what is and how to get the pinCode for Twitter and oauth-signpost?

i don't know what is the pinCode and i don't how to get it ?! i found the following code, as mentioned we can get it from CallBack, how can ? and if there is another method please show me ..

the code

OAuthConsumer consumer = new DefaultOAuthConsumer(
                // the consumer ke开发者_开发知识库y of this app (replace this with yours)
                "iIlNngv1KdV6XzNYkoLA",
                // the consumer secret of this app (replace this with yours)
                "exQ94pBpLXFcyttvLoxU2nrktThrlsj580zjYzmoM");

        OAuthProvider provider = new DefaultOAuthProvider(
                "http://twitter.com/oauth/request_token",
                "http://twitter.com/oauth/access_token",
                "http://twitter.com/oauth/authorize");

        /****************************************************
         * The following steps should only be performed ONCE
         ***************************************************/

        // we do not support callbacks, thus pass OOB
        String authUrl = provider.retrieveRequestToken(consumer, OAuth.OUT_OF_BAND);

        // bring the user to authUrl, e.g. open a web browser and note the PIN code
        // ...         

        String pinCode = // ... you have to ask this from the user, or obtain it
        // from the callback if you didn't do an out of band request

        // user must have granted authorization at this point
        provider.retrieveAccessToken(consumer, pinCode);

        // store consumer.getToken() and consumer.getTokenSecret(),
        // for the current user, e.g. in a relational database
        // or a flat file
        // ...

        /****************************************************
         * The following steps are performed everytime you
         * send a request accessing a resource on Twitter
         ***************************************************/

        // if not yet done, load the token and token secret for
        // the current user and set them
        consumer.setTokenWithSecret(ACCESS_TOKEN, TOKEN_SECRET);

        // create a request that requires authentication
        URL url = new URL("http://twitter.com/statuses/mentions.xml");
        HttpURLConnection request = (HttpURLConnection) url.openConnection();

        // sign the request
        consumer.sign(request);

        // send the request
        request.connect();

        // response status should be 200 OK
        int statusCode = request.getResponseCode();

---

The user must visit authUrl in a browser. The page will ask him to authorize the application and then tell him the pinCode. He must then enter the pinCode into your application.

The comments really describe this pretty well.