A class to implement Facebook Login just in few functions.

FacebookLoginManager.java

/**
 * Created by harsu on 22-06-2016.
 * <p>
 * This class reduces the BoilerPlate code for Implementing Facebook Login by providing an easy to access class and functions.
 * <p>
 * 1. Create an instance of the class in your Sign in activity.
 * 2. Set a View whose onClick would Invoke Facebook Sign In Procedure along with the request params using {@link #setLoginView(View, Activity, Collection)}
 * or {@link #setLoginView(View, Fragment, Collection)}
 * 3. call the {@link #onActivityResult(int, int, Intent)} in your sign In activity's onActivityResult().
 * 4. store the data by implementing your logic in {@link #storeData(Map)}
 *
 */
public class FacebookLoginManager {
    Context context;
    CallbackManager callbackManager;
    AccessTokenTracker accessTokenTracker;
    ProfileTracker profileTracker;
    Callback callback;

    /**
     * Default constructor
     *
     * @param context
     * @param callback
     */
    public FacebookManager(Context context, final Callback callback) {
        this.context = context;
        this.callback = callback;
        FacebookSdk.sdkInitialize(context.getApplicationContext());
        callbackManager = CallbackManager.Factory.create();
        LoginManager.getInstance().registerCallback(callbackManager, new FacebookCallback<LoginResult>() {
            @Override
            public void onSuccess(LoginResult loginResult) {
                callback.onSuccess();
                facebookSignIn(loginResult);
            }

            @Override
            public void onCancel() {
                callback.onFailure(Error.REQUEST_CANCELLED);
            }

            @Override
            public void onError(FacebookException e) {
                callback.onFailure(Error.NO_INTERNET_CONNECTION);
            }
        });

    }

    /**
     * Call this function from the Activity's onActivityResult(...)
     *
     * @param requestCode
     * @param resultCode
     * @param data
     */
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        callbackManager.onActivityResult(requestCode, resultCode, data);
    }

    /**
     * Add a view as Login Starter.
     *
     * @param view
     * @param activity
     * @param readPermissions the Array list of permission to be requested.
     */
    public void setLoginView(View view, final Activity activity, final Collection<String> readPermissions) {
        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                LoginManager.getInstance().logInWithReadPermissions(activity, readPermissions);
            }
        });
    }
    
    
    /**
     * Add a view as Login Starter.
     *
     * @param view
     * @param fragment
     * @param readPermissions the Array list of permission to be requested.
     */
    public void setLoginView(View view, final Fragment fragment, final Collection<String> readPermissions) {
        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                LoginManager.getInstance().logInWithReadPermissions(fragment, readPermissions);
            }
        });
    }

    private void facebookSignIn(LoginResult loginResult) {
        GraphRequest request = GraphRequest.newMeRequest(loginResult.getAccessToken(), new GraphRequest.GraphJSONObjectCallback() {

            @Override
            public void onCompleted(JSONObject object, GraphResponse response) {
                Log.i("LoginActivity", response.toString());
                // Get facebook data from login
                Map<String, String> params = new HashMap<>();
                try {
                    params.put("name", object.getString("name"));
                    params.put("email", object.getString("email"));
                    params.put("gender", object.getString("gender"));
                    params.put("user_name", object.getString("email"));
                    params.put("profilepic", object.getJSONObject("picture").getJSONObject("data").getString("url"));

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

                storeData(params);

            }

        });
        Bundle parameters = new Bundle();
        //all the fields Required to extract from Graph API
        parameters.putString("fields", "name, email,gender,picture.type(large) ");
        request.setParameters(parameters);
        request.executeAsync();
    }

    /**
     * implement send data to server logic or store to a local database. On success or failure of the implemented logic
     * call {@link Callback#onSuccess()} , call {@link Callback#onFailure(int)} using the error code from {@link Error},
     * To receive proper callBacks to the Caller Activity and Enabling it's Flow.
     *
     * @param params
     */
    private void storeData(Map<String, String> params) {

    }

    /**
     * Call this function to logout of Facebook.
     * It gives a {@link Callback#onSuccess()} if successfully Executed.
     * <p>
     * You can further branch out to remove data from server or local Database and finally call
     * {@link Callback#onSuccess()}.
     */
    public void logout() {
        LoginManager.getInstance().logOut();
        //branch out from here if needed

        callback.onSuccess();
    }

    /**
     *
     */
    public void startTracking() {
        accessTokenTracker = new AccessTokenTracker() {
            @Override
            protected void onCurrentAccessTokenChanged(
                    AccessToken oldAccessToken,
                    AccessToken currentAccessToken) {
                AccessToken.setCurrentAccessToken(currentAccessToken);
            }
        };
        profileTracker = new ProfileTracker() {
            @Override
            protected void onCurrentProfileChanged(
                    Profile oldProfile,
                    Profile currentProfile) {
                Profile.setCurrentProfile(currentProfile);

            }
        };
        accessTokenTracker.startTracking();
    }

    public void stopTracking() {
        if (accessTokenTracker != null && profileTracker != null) {
            accessTokenTracker.stopTracking();
            profileTracker.stopTracking();
        }
    }


    /**
     * CallBack to receive  success or failure of login, logout.
     */
    public interface Callback {
        public void onSuccess();

        public void onFailure(int error);
    }

    /**
     * store int values of error that this class can throw
     */
    public interface Error {
        int NO_INTERNET_CONNECTION = 0;
        int REQUEST_CANCELLED = 1;
    }