try {
        // Compute Adler-32 checksum
        CheckedInputStream cis = new CheckedInputStream(
            new FileInputStream("filename"), new Adler32());
        byte[] tempBuf = new byte[128];
        while (cis.read(tempBuf) >= 0) {
        }
        long checksum = cis.getChecksum().getValue();
    } catch (IOException e) {
    }