title: Implementing sign in with Google, And getting weird "unfortunately, MyApp has stopped"
body: <p>I have implemented Google Sign-In button in my app.</p>
  
  <p><img src="https://i.stack.imgur.com/m0hB5.png" alt="Google Sign in Button image"></p>
  
  <p>Everything works really well except one thing, when the intent prompts the user to select a Google account to sign in with, if the user press the back button he will get <code>unfortunately, MyApp has stopped</code> and the app will crash.</p>
  
  <p>I really don't know where should I start for picking a solution for this problem, any help would be appreciated.</p>
  
  <p>Hers is a sample of the code:</p>
  
  <pre><code>private SignInButton googleLogin;
  private GoogleApiClient apiClient;
  private GoogleSignInOptions gso;
  private String googleUserName;
  private String googleUserMail;
  private static final int REQ_ID = 9001;
  
  gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
              .requestEmail()
              .build();
      apiClient = new GoogleApiClient.Builder(this)
              .enableAutoManage(this,this)
              .addApi(Auth.GOOGLE_SIGN_IN_API, gso)
              .build();
  
      googleLogin = (SignInButton) findViewById(R.id.googleSignIn);
      googleLogin.setSize(SignInButton.SIZE_STANDARD);
      googleLogin.setScopes(gso.getScopeArray());
  
  googleLogin.setOnClickListener(new View.OnClickListener() {
              @Override
              public void onClick(View v) {
                  Intent signIntent = Auth.GoogleSignInApi.getSignInIntent(apiClient);
                  startActivityForResult(signIntent,REQ_ID);
              }
          });
  
  @Override
  protected void onActivityResult(final int requestCode, final int resultCode, final Intent data) {
      super.onActivityResult(requestCode, resultCode, data);
      callbackManager.onActivityResult(requestCode, resultCode, data);
      if(requestCode == REQ_ID)
      {
          GoogleSignInResult res = Auth.GoogleSignInApi.getSignInResultFromIntent(data);
          GoogleSignInAccount account = res.getSignInAccount();
          googleUserName = account.getDisplayName().toString();
          googleUserMail = account.getEmail().toString();
  
  
      }
  }
  @Override
  public void onConnectionFailed(ConnectionResult connectionResult) {
  
  }
  </code></pre>
  
  <p>And here is the log:</p>
  
  <pre><code>`05-27 06:06:56.420 22660-22738/com.MyApp W/EGL_emulation: eglSurfaceAttrib not implemented
  05-27 06:06:56.420 22660-22738/com.MyApp W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0x99ada7c0, error=EGL_SUCCESS
  05-27 06:07:03.147 22660-22660/com.MyApp D/AndroidRuntime: Shutting down VM
  05-27 06:07:03.147 22660-22660/com.MyApp E/AndroidRuntime: FATAL EXCEPTION: main
                                                                         Process: com.MyApp, PID: 22660
                                                                         java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=9001, result=0, data=Intent { (has extras) }} to activity {com.MyApp/com.MyApp.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.google.android.gms.auth.api.signin.GoogleSignInAccount.getDisplayName()' on a null object reference
                                                                             at android.app.ActivityThread.deliverResults(ActivityThread.java:3699)
                                                                             at android.app.ActivityThread.handleSendResult(ActivityThread.java:3742)
                                                                             at android.app.ActivityThread.-wrap16(ActivityThread.java)
                                                                             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1393)
                                                                             at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                             at android.os.Looper.loop(Looper.java:148)
                                                                             at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                                             at java.lang.reflect.Method.invoke(Native Method)
                                                                             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                                             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
                                                                          Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.google.android.gms.auth.api.signin.GoogleSignInAccount.getDisplayName()' on a null object reference
                                                                             at com.door.global.store.MainActivity.onActivityResult(MainActivity.java:200)
                                                                             at android.app.Activity.dispatchActivityResult(Activity.java:6428)
                                                                             at android.app.ActivityThread.deliverResults(ActivityThread.java:3695)
                                                                             at android.app.ActivityThread.handleSendResult(ActivityThread.java:3742) 
                                                                             at android.app.ActivityThread.-wrap16(ActivityThread.java) 
                                                                             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1393) 
                                                                             at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                             at android.os.Looper.loop(Looper.java:148) 
                                                                             at android.app.ActivityThread.main(ActivityThread.java:5417) 
                                                                             at java.lang.reflect.Method.invoke(Native Method) 
                                                                             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
                                                                             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
  `
  </code></pre>