Confirming file content against hash

I have a requirement to 'check the integrity' of the content of files. The files will be written to CD/DVD, which might be copied many times. The idea is to identify copies (after they are removed from Nero etc.) which copied correctly.

Am rather new to this, but a quick search suggests that Arrays.hashCode(byte[]) will fit the need. We can include a file on the disk that contains the result of that call for each resource of interest, then compare it to the byte[] of the File as read from disk when checked.

Do I understand the method correctly, is this a valid way to go about checking file content?

If not, suggestions as to search keywords or strategies/methods/classes would be appreciated.

Working code based on the answer of Brendan. It takes care of the problem identified by VoidStar (needing to hold the entire byte[] in memory for getting the hash).

import java.io.File;
import java.io.FileInputStream;
import java.util.zip.CRC32;

class TestHash {

    public static void main(String[] args) throws Exception {
        File f = new File("TestHash.java");
        FileInputStream fis = new FileInputStream(f);
        CRC32 crcMaker = new CRC32();
        byte[] buffer = new byte[65536];
        int bytesRead;
        while((bytesRead = fis.read(buffer)) != -1) {
            crcMaker.update(buffer, 0, bytesRead);
        }
        long crc = crcMaker.getValue(); // This is your error checking code
        System.out.println("CRC code is " + crc);
    }
}

Solution

Arrays.hashCode() is designed to be very fast (used in hash tables). I highly recommend not using it for this purpose.

What you want is some sort of error-checking code like a CRC.

Java happens to have a class for calculating these: CRC32:

InputStream in = ...;
CRC32 crcMaker = new CRC32();
byte[] buffer = new byte[someSize];
int bytesRead;
while((bytesRead = in.read(buffer)) != -1) {
    crcMaker.update(buffer, 0, bytesRead);
}
long crc = crcMaker.getValue(); // This is your error checking code