需要帮助将 perlscript 转换为 java

Question

i need to convert this perlscript to java. But i can not read perl. Can somebdoy help me plz.

sub checksum16 ($) {
    my @bytes = unpack("C*", $_[0]);
    my $sum = 0;
    foreach(@bytes) {
        $sum += $_;
        $sum %= 2**16;
    }
    return $sum;
}

What is $_ and $_[0]? Its not defined and what is unpack("C*", ... for?

Answer 1

The "C*" means unsigned char (octet value), see perldoc pack , so you could try something like this:

public class Checksum
{
    public static void main(String [] args) throws Exception
    {
        String raw = new String(new byte[] {(byte) 0x40, (byte) 0x41});
        byte[] byteArrray = raw.getBytes();
        System.out.println("Result: " + checksum(byteArrray));
    }

    public static int checksum(byte[] arr) {
        int sum = 0;
        for (byte x : arr) {
            sum += x;
            sum %= 65536;
        }
        return sum;
    }
}

Update :

Java does not seem to have an unsigned byte type, so you can use int to hold the bytes instead:

public class Checksum
{
    public static void main(String [] args)
    {
        //use int instead of byte since byte is not unsigned
        int[] data = new int[] {0xff, 0x1};
        System.out.println("Result: " + checksum(data));
    }
    
     // assume input array "arr" is unsigned bytes
    public static int checksum(int[] arr) {
        int sum = 0;
        for (int x : arr) {
            // we assume input is unsigned bytes so we should not need to mask
            //  with 0xFF here
            int unsigned_byte = x & 0xFF;
            sum += unsigned_byte;
            sum %= 65536;
        }
        return sum;
    }
}