converting a string to binary using UTF-8 encoding

Question

I have to convert a string into binary using UTF-8, but i am unable to do that. I have tried

String encodedName=URLEncoder.encode(name, "UTF-8");

but it doesn't gave me the binary format, it just returned me the same string with slight changes, please help.

EDIT:

what i have to do: I have a string suppose "HelloWorld" I have to convert it to binary using "UTF-8" and then use SHA1 hashing algorithm and from this i will get the hashkey and this is what i need "a hashkey".

I found this one for SHA1 hashing.

   public class AeSimpleSHA1 { 

    private  String convertToHex(byte[] data) { 
        StringBuffer buf = new StringBuffer();
        for (int i = 0; i < data.length; i++) { 
            int halfbyte = (data[i] >>> 4) & 0x0F;
            int two_halfs = 0;
            do { 
                if ((0 <= halfbyte) && (halfbyte <= 9)) 
                    buf.append((char) ('0' + halfbyte));
                else 
                    buf.append((char) ('a' + (halfbyte - 10)));
                halfbyte = data[i] & 0x0F;
            } while(two_halfs++ < 1);
        } 
        return buf.toString();
    } 

    public  String SHA1(String text) 
    throws NoSuchAlgorithmException, UnsupportedEncodingException  { 
    MessageDigest md;
    md = MessageDigest.getInstance("SHA-1");
    byte[] sha1hash = new byte[40];
    md.update(text.getBytes("iso-8859-1"), 0, text.length());
    sha1hash = md.digest();
    return convertToHex(sha1hash);

    } 

}

Jon Skeet · Accepted Answer · 2012-02-21 08:22:30Z

2

It's not really clear what you mean, but you'd usually use:

byte[] data = name.getBytes("UTF-8");

I'm not sure why you've used URLEncoder in your attempt - or what your "desired result" is.

EDIT: Converting the binary data back to text so you can then call getBytes() on it in your SHA1 method makes no sense. Just change your hashing method do:

public String hashSha1(byte[] data) throws NoSuchAlgorithmException, 
    UnsupportedEncodingException { 
  MessageDigest md = MessageDigest.getInstance("SHA-1");
  md.update(data, 0, data.length);
  return convertToHex(md.digest());
}

edited Feb 21, 2012 at 8:22

answered Feb 21, 2012 at 7:00

Jon Skeet

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5 Comments

droid Over a year ago

I was not getting that in binary format, that is what was my desired result.Your code is really helpful, I got the encoded format in data but i have to store it as a string, can you please help me on that.

Jon Skeet Over a year ago

@user1211188: It's entirely unclear what you're trying to achieve. byte[] is binary data, String is text data. Please clarify what you're after - read tinyurl.com/so-hints and edit your question.

droid Over a year ago

OK, lets make it clear i converted the string to binary using UTF-8, now what i got is stored in data.Now, i have to use SHA1 Hashing algorithm and hence for that i need this byte[] data to be a string, so that i can give it as a input for another encoding.

Jon Skeet Over a year ago

@user1211188: No, the input for SHA-1 should be a byte[], not a String. You should really edit your question to give us the whole picture about what you're trying to do.

Jon Skeet Over a year ago

@user1211188: You're converting the input text into binary to hash it - don't do that. Just pass in the binary data. Will edit my answer...

waqaslam · Accepted Answer · 2012-02-21 07:01:41Z

0

why dont you simply use string's getBytes() method to convert into UTF-8 bytes array? see below:

String s = "this is my string";
byte[] bytes = s.getBytes();   // default:  UTF-8

the default encoding is UTF-8 in android, though you may further define your own encoding in the same method

answered Feb 21, 2012 at 7:01

waqaslam

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3 Comments

Jon Skeet Over a year ago

Even though I believe UTF-8 is the default encoding on Android, I still think it makes sense to be explicit about it.

TomeeNS Over a year ago

@Jon Skeet: If so, then being explicit (as if you had to care for it all the time) acts against the meaning of default UTF-8 and the whole Android programming principles ("Simplify My Life").

Jon Skeet Over a year ago

@TomeeNS: I think we'll have to agree to disagree on this.

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