Random Proxy + Proxy Login Issues

I'm wondering if it would be possible to randomize proxy usage using the code below. All of the proxies I plan to use have the same port, same login, but of course different IPs.

I'm also having issues with the proxy actually working, even without randomizing. When I test, it's still using my main IP.

Here's the code I'm trying to work with:

public class RandomIP {

public static void main (String [] args) {

    String [] proxyIP = {"123", "213", "314", "415"};
    Random random = new Random();

    int select = random.nextInt(proxyIP.length);

    System.out.println("Proxy selected: " + proxyIP[select]);
}

How could I implement this with my main program, what line would I need to add to have it reference to this? The program loops so of course I would want it to be a different IP every time.