Main.java

public static void main(String[] args) throws IOException {
  File file = new File( "D:\\test images\\8.png" );
  
  long start = System.nanoTime();
  ImageCrypto.applyXor(file);
  long end = System.nanoTime() - start;
  
  System.out.printf("Took: %d nanoseconds or %d milliseconds\n", end, (end/1000000));
}

Output:
Took: 1085333 nanoseconds or 1 milliseconds