Sorry if it could easy for you, but have 2 days that I trying to find a working twitter sample, every sample stop when try to request token, reading twitter forum, people says that could be internal system clock, I´ve set to my local date and time.
Using:
public static final String REQUEST_URL = "http://api.twitter.com/oauth/request_token";
public static final String ACCESS_URL = "http://api.twitter.com/oauth/access_token";
public static final String AUTHORIZE_URL = "http://api.twitter.com/oauth/authorize";
Callback URL http://www.google.com (inside twitter Oauth Settings, people says to not leave it blank)
I already checked both tokens, and set to read and write.