NullPointerException thrown when 'switchToNewUser()' method is called on StatefulAuthHelper

[HalfMillennium]

I took my code basically verbatim from the Android example, but changed some of the class names. That's about it, and everything works fine when I run the example app itself. The full error is as follows:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'net.dean.jraw.oauth.StatefulAuthHelper net.dean.jraw.oauth.AccountHelper.switchToNewUser()' on a null object reference at com.digitalnode.glc22.feedr.LogInActivities.RedditLogin.onCreate(RedditLogin.java:59)

The line it is referring to is below:

final StatefulAuthHelper helper = RedditAppHelper.getAccountHelper().switchToNewUser();

I figure it's a really simple mistake that I've made, but I'll post my full classes if needed.

[mattbdean]

basically verbatim

Please post code

[HalfMillennium]

Yep, sure thing. By that I meant literally the only thing I purposefully changed was the name of the class, but here's the code:

RedditAppHelper (Formerly App)

public final class RedditAppHelper extends Application {
    private static AccountHelper accountHelper;
    private static SharedPreferencesTokenStore tokenStore;

    @Override
    public void onCreate() {
        super.onCreate();

        // Get UserAgent and OAuth2 data from AndroidManifest.xml
        AppInfoProvider provider = new ManifestAppInfoProvider(getApplicationContext());

        // Ideally, this should be unique to every device
        UUID deviceUuid = UUID.randomUUID();

        // Store our access tokens and refresh tokens in shared preferences
        tokenStore = new SharedPreferencesTokenStore(getApplicationContext());
        // Load stored tokens into memory
        tokenStore.load();
        // Automatically save new tokens as they arrive
        tokenStore.setAutoPersist(true);

        // An AccountHelper manages switching between accounts and into/out of userless mode.
        accountHelper = AndroidHelper.accountHelper(provider, deviceUuid, tokenStore);

        // Every time we use the AccountHelper to switch between accounts (from one account to
        // another, or into/out of userless mode), call this function
        accountHelper.onSwitch(redditClient -> {
            // By default, JRAW logs HTTP activity to System.out. We're going to use Log.i()
            // instead.
            LogAdapter logAdapter = new SimpleAndroidLogAdapter(Log.INFO);

            // We're going to use the LogAdapter to write down the summaries produced by
            // SimpleHttpLogger
            redditClient.setLogger(
                    new SimpleHttpLogger(SimpleHttpLogger.DEFAULT_LINE_LENGTH, logAdapter));

            // If you want to disable logging, use a NoopHttpLogger instead:
            // redditClient.setLogger(new NoopHttpLogger());

            return null;
        });
    }

    public static AccountHelper getAccountHelper() { return accountHelper; }
    public static SharedPreferencesTokenStore getTokenStore() { return tokenStore; }
}

RedditLogin (Formerly NewUserActivity)

public class RedditLogin extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_reddit_log_in);

        // Don't save any cookies, cache, or history from previous sessions. If we don't, once the
        // first user logs in and authenticates, the next time we go to add a new user, the first
        // user will be automatically logged in, which is not what we want.
        final WebView webView = findViewById(R.id.webView);
        webView.clearCache(true);
        webView.clearHistory();

        // Stolen from https://github.com/ccrama/Slide/blob/a2184269/app/src/main/java/me/ccrama/redditslide/Activities/Login.java#L92
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1) {
            CookieManager.getInstance().removeAllCookies(null);
            CookieManager.getInstance().flush();
        } else {
            CookieSyncManager cookieSyncMngr = CookieSyncManager.createInstance(this);
            cookieSyncMngr.startSync();
            CookieManager cookieManager = CookieManager.getInstance();
            cookieManager.removeAllCookie();
            cookieManager.removeSessionCookie();
            cookieSyncMngr.stopSync();
            cookieSyncMngr.sync();
        }

        // Get a StatefulAuthHelper instance to manage interactive authentication
        final StatefulAuthHelper helper = RedditAppHelper.getAccountHelper().switchToNewUser();

        // Watch for pages loading
        webView.setWebViewClient(new WebViewClient() {
            @Override
            public void onPageStarted(WebView view, String url, Bitmap favicon) {
                if (helper.isFinalRedirectUrl(url)) {
                    // No need to continue loading, we've already got all the required information
                    webView.stopLoading();
                    webView.setVisibility(View.GONE);

                    // Try to authenticate the user
                    new AuthenticateTask(RedditLogin.this, helper).execute(url);
                }
            }
        });

        // Generate an authentication URL
        boolean requestRefreshToken = true;
        boolean useMobileSite = true;
        String[] scopes = new String[]{ "read", "identity" };
        String authUrl = helper.getAuthorizationUrl(requestRefreshToken, useMobileSite, scopes);

        // Finally, show the authorization URL to the user
        webView.loadUrl(authUrl);
    }

    /**
     * An async task that takes a final redirect URL as a parameter and reports the success of
     * authorizing the user.
     */
    private static final class AuthenticateTask extends AsyncTask<String, Void, Boolean> {
        // Use a WeakReference so that we don't leak a Context
        private final WeakReference<Activity> context;

        private final StatefulAuthHelper helper;

        AuthenticateTask(Activity context, StatefulAuthHelper helper) {
            this.context = new WeakReference<>(context);
            this.helper = helper;
        }

        @Override
        protected Boolean doInBackground(String... urls) {
            try {
                helper.onUserChallenge(urls[0]);
                return true;
            } catch (OAuthException e) {
                // Report failure if an OAuthException occurs
                return false;
            }
        }

        @Override
        protected void onPostExecute(Boolean success) {
            // Finish the activity if it's still running
            Activity host = this.context.get();
            if (host != null) {
                host.setResult(success ? Activity.RESULT_OK : Activity.RESULT_CANCELED, new Intent());
                host.finish();
            }
        }
    }
}

[HalfMillennium]

Is this anything you could possibly help with?

[HalfMillennium]

basically verbatim

Please post code

[HalfMillennium]

Sorry, I didn't mean to close this. If you can't help me, that's fine, but I think you might be the only person that could assist me with this very specific issue.

[HalfMillennium]

Wait, no, Matt, that was an accident, I didn't mean to quote you like that lol. I was just trying to make a comment.

[adityam49]

Fix that worked for me was that I added
android:name=".RedditAppHelper"
in the AndroidManifest file

[HalfMillennium]

Thanks, I'll try this out.