I have a byte array filled with hex numbers and printing it the easy way is pretty pointless because there are many unprintable elements. What I need is the exact hexcode in the form of: 3a5f771c
To convert a byte to hexadecimal equivalent, use the toHexString() method in Java. Firstly, let us take a byte value. byte val1 = (byte)90; Before using the method, let us do some more manipulations.
To convert byte array to a hex value, we loop through each byte in the array and use String 's format() . We use %02X to print two places ( 02 ) of Hexadecimal ( X ) value and store it in the string st .
Given a Byte value in Java, the task is to convert this byte value to string type. One method is to create a string variable and then append the byte value to the string variable with the help of + operator. This will directly convert the byte value to a string and add it in the string variable.
From the discussion here, and especially this answer, this is the function I currently use:
private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray(); public static String bytesToHex(byte[] bytes) { char[] hexChars = new char[bytes.length * 2]; for (int j = 0; j < bytes.length; j++) { int v = bytes[j] & 0xFF; hexChars[j * 2] = HEX_ARRAY[v >>> 4]; hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F]; } return new String(hexChars); }
My own tiny benchmarks (a million bytes a thousand times, 256 bytes 10 million times) showed it to be much faster than any other alternative, about half the time on long arrays. Compared to the answer I took it from, switching to bitwise ops --- as suggested in the discussion --- cut about 20% off of the time for long arrays. (Edit: When I say it's faster than the alternatives, I mean the alternative code offered in the discussions. Performance is equivalent to Commons Codec, which uses very similar code.)
2k20 version, with respect to Java 9 compact strings:
private static final byte[] HEX_ARRAY = "0123456789ABCDEF".getBytes(StandardCharsets.US_ASCII); public static String bytesToHex(byte[] bytes) { byte[] hexChars = new byte[bytes.length * 2]; for (int j = 0; j < bytes.length; j++) { int v = bytes[j] & 0xFF; hexChars[j * 2] = HEX_ARRAY[v >>> 4]; hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F]; } return new String(hexChars, StandardCharsets.UTF_8); }
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