How do I set a proxy for firefox using Selenium webdriver with Java?

Question

System.setProperty("webdriver.gecko.driver", "E:\\geckodriver-v0.18.0-win64\\geckodriver.exe");
    Proxy p = new Proxy();
    p.setSocksProxy("83.209.94.87:35923");
    DesiredCapabilities cap = new DesiredCapabilities();
    cap.setCapability(CapabilityType.PROXY, p);
    WebDriver driver = new FirefoxDriver(cap);
    driver.get("https://www.google.com.au");

This code is inside the main method. When I run this code, firefox is launched but the google url isn't followed and the proxy is not set to the one I specify in the code above. How can I fix this?

public static void main(String[] args) throws InterruptedException, IOException, UnsupportedEncodingException {
    while (true) {
    System.setProperty("webdriver.gecko.driver", "E:\\geckodriver-v0.18.0-win64\\geckodriver.exe");
    WebDriver driver;
    String PROXY = "83.209.94.87:35923";
      //Bellow given syntaxes will set browser proxy settings using DesiredCapabilities.
      Proxy proxy = new Proxy();
      proxy.setAutodetect(false);
      proxy.setProxyType(Proxy.ProxyType.MANUAL);
      proxy.setSocksProxy(PROXY);
      DesiredCapabilities cap = new DesiredCapabilities();
      cap.setCapability(CapabilityType.PROXY, proxy);
      //Use Capabilities when launch browser driver Instance.
      driver = new FirefoxDriver(cap);`

Answer 1

Because a bug you cannot use the Proxy object as of now. You should use the below code

    FirefoxProfile profile = new FirefoxProfile();
    profile.setPreference("network.proxy.type", 1);
    profile.setPreference("network.proxy.socks", "83.209.94.87");
    profile.setPreference("network.proxy.socks_port", 35923);

    FirefoxDriver driver = new FirefoxDriver(profile);
    driver.get("https://www.ipinfo.io");

The bug is discussed on https://github.com/mozilla/geckodriver/issues/764 and you see what the Marionette driver do in background on below link

https://dxr.mozilla.org/mozilla-central/source/testing/marionette/session.js#155

So above code just replicates the same