如果用户已经登录，则在我的Android应用程序中使用谷歌登录会遇到麻烦

Question

I have problems with using google sign-in in my application if user is already logged in. When I log in the first time it works nice since it asks me for password and other information but if user is already logged in I thin that normally it should open choose account menu like this one:

[Screenshot][https://androidclarified.com/wp-content/uploads/2018/11/Screenshot_2018-11-11-20-53-15-306_com.google.android.gms_-768x1365.png]

But what happens in my case is the following: [problem-gif][https://gph.is/g/ZYBxy14]

public class LoginActivity extends AppCompatActivity implements
        View.OnClickListener{


    private static final String TAG = "LoginActivity1";
    private static final int RC_SIGN_IN = 9001;
    private GoogleSignInClient mGoogleSignInClient;

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

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

        mGoogleSignInClient = GoogleSignIn.getClient(this, gso);
        SignInButton signInButton = findViewById(R.id.sign_in_button);
        signInButton.setOnClickListener(this);
    }

    private void signIn() {
        Toast.makeText(this, "button works", Toast.LENGTH_SHORT).show();
        Intent signInIntent = mGoogleSignInClient.getSignInIntent();
        startActivityForResult(signInIntent, RC_SIGN_IN);
    }
    private void signOut() {
        mGoogleSignInClient.signOut()
                .addOnCompleteListener(this, new OnCompleteListener<Void>() {
                    @Override
                    public void onComplete(@NonNull Task<Void> task) {
                        // [START_EXCLUDE]
                        updateUI(null);
                        // [END_EXCLUDE]
                    }
                });
    }

    private void updateUI(@Nullable GoogleSignInAccount account) {
        if (account != null) {
            Log.d(TAG, account.getDisplayName());
        } else {
            Log.d(TAG, "account is null");
        }
    }

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

        // [START on_start_sign_in]
        // Check for existing Google Sign In account, if the user is already signed in
        // the GoogleSignInAccount will be non-null.
        GoogleSignInAccount account = GoogleSignIn.getLastSignedInAccount(this);
        updateUI(account);
        // [END on_start_sign_in]
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        // Result returned from launching the Intent from GoogleSignInClient.getSignInIntent(...);
        if (requestCode == RC_SIGN_IN) {
            // The Task returned from this call is always completed, no need to attach
            // a listener.
            Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
            handleSignInResult(task);
        }
    }

    private void handleSignInResult(Task<GoogleSignInAccount> completedTask) {
        try {
            GoogleSignInAccount account = completedTask.getResult(ApiException.class);

            // Signed in successfully, show authenticated UI.
            updateUI(account);
        } catch (ApiException e) {
            // The ApiException status code indicates the detailed failure reason.
            // Please refer to the GoogleSignInStatusCodes class reference for more information.
            Log.d(TAG, "signInResult:failed code=" + e.getStatusCode());
            updateUI(null);
        }
    }

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

        }
    }
}

Answer 1

You already called getLastSignedInAccount method in onStart() callback method. So, When you successfully log in with your gmail account,after each time you came into this activity, it does not show account choose dialog. So, No worries about this.

You can log out your user by following code. then you will get same log in pattern what you get first time.

    private void signOut() {

    mGoogleSignInClient.signOut()
            .addOnCompleteListener(this, new OnCompleteListener<Void>() {
                @Override
                public void onComplete(@NonNull Task<Void> task) {
                    // ...
                }
            });
}