How to use cURL in Java?
You can make use of java.net.URL and/or java.net.URLConnection.
URL url = new URL("https://stackoverflow.com");try (BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"))) { for (String line; (line = reader.readLine()) != null;) { System.out.println(line); }}Also see the Oracle's simple tutorial on the subject. It's however a bit verbose. To end up with less verbose code, you may want to consider Apache HttpClient instead.
By the way: if your next question is "How to process HTML result?", then the answer is "Use a HTML parser. No, don't use regex for this.".
See also:
Some people have already mentioned HttpURLConnection, URL and URLConnection. If you need all the control and extra features that the curl library provides you (and more), I'd recommend Apache's httpclient.
The Runtime object allows you to execute external command line applications from Java and would therefore allow you to use cURL however as the other answers indicate there is probably a better way to do what you are trying to do. If all you want to do is download a file the URL object will work great.