public static String checkSum(String strFile) { // Declare variables CheckedInputStream cCheck = null; long lFileSize = 0; byte[] bBuf = new byte[1024]; try { // Computer CRC32 checksum cCheck = new CheckedInputStream(new FileInputStream(strFile), new CRC32()); // Get file size lFileSize = new File(strFile).length(); // Read all file to checksum while (cCheck.read(bBuf) >= 0) { } } catch (Exception eError) { System.err.println("Exception: " + eError); return null; } return cCheck.getChecksum().toString(); }