Android implements Google plus mConnectionResult.hasResolution () login error

Question

I learned google plus login from https://developers.google.com/+/mobile/android/getting-started

When I launch my application, the message "User connected!" Appears. and then I press the "G +" button to close my application power.

This is the logcat message form

04-08 18:31:21.680 24231-24231/app.umitems.test.testgoogleplus1.app D/﹕ onClick() 04-08 18:31:21.680 24231-24231/app.umitems.test.testgoogleplus1.app D/AndroidRuntime﹕ Shutting down VM 04-08 18:31:21.680 24231-24231/app.umitems.test.testgoogleplus1.app W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x41f99ce0) 04-08 18:31:21.685 24231-24231/app.umitems.test.testgoogleplus1.app E/AndroidRuntime﹕ FATAL EXCEPTION: main Process: app.umitems.test.testgoogleplus1.app, PID: 24231 java.lang.NullPointerException at app.umitems.test.testgoogleplus1.app.ExampleActivity.resolveSignInError(ExampleActivity.java:68) at app.umitems.test.testgoogleplus1.app.ExampleActivity.onClick(ExampleActivity.java:166) at com.google.android.gms.common.SignInButton.onClick(Unknown Source) at android.view.View.performClick(View.java:4445) at android.view.View$PerformClick.run(View.java:18446) at android.os.Handler.handleCallback(Handler.java:733) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5081) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:607) at dalvik.system.NativeStart.main(Native Method) 

Here is my code

 package app.umitems.test.testgoogleplus1.app; import android.app.Activity; import android.content.Intent; import android.content.IntentSender; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Toast; import com.google.android.gms.common.ConnectionResult; import com.google.android.gms.common.GooglePlayServicesClient.ConnectionCallbacks; import com.google.android.gms.common.GooglePlayServicesClient.OnConnectionFailedListener; import com.google.android.gms.common.api.GoogleApiClient; import com.google.android.gms.plus.Plus; public class ExampleActivity extends Activity implements ConnectionCallbacks, OnConnectionFailedListener, GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, View.OnClickListener { /* Request code used to invoke sign in user interactions. */ private static final int RC_SIGN_IN = 0; /* Client used to interact with Google APIs. */ private GoogleApiClient mGoogleApiClient; /* A flag indicating that a PendingIntent is in progress and prevents * us from starting further intents. */ private boolean mIntentInProgress; /* Track whether the sign-in button has been clicked so that we know to resolve * all issues preventing sign-in without waiting. */ private boolean mSignInClicked; /* Store the connection result from onConnectionFailed callbacks so that we can * resolve them when the user clicks sign-in. */ private ConnectionResult mConnectionResult; View btn; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_example); mGoogleApiClient = new GoogleApiClient.Builder(this) .addConnectionCallbacks(this) .addOnConnectionFailedListener(this) .addApi(Plus.API, null) //.addScope(Plus.SCOPE_PLUS_LOGIN) .build(); btn = findViewById(R.id.sign_in_button); btn.setOnClickListener(this); } protected void onStart() { super.onStart(); mGoogleApiClient.connect(); } /* A helper method to resolve the current ConnectionResult error. */ public void resolveSignInError() { Log.d("","resolveSignInError()"); if (mConnectionResult.hasResolution()) { Log.d("","resolveSignInError() mConnectionResult.hasResolution()"); try { mIntentInProgress = true; /*startIntentSenderForResult(mConnectionResult.getIntentSender(), RC_SIGN_IN, null, 0, 0, 0);*/ mConnectionResult.startResolutionForResult(this, // your activity RC_SIGN_IN); } catch (IntentSender.SendIntentException e) { // The intent was canceled before it was sent. Return to the default // state and attempt to connect to get an updated ConnectionResult. Log.d("","resolveSignInError() mConnectionResult.hasResolution() catch"); mIntentInProgress = false; mGoogleApiClient.connect(); } } } protected void onStop() { super.onStop(); if (mGoogleApiClient.isConnected()) { mGoogleApiClient.disconnect(); } } @Override public void onConnected(Bundle bundle){ // We've resolved any connection errors. mGoogleApiClient can be used to // access Google APIs on behalf of the user. mSignInClicked = false; Toast.makeText(this, "User is connected!", Toast.LENGTH_LONG).show(); } @Override public void onConnectionSuspended(int i){ mGoogleApiClient.connect(); } @Override public void onDisconnected(){ } @Override public void onConnectionFailed(ConnectionResult result) { if (!mIntentInProgress) { // Store the ConnectionResult so that we can use it later when the user clicks // 'sign-in'. mConnectionResult = result; if (mSignInClicked) { // The user has already clicked 'sign-in' so we attempt to resolve all // errors until the user is signed in, or they cancel. resolveSignInError(); } } } /*@Override public void onConnectionFailed(ConnectionResult result){ if (!mIntentInProgress && result.hasResolution()) { try { mIntentInProgress = true;*//* startIntentSenderForResult(result.getIntentSender(), RC_SIGN_IN, null, 0, 0, 0);*//* result.startResolutionForResult(this, // your activity RC_SIGN_IN); } catch (IntentSender.SendIntentException e) { // The intent was canceled before it was sent. Return to the default // state and attempt to connect to get an updated ConnectionResult. mIntentInProgress = false; mGoogleApiClient.connect(); } } }*/ protected void onActivityResult(int requestCode, int responseCode, Intent intent) { if (requestCode == RC_SIGN_IN) { if (responseCode != RESULT_OK) { mSignInClicked = false; } mIntentInProgress = false; if (!mGoogleApiClient.isConnecting()) { mGoogleApiClient.connect(); } } } @Override public void onClick(View view){ Log.d("","onClick()"); if (view.getId() == R.id.sign_in_button && !mGoogleApiClient.isConnecting()) { mSignInClicked = true; resolveSignInError(); } } } 

I just discovered that the application will automatically connect to Google+ without any permissions. I do not need to press the login button, but I can send messages through my account. Is this a mistake about privacy?

Answer 1

OK! So the toast is that you are logged in, and when you click the button, you are trying to log in again: because you have no connection result with an error for the solution, you get NPE.

Here's how it works:

• Your login state is stored on Google Play Services.
• When you connect, your application connects to Google Play services and tries to see if you have been previously signed up.
• If you have it, it accesses onConnected.
• If you have not done so, it calls onConnectionFailed and gives you ConnectionResult.
• When you click the login button, you "resolve the error" on ConnectionResult - this is only a pending intention that launches the account selection and consent screen.
• When the user agrees, your application returns to onActivityResult and you reconnect (and the thread starts again, this time ending in step 3).

So, if you get onConnected, you must hide the login button - the user has logged in!

Now, perhaps for some reason you want the user to click a button to start. It's also good. In onClick, you just need to check if mPlusClient isConnected. If so, go straight to what you wanted to do after logging in. If not, then allow the result of the connection.