.println((char)charCode);

            int drek = (int)str.charAt(i);
            System.out.println(Integer.toBinaryString(drek));
        }
    } catch (IOException ex) {
        Logger.getLogger(Slika.class.getName()).log(Level.SEVERE, null, ex);
    }

}

I tried just printing out the string (when I created String str = new String(allBytes,"UTF-8");), but all I get is a square at the beginning and then 70+ blank lines with no text. Then I tried the int charCode = Integer.parseInt(str.substring(i,i+8),2); and printing out each individual character, but then I got a NumberFormatException. I even tried just converting Finally I tried the Integer.toBinaryString I have at the end but in this case I get 1s and 0s. That's not what I want, I need to read the actual text but no method seems to work. I've actually read a binary file before using the method I already tried: int charCode = Integer.parseInt(str.substring(i,i+8),2); System.out.println((char)charCode); but like I said, I get a NumberFormatException. I don't understand why these methods won't work.

you have multiple flaws. Firstly in your while you're calling `input.read()` twice. The second time just assign `byteRead` to the array. Secondly you'er not incrementing the variable `j` inside the while, do that by replacing `allBytes[j]` with `allBytes[j++]` — Lino, Jun 01 '18 at 08:39
`String` is not a container for binary data. Don't post pictures of text here. Post the text. — user207421, Jun 01 '18 at 09:58

Karol Dowbecki · Accepted Answer · 2018-06-01T13:50:17.733

1

If you want to read all the bytes you can use the java.nio.file.Files utility class:

Path path = Paths.get("test.p2b");
byte[] allBytes = Files.readAllBytes(path);
String str = new String(allBytes, "UTF-8");
System.out.print(str);

You iteration over str content might not work. Certain UTF characters are expressed as surrogate pairs, a code points that can span more than one char (as explained here). Since you are using UTF you should be using String#codePoinst() method to iterate over the code points instead of the characters.

edited Jun 01 '18 at 13:50

answered Jun 01 '18 at 09:38

Karol Dowbecki

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Sorry for deleting my comment. I just noticed that you mentioned I should the String.codePoint() (or rather codePoints) method to iterate through the data. I tried using the method like this: IntStream text = String.codePoints(); but I get an error saying "Non-static method cannot be referenced from a static context" because I'm writing a static method of a certain class. Do I absolutely have to change this or is there any way I can still implement this? – Sebastjan Jun 01 '18 at 13:49
call the method on an instance of a string e.g. `str.codePoints().forEach(System.out::println)`. It's **not** a static method of `String` class. – Karol Dowbecki Jun 01 '18 at 13:52

Unable to convert binary file properly

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