getting java code for hashing files

private static String getFileChecksum(MessageDigest digest, File file) throws IOException
{
    //Get file input stream for reading the file content
    FileInputStream fis = new FileInputStream(file);
     
    //Create byte array to read data in chunks
    byte[] byteArray = new byte[1024];
    int bytesCount = 0; 
      
    //Read file data and update in message digest
    while ((bytesCount = fis.read(byteArray)) != -1) {
        digest.update(byteArray, 0, bytesCount);
    };
     
    //close the stream; We don't need it now.
    fis.close();
     
    //Get the hash's bytes
    byte[] bytes = digest.digest();
     
    //This bytes[] has bytes in decimal format;
    //Convert it to hexadecimal format
    StringBuilder sb = new StringBuilder();
    for(int i=0; i< bytes.length ;i++)
    {
        sb.append(Integer.toString((bytes[i] & 0xff) + 0x100, 16).substring(1));
    }
     
    //return complete hash
   return sb.toString();
}