title: Android facebook force logout
body: <p>I wan't to force logout from facebook when I exit the application so I have to login every time I start the application. If that is not possible I need help with checking if a user is already logged in.</p>
  
  <pre><code> private FacebookCallback&lt;LoginResult&gt; mCallback = new FacebookCallback&lt;LoginResult&gt;() {
          @Override
          public void onSuccess(final LoginResult loginResult) {
              GraphRequest request = GraphRequest.newMeRequest(
                      loginResult.getAccessToken(),
                      new GraphRequest.GraphJSONObjectCallback() {
                          @Override
                          public void onCompleted(
                                  JSONObject object,
                                  GraphResponse response) {
  
                              try {
                                  if (object != null) {
                                      name  = object.getString("first_name") + " "+object.getString("last_name");
                                      email = object.getString("email");
                                      mTextDetails.setText("Welcome " + name);
                                      editor.putString("username", name);
                                      editor.putString("email", email);
                                      editor.apply();
                                  }
                              } catch (JSONException e) {
  
                              }
                          }
                      });
              Bundle parameters = new Bundle();
              parameters.putString("fields", "id,name,email, first_name, last_name, gender");
              request.setParameters(parameters);
              request.executeAsync();
          }
  //        }
  
          @Override
          public void onCancel() {
          }
  
          @Override
          public void onError(FacebookException error) {
  
          }
      };
  
      public MainFragment() {
          // Required empty public constructor
      }
  
      public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          FacebookSdk.sdkInitialize(getActivity().getApplicationContext());
          mCallbackManager = CallbackManager.Factory.create();
      }
  
      @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container,
                               Bundle savedInstanceState) {
          View view = inflater.inflate(R.layout.fragment_main, container, false);
          mTextDetails = (TextView) view.findViewById(R.id.text_details);
          LoginButton loginButton = (LoginButton) view.findViewById(R.id.login_button);
          loginButton.setReadPermissions("public_profile", "email");//Only ask if you must
  
          loginButton.setFragment(this);
          loginButton.registerCallback(mCallbackManager, mCallback);
  
          sharedPref = this.getActivity().getSharedPreferences("userinfo", Context.MODE_PRIVATE);
          editor = sharedPref.edit();
          name = sharedPref.getString("username", "");
          email = sharedPref.getString("email","");
  
          if (name != "") {
              mTextDetails.setText(name);
          }
  //        Toast.makeText(getActivity(), sharedPref.getString("username", ""), Toast.LENGTH_LONG).show();
          Toast.makeText(getActivity(), sharedPref.getString("email", ""), Toast.LENGTH_LONG).show();
  
          return view;
      }
  
      public void onActivityResult(int requestCode, int resultCode, Intent data) {
          super.onActivityResult(requestCode, resultCode, data);
          mCallbackManager.onActivityResult(requestCode, resultCode, data);
  
  
      }
  }
  </code></pre>