callbackManager = CallbackManager.Factory.create();

        loginButton = (LoginButton) findViewById(R.id.button_facebook_sign_in);
        loginButton.setReadPermissions("email");

        // Callback registration
        loginButton.registerCallback(callbackManager, new FacebookCallback<LoginResult>() {
            @Override
            public void onSuccess(LoginResult loginResult) {
                Intent intent = new Intent(LoginActivity.this, MainActivity.class);
                startActivity(intent);
                finish();

                Toast.makeText(LoginActivity.this, loginResult.getAccessToken().toString(), Toast.LENGTH_SHORT).show();

                Log.v("KJA onSuccess", "Facebook Login succeeded");
            }

            @Override
            public void onCancel() {
                // App code
                Log.v("KJA onCancel", "Cancel called");
            }

            @Override
            public void onError(FacebookException exception) {
                // App code
                Log.v("KJA onError", exception.toString());
            }
        });

loginButton.registerCallback(callbackManager, new FacebookCallback<LoginResult>() {

                @Override
                public void onSuccess(LoginResult loginResult) {

                    GraphRequest request = GraphRequest.newMeRequest(loginResult.getAccessToken(), new GraphRequest.GraphJSONObjectCallback() {

                        @Override
                        public void onCompleted(JSONObject object, GraphResponse response) {
                            Log.v("LoginActivity", response.toString());
                            if (object.has("picture")) {
                                try {
                                    String profilePicUrl = object.getJSONObject("picture").getJSONObject("data").getString("url");
                                    String nameOfUser = object.getString("name");
                                    String id = object.getString("id");
                                    Log.w("facebook_id", id);
                                    Log.w("facebook_name", nameOfUser);
                                    Log.w("facebook_pic", profilePicUrl);

                                } catch (JSONException e) {
                                    e.printStackTrace();
                                }
                            }
                        }
                    });
                    Bundle parameters = new Bundle();
                    parameters.putString("fields", "id,name,email,picture.type(large)");
                    request.setParameters(parameters);
                    request.executeAsync();
                }

                @Override
                public void onCancel() {

                }

                @Override
                public void onError(FacebookException e) {

                }
            }
    );

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    callbackManager.onActivityResult(requestCode, resultCode, data);
}