Java code To convert byte to Hexadecimal

Question

I have an array of bytes. I want each byte String of that array to be converted to its corresponding hexadecimal values.

Is there any function in Java to convert a b

Answer 1

Just like some other answers, I recommend to use String.format() and BigInteger. But to interpret the byte array as big-endian binary representation instead of two's-complement binary representation (with signum and incomplete use of possible hex values range) use BigInteger(int signum, byte[] magnitude), not BigInteger(byte[] val).

For example, for a byte array of length 8 use:

String.format("%016X", new BigInteger(1,bytes))

Advantages:

• leading zeros
• no signum
• only built-in functions
• only one line of code

Disadvantage:

• there might be more efficient ways to do that

Example:

byte[] bytes = new byte[8];
Random r = new Random();
System.out.println("big-endian       | two's-complement");
System.out.println("-----------------|-----------------");
for (int i = 0; i < 10; i++) {
    r.nextBytes(bytes);
    System.out.print(String.format("%016X", new BigInteger(1,bytes)));
    System.out.print(" | ");
    System.out.print(String.format("%016X", new BigInteger(bytes)));
    System.out.println();
}

Example output:

big-endian       | two's-complement
-----------------|-----------------
3971B56BC7C80590 | 3971B56BC7C80590
64D3C133C86CCBDC | 64D3C133C86CCBDC
B232EFD5BC40FA61 | -4DCD102A43BF059F
CD350CC7DF7C9731 | -32CAF338208368CF
82CDC9ECC1BC8EED | -7D3236133E437113
F438C8C34911A7F5 | -BC7373CB6EE580B
5E99738BE6ACE798 | 5E99738BE6ACE798
A565FE5CE43AA8DD | -5A9A01A31BC55723
032EBA783D2E9A9F | 032EBA783D2E9A9F
8FDAA07263217ABA | -70255F8D9CDE8546