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Expertise: Intermediate
Language: Java

November 5, 1999

Hex Your Bytes to Display

Editor's Note:This text has changed from the original version.

Have you ever needed to convert a byte array (byte []) into a displayable hex string? The JDK does not provide this capability for byte arrays, only for the wrapper classes.

Below is the code which will convert a byte array into a displayable "hex" representation of the string.

Now you can turn

 
byte b[] = {0xf1, 0x0d,
  0x3c, 0x44};

into:

 String s =
  "F10D3C44"

like this:

 String s =
  byteArrayToHexString(b);

• provides the same functionality found in Integer.toHexString(), Short.toHexString(), etc...
• Simple to use
• Fast, efficient and accurate
• Tested and proven

Here's the code:

 /**

* Convert a byte[] array to readable string format. This makes the "hex"
readable!

* @return result String buffer in String format 

* @param in byte[] buffer to convert to string format

*/

static String byteArrayToHexString(byte in[]) {

    byte ch = 0x00;

    int i = 0; 

    if (in == null || in.length <= 0)

        return null;

        

    String pseudo[] = {"0", "1", "2",
"3", "4", "5", "6", "7", "8",
"9", "A", "B", "C", "D", "E",
"F"};

    StringBuffer out = new StringBuffer(in.length * 2);

    

    while (i < in.length) {

        ch = (byte) (in[i] & 0xF0); // Strip off
high nibble

        ch = (byte) (ch >>> 4);
     // shift the bits down

        ch = (byte) (ch & 0x0F);    
// must do this is high order bit is on!

        out.append(pseudo[ (int) ch]); // convert the
nibble to a String Character

        ch = (byte) (in[i] & 0x0F); // Strip off
low nibble 

        out.append(pseudo[ (int) ch]); // convert the
nibble to a String Character

        i++;

    }

    String rslt = new String(out);

    return rslt;

}    

Stay tuned, I'll present some additional routines which take the "hex" data and format it into a "Hex Dump" format like: 0000: 32 00 00 00 00 49 99 04 13 14 56 20 17 55 2B 3F ____[2 I™V U+?]
0010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ____[ ]
0020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ____[ ]
The above example was created using byteArrayToHexString() along with another routine....I also have a hex dump routine which dumps the hex data in "old" mainframe EBCDIC style format where each byte is display one nibble on top of the other.