mGoogleApiClient cannot be achieved in another activity

Question

I met a problem in my project. I want to use "Google API" to log in in my LoginActivity. And Log out from another Activity(named WelcomeActivity)

LoginActivity: (code is here)

public class LoginActivity extends AppCompatActivity implements
        GoogleApiClient.OnConnectionFailedListener,
        View.OnClickListener {

    // Configuration of Google API - Step 1/3
    private static final String TAG = "LoginActivity";
    private static final int RC_SIGN_IN = 9001;
    public static GoogleApiClient mGoogleApiClient;
    private ProgressDialog mProgressDialog;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        GoogleAPI();

    }
    public void GoogleAPI(){

        // Button listeners
        findViewById(R.id.sign_in_button).setOnClickListener(this);

        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestEmail()
                .build();

        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .enableAutoManage(this /* FragmentActivity */, this /* OnConnectionFailedListener */)
                .addApi(Auth.GOOGLE_SIGN_IN_API, gso)
                .build();
    }

    @Override
    public void onStart() {
        super.onStart();
        ....
    }

    // [START onActivityResult]
    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...);
        if (requestCode == RC_SIGN_IN) {
            GoogleSignInResult result = Auth.GoogleSignInApi.getSignInResultFromIntent(data);
            handleSignInResult(result);
        }
    }
    // [END onActivityResult]

    // [START handleSignInResult]
    private void handleSignInResult(GoogleSignInResult result) {

        if (result.isSuccess()) {
            // Signed in successfully, show authenticated UI.
            CustomApplication app = (CustomApplication)getApplication();
            GoogleSignInAccount acct = result.getSignInAccount();
            Intent i = new Intent(LoginActivity.this, WelcomePage.class);
            i.putExtra("Username", acct.getDisplayName());
            startActivity(i);
        }
    }
    // [END handleSignInResult]

    // [START signIn]
    private void signIn() {
        Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient);
        startActivityForResult(signInIntent, RC_SIGN_IN);
    }
    // [END signIn]

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        ...
    }

    private void showProgressDialog() {
       ...
    }

    private void hideProgressDialog() {
       ...
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.sign_in_button:
                signIn();
                break;
            ….
        }
    }

}

And I want to use Sign_out Method in my Welcome activity,

private void signOut() {
//        Auth.GoogleSignInApi.signOut(mGoogleApiClient).setResultCallback(
//                new ResultCallback<Status>() {
//                    @Override
//                    public void onResult(Status status) {
//                        // [START_EXCLUDE]
////                        updateUI(false);
//                        // [END_EXCLUDE]
//                    }
//                });
//    }

In order to solve this problem, i try 2 methods:

1. make mGoogleApiClient as a global variable(extends Application or Singleton), i try it, but failed, in Welcome page, mGoogleApiClient is not null, but error is: mGoogleApiClient is not connected yet.

2. i call LoginActivity.getMGoogleApiClient(static variable), but also failed, same error: mGoogleApiClient is not connected yet.

I already search this problem for days, but nothing useful to solve it, please help me ..

Answer 1

When you enableAutoManage, then the googleApiClient gets connected onStart and gets disconnected onStop and is handled automatically by the library. What you could is, logout the user in the other activity, whatever your code is to logout the user from your backend, except don't sign out from google yet.

Pseudo code:

private void logOut(){
    //your logout code in the log out activity

    setCurrentUser(null);
}

And in the activity with the googleApiClient, you could check if the user is logged-in in onConnected callback of googleApiClient. If the current user is not logged in, sign out the user from Google.

@Override
public void onConnected(Bundle connectionHint) {

    if (getCurrentUser() == null){
        signOut();
    }

}

private void signOut() {
    Auth.GoogleSignInApi.signOut(mGoogleApiClientPlus).setResultCallback(
            new ResultCallback<Status>() {
                @Override
                public void onResult(Status status) {
                    //signed out.
                }
            });
}

If you don't use enableAutoManage and don't disconnect the client in onStop (which I don't know if it's recommended), you could use your 2 methods but I won't recommend using static fields for googleApiClient object.

Answer 2

One solution is to do your normal logout flow (ignore mGoogleApiClient). The next time the user opens your app to the login screen and hits google login, you log them out first, then do the google login

e.g.:

private void googleLogin() {
  googleLogout();
  Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient);
  startActivityForResult(signInIntent, RC_SIGN_IN);
}

private void googleLogout() {
  if (mGoogleApiClient.isConnected()) {
    Auth.GoogleSignInApi.signOut(mGoogleApiClient);
  }
}