JavaFX: How to check if page available or not

In my project I use simple JavaFX browser, that works in background and do some stuff without displaying it.

More precisely it submitted some form to one online page.

So, I ran into a problem: when this page doesn't available, I can't figure it out from my Java code, it looks like form wasn't submitted and clicks on Submit button do nothing, but in Chrome for example I see that the page isn't available.

So, is there an option to check from Java code if page is available?

Thanks in advance and sorry for bad English.