String to bytes to string

Question

The question is in comments in the code, I thought that'd be an easier way to ask...

Easy question, but I can't seem to find an answer. I want to convert a String to it's byte[] (easy, String.getBytes()). Then I want to convert a String of bytes (101011010101001 for example) to a byte[] and get the String value of that (that's easy too: new String(byte[]))

Here's what I've got so far:

Scanner scan = new Scanner(System.in);
String string = scan.nextLine();
String byteString = "";
for (byte b : string.getBytes()) {
  byteString += b;
}
System.out.println(byteString);

//This isn't exactly how it works, these two parts in separate methods, but you get the idea...

String byteString = scan.nextLine();
byte[] bytes = byteString.literalToBytes() //<== or something like that...
//The line above is pretty much all I need...
String string = new String(bytes);
System.out.println(string);

Check this one http://stackoverflow.com/questions/2057387/converting-a-set-of-strings-to-a-byte-array — StepTNT, May 23 '12 at 14:27
I'll edit it so it's a little more clear, but if you see in the code I have commments — kentcdodds, May 23 '12 at 14:27
First of all I would suggest you to use a StringBUilder for the variable byteString and then convert it back to string after the loop. Little Optimization :) — dharam, May 23 '12 at 14:31
@StepTNT, that led me to the right answer. If you want to formalize the answer I'll accept it. Thanks. — kentcdodds, May 23 '12 at 14:33
I see that you added your own solution, you can accept that one :) — StepTNT, May 23 '12 at 15:05
@StepTNT I tried to give you as much credit as I could. If you'd like I can remove mine and you can add one so you get the credit. Either way, thanks a lot. — kentcdodds, May 23 '12 at 15:15
There's no need for that. Just accept yours, I just gave you a link, no answer at all :) — StepTNT, May 23 '12 at 15:36

score 1 · Answer 1 · edited May 23 '17 at 11:56

1

EDIT

Please see this answer for a solution.

With this you can:

String string = scan.nextLine();
String convertByte = convertByte(string.getBytes());
System.out.println(convertByte);
String byteString = scan.nextLine();
System.out.println(new String(convertStr(byteString)));

edited May 23 '17 at 11:56

Community

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answered May 23 '12 at 14:30

morja

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Sorry, that wont work for the cases I'm working with. I just tried it with the string `kent` which gave me a byte string of: `107101110116`. Giving your answer that byte string throws a NumberFormatException on `Integer.toBinaryString(Integer.parseInt(string));` Which makes sense. But one of the commenters on my question gave me a link to a good answer. If they doesn't post the comment in an answer I'll just post my answer. Thanks for the help though. – kentcdodds May 23 '12 at 14:47
I dont just want to copy the solution, but I added a link to it. – morja May 23 '12 at 14:56

score 1 · Answer 2 · answered May 23 '12 at 14:31

1

This won't work. The problem is that when you convert your bytes to a string you are going to get a string like

2532611134

So analyzing this string, is the first byte 2, or 25, or 253?

The only way to make this work would be to use a DecimalFormat and make sure every byte is 3 characters long in your string

answered May 23 '12 at 14:31

ControlAltDel

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Another option would be to convert to hexadecimal (2 digits 0-F per byte) or use a separator between the bytes, e.g. space character. – user1252434 May 23 '12 at 15:13

score 1 · Accepted Answer · edited May 23 '17 at 12:28

Alright, because the commenter who pointed me to this question (which lead me to this answer) isn't going to answer, I'll just post the solution here:

Scanner scan = new Scanner(System.in);
String pass = scan.nextLine();
StringBuilder byteString = new StringBuilder();
for (byte b : pass.getBytes()) {
  b = (byte) (b);
  byteString.append(b).append(","); //appending that comma is what does the trick.
}
System.out.println(byteString);
//
String[] split = byteString.toString().split(","); //splitting by that comma is what does the trick... too...
byte[] bytes = new byte[split.length];
for (int i = 0; i < split.length; i++) {
  bytes[i] = (byte) (Byte.valueOf(split[i]).byteValue());
}
System.out.println(new String(bytes));

dharam · Answer 4 · 2012-05-23T14:52:12.407

0

I guess what you want is this

// to get back the string from byte array
StringBuilder byteString = new StringBuilder();
for (byte b : string.getBytes()) {
    byteString.append((char)b);
}
   System.out.println(byteString.toString());
// to get the binary representation from string
StringBuilder byteString = new StringBuilder();
    for (byte b : string.getBytes()) {
        System.out.print(Integer.toBinaryString((int)b));
    }
        System.out.println(byteString.toString());

edited May 23 '12 at 14:52

answered May 23 '12 at 14:46

dharam

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That is the same as new String(string.getBytes()). It does not print the binary representation of the String. – morja May 23 '12 at 14:49
@morja, that's right. I need it to print the byte representation and then convert the string version of the byte representation back to the string it represented originally. Someone answered the question in a comment though. I'm just waiting for a formalized answer so I can accept it. – kentcdodds May 23 '12 at 14:50
Awesome, now to answer the *original* question. How to convert that byte string back to the original string it represents? I already got the answer, but feel free to update your answer if you like. – kentcdodds May 23 '12 at 14:55
You have to substring the byteString into pieces of length 8 and individually parse each of them into int and then typecaste into a byte and then typecaset to char. – dharam May 23 '12 at 15:12

String to bytes to string

4 Answers4