NullPointerException on facebook login using servlet
- by khoyendra
after solve class notfound exeption i have to find error when i login in face book using given example  
http://code.google.com/p/facebook-java-api/wiki/Examples
java.lang.NullPointerException
    com.google.code.facebookapi.ExtensibleClient.<init>(ExtensibleClient.java:111)
    com.google.code.facebookapi.ExtensibleClient.<init>(ExtensibleClient.java:99)
    com.google.code.facebookapi.ExtensibleClient.<init>(ExtensibleClient.java:95)
    com.google.code.facebookapi.FacebookXmlRestClientBase.<init>(FacebookXmlRestClientBase.java:44)
    com.google.code.facebookapi.FacebookXmlRestClient.<init>(FacebookXmlRestClient.java:10)
    FaceBookCrawl.FacebookUserFilter.doFilter(FacebookUserFilter.java:107)
    FaceBookCrawl.FacebookUserFilter.doPost(FacebookUserFilter.java:181)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:803)