Here's an example of how to use the HexDump class from the org.apache.commons.io package in Java to display a hex dump of a byte array:

import org.apache.commons.io.HexDump;

public class Main {
    public static void main(String[] args) {
        byte[] data = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08};
        HexDump.dump(data, 0, System.out, 0);
    }
}

This example shows how to use the dump() method from the HexDump class to display a hex dump of a byte array. The method takes the byte array, an offset, an output stream, and a number of bytes per line as arguments. The hex dump will be written to the specified output stream.

It's important to note that HexDump class is a utility class used to display byte arrays in a human-readable format, and it's not specific to work with files, it's mainly used for debugging purposes.