How to Convert and Print Byte array to Hex String in Java? Example

To convert a byte array to a hexadecimal string in Java, you can use the BigInteger class along with the String.format method. 

Here's an example:

import java.math.BigInteger;

public class ByteArrayToHexString {
    public static void main(String[] args) {
        byte[] byteArray = { 0x12, 0x34, (byte) 0xAB, (byte) 0xCD, (byte) 0xEF };

        // Convert byte array to BigInteger
        BigInteger bigInt = new BigInteger(1, byteArray);

        // Convert BigInteger to hexadecimal string
        String hexString = bigInt.toString(16);

        // Pad the string with leading zeros if necessary
        int paddingLength = (byteArray.length * 2) - hexString.length();
        if (paddingLength > 0) {
            hexString = String.format("%0" + paddingLength + "d", 0) + hexString;
        }

        // Print the hexadecimal string
        System.out.println(hexString);
    }
}

In this example, we have a byte array byteArray containing some bytes. We convert the byte array to a BigInteger using the constructor new BigInteger(1, byteArray). 

The 1 argument specifies that the byte array is positive. Then, we convert the BigInteger to a hexadecimal string using the toString(16) method call. 

The 16 argument specifies that we want to convert it to a hexadecimal string. Next, we check if the length of the hexadecimal string is smaller than the expected length (twice the length of the byte array). 

If so, we pad the string with leading zeros using the String.format method. Finally, we print the resulting hexadecimal string. 

The output of the example would be:

1234abcdef

Note: It's important to consider endianness when converting a byte array to a hexadecimal string. The example above assumes that the byte array is in big-endian format. 

If your byte array is in little-endian format, you'll need to reverse the byte array before converting it to a BigInteger.