Open Tor Browser:

File torProfileDir = new File(
        "...\\Tor Browser\\Data\\Browser\\profile.default");
FirefoxBinary binary = new FirefoxBinary(new File(
        "...\\Tor Browser\\Start Tor Browser.exe"));
FirefoxProfile torProfile = new FirefoxProfile(torProfileDir);
torProfile.setPreference("webdriver.load.strategy", "unstable");

try {
    binary.startProfile(torProfile, torProfileDir, "");
} catch (IOException e) {
    e.printStackTrace();
}
Open Firefox with some configurations:

FirefoxProfile profile = new FirefoxProfile();
profile.setPreference("network.proxy.type", 1);
profile.setPreference("network.proxy.socks", "127.0.0.1");
profile.setPreference("network.proxy.socks_port", 9150);
FirefoxDriver = new FirefoxDriver(profile);
Close browsers. Note that if you plan on doing a lot of closing and reopening (useful in obtaining a new IP address), I advise setting the profile preference toolkit.startup.max_resumed_crashes to a high value like 9999.

private void killFirefox() {
Runtime rt = Runtime.getRuntime();

try {
    rt.exec("taskkill /F /IM firefox.exe");

    while (processIsRunning("firefox.exe")) {
        Thread.sleep(100);
    }
}

catch (Exception e) {
    e.printStackTrace();
}
}

private boolean processIsRunning(String process) {
boolean firefoxIsRunning = false;
String line;
try {
    Process proc = Runtime.getRuntime().exec("wmic.exe");
    BufferedReader input = new BufferedReader(new InputStreamReader(proc.getInputStream()));
    OutputStreamWriter oStream = new OutputStreamWriter(proc.getOutputStream());
    oStream.write("process where name='" + process + "'");
    oStream.flush();
    oStream.close();
    while ((line = input.readLine()) != null) {
        if (line.toLowerCase().contains("caption")) {
            firefoxIsRunning = true;
            break;
        }
    }
    input.close();
} catch (IOException ioe) {
    ioe.printStackTrace();
}

return firefoxIsRunning;
}