CODEWITHSUNDEEP
javastringbyte
Jay
Jay

Reputation: 281

Converting a specific string to byte[]

I'm trying to convert specific String to a byte[].

The String looks like: 55 55 F5 FF FF

and here is the method I wrote for it, hope someone can tell me what is wrong or has a better solution. 

public static byte[] stringToByte(String text) {
    //byte[] length ==> String (length+1)/3
    byte raw[] = new byte[(text.length() + 1) / 3];
    int j = 0;
    for (int i = 0; i < text.length(); i += 2) {
        String h = "";
        h += text.charAt(i);
        h += text.charAt(i + 1);
        i++;
        raw[j] = Byte.valueOf(h);
        j++;
    }
    return raw;
}

The problem is it works until it comes to F5.

I need the same values in the byte[] as if I use

byte raw[] = {(byte) 0x55, (byte) 0x55, (byte) 0x5F,(byte) 0xFF,(byte) 0xFF};

Upvotes: 1

Views: 2393

Answers (4)

Paul Vargas
Paul Vargas

Reputation: 42020

You could also use StringTokenizer for each token.

public static byte[] stringToByte(String text) {
    StringTokenizer st = new StringTokenizer(text);
    byte raw[] = new byte[st.countTokens()];
    for (int i = 0; i < raw.length; i++) {
        raw[i] = (byte) Integer.parseInt(st.nextToken(), 16);
    }
    return raw;
}

Upvotes: 0

Marko Topolnik
Marko Topolnik

Reputation: 200148

This will work:

public static byte[] stringToByte(String text) {
  final String[] split = text.split("\\s+");
  final byte[] result = new byte[split.length];
  int i = 0;
  for (String b : split) result[i++] = (byte)Integer.parseInt(b, 16);
  return result;
}

Why? byte is a signed quantity and you cannot parse anything out of its range directly into byte. But if you parse an int and then use a narrowing conversion into byte, you'll get your result.

Upvotes: 2

user845279
user845279

Reputation: 2804

byte[] raw = new byte[text.length() >> 1];
for(int i=0; i<text.length();i+=2){
    raw[i >> 1] = Integer.parseInt(text.substring(i, i+2),16);
}

I used Integer.parseInt() instead of Byte.parseByte() because Byte is not unsigned byte. I tried it with String text = "55555FFF";.

Upvotes: 0

Jon7
Jon7

Reputation: 7215

It looks like you're just looping through a space delimited String and parsing out Byte objects. In the case, I'd suggest using something like:

         String text = "";
         String[] strArr = text.split(" ");
         for (String str: strArr)
         {
             //convert string to byte here
         }

Upvotes: 0

Related Questions