LoginButton

LoginActivity.java

mLoginButton.setReadPermissions("public_profile", "email");

        mLoginButton.registerCallback(mCallbackManager, new FacebookCallback<LoginResult>() {
            @Override
            public void onSuccess(LoginResult loginResult) {
                Timber.e("Result:" + loginResult.getAccessToken());
                gotFacebookPermission = true;
                startRequestingFacebookStaff(loginResult.getAccessToken());
            }

            @Override
            public void onCancel() {

            }

            @Override
            public void onError(FacebookException e) {

            }
        });