Create ActivitySourceRetrievalListener (#867)

Correctly handle Activity weak references in `AddSourceActivity`

Author: mshafrir-stripe

stripe/src/main/java/com/stripe/android/CustomerSession.java

@@ -1,5 +1,6 @@
 package com.stripe.android;
 
+import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
@@ -17,6 +18,7 @@
 import com.stripe.android.model.ShippingInformation;
 import com.stripe.android.model.Source;
 
+import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Calendar;
@@ -776,6 +778,24 @@ void onError(int errorCode, @Nullable String errorMessage,
                      @Nullable StripeError stripeError);
     }
 
+    /**
+     * Abstract implementation of {@link SourceRetrievalListener} that holds a
+     * {@link WeakReference} to an {@link Activity} object.
+     */
+    public abstract static class ActivitySourceRetrievalListener<A extends Activity>
+            implements SourceRetrievalListener {
+        @NonNull private final WeakReference<A> mActivityRef;
+
+        public ActivitySourceRetrievalListener(@NonNull A activity) {
+            this.mActivityRef = new WeakReference<>(activity);
+        }
+
+        @Nullable
+        protected A getActivity() {
+            return mActivityRef.get();
+        }
+    }
+
     private static class CustomerMessage {
         @Nullable private final String operationId;
         @Nullable private final Customer customer;

stripe/src/main/java/com/stripe/android/view/AddSourceActivity.java

@@ -10,7 +10,6 @@
 import android.view.KeyEvent;
 import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputMethodManager;
-import android.widget.FrameLayout;
 import android.widget.TextView;
 
 import com.stripe.android.ActivitySourceCallback;
@@ -42,7 +41,6 @@ public class AddSourceActivity extends StripeActivity {
 
     @Nullable private CardMultilineWidget mCardMultilineWidget;
     @Nullable private CustomerSessionProxy mCustomerSessionProxy;
-    private FrameLayout mErrorLayout;
     @Nullable private StripeProvider mStripeProvider;
 
     private boolean mStartedFromPaymentSession;
@@ -90,8 +88,7 @@ protected void onCreate(Bundle savedInstanceState) {
         mViewStub.inflate();
         mCardMultilineWidget = findViewById(R.id.add_source_card_entry_widget);
         initEnterListeners();
-        mErrorLayout = findViewById(R.id.add_source_error_container);
-        boolean showZip = getIntent().getBooleanExtra(EXTRA_SHOW_ZIP, false);
+        final boolean showZip = getIntent().getBooleanExtra(EXTRA_SHOW_ZIP, false);
         mUpdatesCustomer = getIntent().getBooleanExtra(EXTRA_UPDATE_CUSTOMER, false);
         mStartedFromPaymentSession =
                 getIntent().getBooleanExtra(EXTRA_PAYMENT_SESSION_ACTIVE, true);
@@ -123,7 +120,7 @@ void initCustomerSessionTokens() {
 
     @Override
     protected void onActionSave() {
-        final Card card = mCardMultilineWidget.getCard();
+        final Card card = mCardMultilineWidget != null ? mCardMultilineWidget.getCard() : null;
         if (card == null) {
             // In this case, the error will be displayed on the card widget itself.
             return;
@@ -142,20 +139,7 @@ protected void onActionSave() {
 
     private void attachCardToCustomer(@NonNull final StripePaymentSource source) {
         final CustomerSession.SourceRetrievalListener listener =
-                new CustomerSession.SourceRetrievalListener() {
-                    @Override
-                    public void onSourceRetrieved(@NonNull Source source) {
-                        finishWithSource(source);
-                    }
-
-                    @Override
-                    public void onError(int errorCode, @Nullable String errorMessage,
-                                        @Nullable StripeError stripeError) {
-                        // No need to show this error, because it will be broadcast
-                        // from the CustomerSession
-                        setCommunicatingProgress(false);
-                    }
-                };
+                new SourceRetrievalListenerImpl(this);
 
         if (mCustomerSessionProxy == null) {
             @Source.SourceType final String sourceType;
@@ -277,4 +261,34 @@ public void onSuccess(@NonNull Source source) {
             }
         }
     }
+
+    private static final class SourceRetrievalListenerImpl
+            extends CustomerSession.ActivitySourceRetrievalListener<AddSourceActivity> {
+        private SourceRetrievalListenerImpl(@NonNull AddSourceActivity activity) {
+            super(activity);
+        }
+
+        @Override
+        public void onSourceRetrieved(@NonNull Source source) {
+            final AddSourceActivity activity = getActivity();
+            if (activity == null) {
+                return;
+            }
+
+            activity.finishWithSource(source);
+        }
+
+        @Override
+        public void onError(int errorCode, @Nullable String errorMessage,
+                            @Nullable StripeError stripeError) {
+            final AddSourceActivity activity = getActivity();
+            if (activity == null) {
+                return;
+            }
+
+            // No need to show this error, because it will be broadcast
+            // from the CustomerSession
+            activity.setCommunicatingProgress(false);
+        }
+    }
 }