how to show the hex detail of a file in java

To show the hexadecimal representation of a file in Java, you can use the readAllBytes method of the Files class to read the contents of the file into a byte array, and then use a loop to iterate through the array and convert each byte to its hexadecimal representation.

Here's an example of how you can do this:

import java.nio.file.Files;
import java.nio.file.Paths;

public class Main {
    public static void main(String[] args) throws Exception {
        byte[] data = Files.readAllBytes(Paths.get("/path/to/file.bin"));

        for (byte b : data) {
            System.out.printf("%02x ", b);
        }
    }
}

This code will read the contents of the file into a byte array, and then iterate through the array and print the hexadecimal representation of each byte to the console. The %02x format specifier is used to print each byte as a two-digit hexadecimal number, with leading zeros if necessary.

You can also use a utility class or library to handle the conversion of the bytes to hexadecimal. For example, you can use the Hex class from the commons-codec library to convert the byte array to a hexadecimal string:

import org.apache.commons.codec.binary.Hex;

public class Main {
    public static void main(String[] args) throws Exception {
        byte[] data = Files.readAllBytes(Paths.get("/path/to/file.bin"));
        String hex = Hex.encodeHexString(data);
        System.out.println(hex);
    }
}

This code will read the contents of the file into a byte array and convert it to a hexadecimal string using the encodeHexString method of the Hex class. The hexadecimal string can then be printed to the console or stored in a variable for further processing.