Ich habe die Google-Entwicklerdokumentation ausprobiert und versucht, mich für meine App anzumelden. Der Code wird aus dem Git mit hinzugefügten Codes aus dem @ kopierDokumentation und definiert in LoginActivity wi

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

private static final String TAG = "* * SignIn * *";
private static final int RC_SIGN_IN = 9001;

private GoogleApiClient mGoogleApiClient;
private ProgressDialog mProgressDialog;
Bundle userData = new Bundle();
Intent newIntent;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);
   findViewById(R.id.sign_in_button).setOnClickListener(this);


    // [START configure_signin]
    // Configure sign-in to request the user's ID, email address, and basic
    // profile. ID and basic profile are included in DEFAULT_SIGN_IN.
    GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
            .requestEmail()
            .build();
    // [END configure_signin]

    // [START build_client]
    mGoogleApiClient = new GoogleApiClient.Builder(this)
            .enableAutoManage(this /* FragmentActivity */, this /* OnConnectionFailedListener */)
            .addApi(Auth.GOOGLE_SIGN_IN_API, gso)
            .build();
    // [END build_client]

    // [START customize_button]
    SignInButton signInButton = (SignInButton) findViewById(R.id.sign_in_button);
    signInButton.setSize(SignInButton.SIZE_STANDARD);
    signInButton.setScopes(gso.getScopeArray());
    // [END customize_button]
}

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

    OptionalPendingResult<GoogleSignInResult> opr = Auth.GoogleSignInApi.silentSignIn(mGoogleApiClient);
    if (opr.isDone()) {
        Log.d(TAG, "Got cached sign-in");
        GoogleSignInResult result = opr.get();
        handleSignInResult(result);
    } else {

        showProgressDialog();
        opr.setResultCallback(new ResultCallback<GoogleSignInResult>() {
            @Override
            public void onResult(GoogleSignInResult googleSignInResult) {
                hideProgressDialog();
                handleSignInResult(googleSignInResult);
            }
        });
    }
}

// [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) {
    Log.d(TAG, "handleSignInResult:" + result.isSuccess());
    if (result.isSuccess()) {
        // Signed in successfully, show authenticated UI.
        GoogleSignInAccount acct = result.getSignInAccount();
        userData.putString("Username", acct.getDisplayName());
        userData.putString("Email",acct.getEmail());
        newIntent = new Intent(LoginActivity.this, MainActivity.class);
        newIntent.putExtras(userData);
        startActivity(newIntent);
        finish();
    } else {
        userData.putString("Username", "Anonymous");
        userData.putString("Email","www.example.com");
        newIntent = new Intent(LoginActivity.this, MainActivity.class);
        newIntent.putExtras(userData);
        startActivity(newIntent);
        finish();
    }
}
// [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) {
            Log.d(TAG, "onConnectionFailed:" + connectionResult);
}

private void showProgressDialog() {
    if (mProgressDialog == null) {
        mProgressDialog = new ProgressDialog(this);
        mProgressDialog.setMessage("Please wait");
        mProgressDialog.setIndeterminate(true);
    }

    mProgressDialog.show();
}

private void hideProgressDialog() {
    if (mProgressDialog != null && mProgressDialog.isShowing()) {
        mProgressDialog.hide();
    }
}
@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.sign_in_button:
            signIn();
            break;

    }
}

}

Aber ich bekomme folgenden FehlerLog wi

12-16 23:02:44.074 5545-5545/com.example.www.newapp E/AndroidRuntime: java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=40962, result=-1, data=Intent { (has extras) }} 
                                                                     to activity {com.example.www.newapp/com.google.android.gms.auth.api.signin.internal.SignInHubActivity}: 
                                                                    java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Class java.lang.Object.getClass()' on a null object reference

MyHauptaktivitä code ist wie

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener, View.OnClickListener {
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    View header = navigationView.getHeaderView(0);
    userName = (TextView) header.findViewById(R.id.userName);
    userName.setText(user);//Username recieved through intent
}}

Während es im Emulator ausgeführt wird, wird angezeigt, dass Ihr Wiedergabedienst aktualisiert wurde. Ist dies ein Problem?