Fix memory leaks in example app (#865)

**Summary**
- Create `ActivitySourceCallback` to help with memory
  handling
- Refactor and clean-up classes in example app to fix
  memory leaks as identified by LeakCanary
- Call `CompositeSubscription#unsubscribe()` in
  `Activity#onDestroy()` where missing

**Motivation**
ANDROID-349

**Testing**
Ran example app

example/src/main/java/com/stripe/example/activity/CustomerSessionActivity.java

@@ -50,7 +50,7 @@ protected void onCreate(Bundle savedInstanceState) {
                         @Override
                         public void onStringResponse(String string) {
                             if (string.startsWith("Error: ")) {
-                                mErrorDialogHandler.showError(string);
+                                mErrorDialogHandler.show(string);
                             }
                         }
                     }));
@@ -68,7 +68,7 @@ public void onCustomerRetrieved(@NonNull Customer customer) {
                     public void onError(int httpCode, @Nullable String errorMessage,
                                         @Nullable StripeError stripeError) {
                         mSelectSourceButton.setEnabled(false);
-                        mErrorDialogHandler.showError(errorMessage);
+                        mErrorDialogHandler.show(errorMessage);
                         mProgressBar.setVisibility(View.INVISIBLE);
                     }
                 });

example/src/main/java/com/stripe/example/activity/PaymentIntentActivity.java

@@ -45,9 +45,11 @@ public class PaymentIntentActivity extends AppCompatActivity {
     private static final String TAG = PaymentIntentActivity.class.getName();
 
     private static final String RETURN_URL = "stripe://payment_intent_return";
+
+    @NonNull private final CompositeSubscription mCompositeSubscription =
+            new CompositeSubscription();
     private ProgressDialogController mProgressDialogController;
     private ErrorDialogHandler mErrorDialogHandler;
-    private CompositeSubscription mCompositeSubscription;
     private Stripe mStripe;
     private StripeService mStripeService;
     private String mClientSecret;
@@ -60,16 +62,15 @@ public class PaymentIntentActivity extends AppCompatActivity {
     protected void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_payment_intent_demo);
-        Button createPaymentIntent = findViewById(R.id.btn_create_payment_intent);
+        final Button createPaymentIntent = findViewById(R.id.btn_create_payment_intent);
         mRetrievePaymentIntent = findViewById(R.id.btn_retrieve_payment_intent);
         mConfirmPaymentIntent = findViewById(R.id.btn_confirm_payment_intent);
         mPaymentIntentValue = findViewById(R.id.payment_intent_value);
         mCardInputWidget = findViewById(R.id.card_input_widget);
-        mProgressDialogController =
-                new ProgressDialogController(getSupportFragmentManager());
 
+        mProgressDialogController = new ProgressDialogController(getSupportFragmentManager(),
+                getResources());
         mErrorDialogHandler = new ErrorDialogHandler(getSupportFragmentManager());
-        mCompositeSubscription = new CompositeSubscription();
         mStripe = new Stripe(getApplicationContext());
         Retrofit retrofit = RetrofitFactory.getInstance();
         mStripeService = retrofit.create(StripeService.class);
@@ -98,6 +99,13 @@ public void onClick(View v) {
         });
     }
 
+    @Override
+    protected void onDestroy() {
+        mCompositeSubscription.unsubscribe();
+        super.onDestroy();
+    }
+
+    @NonNull
     private Map<String, Object> createPaymentIntentParams() {
         final Map<String, Object> params = new HashMap<>();
         params.put("allowed_source_types[]", "card");
@@ -113,14 +121,13 @@ void createPaymentIntent() {
                 .doOnSubscribe(new Action0() {
                     @Override
                     public void call() {
-                        mProgressDialogController.setMessageResource(R.string.creating_payment_intent);
-                        mProgressDialogController.startProgress();
+                        mProgressDialogController.show(R.string.creating_payment_intent);
                     }
                 })
                 .doOnUnsubscribe(new Action0() {
                     @Override
                     public void call() {
-                        mProgressDialogController.finishProgress();
+                        mProgressDialogController.dismiss();
                     }
                 })
                 .subscribe(
@@ -143,7 +150,7 @@ public void call(ResponseBody responseBody) {
                         new Action1<Throwable>() {
                             @Override
                             public void call(Throwable throwable) {
-                                mErrorDialogHandler.showError(throwable.getLocalizedMessage());
+                                mErrorDialogHandler.show(throwable.getLocalizedMessage());
                             }
                         }
                 );
@@ -165,14 +172,13 @@ public PaymentIntent call() throws Exception {
                 .doOnSubscribe(new Action0() {
                     @Override
                     public void call() {
-                        mProgressDialogController.setMessageResource(R.string.retrieving_payment_intent);
-                        mProgressDialogController.startProgress();
+                        mProgressDialogController.show(R.string.retrieving_payment_intent);
                     }
                 })
                 .doOnUnsubscribe(new Action0() {
                     @Override
                     public void call() {
-                        mProgressDialogController.finishProgress();
+                        mProgressDialogController.dismiss();
                     }
                 })
                 .observeOn(AndroidSchedulers.mainThread()).subscribe(
@@ -216,14 +222,13 @@ public PaymentIntent call() throws Exception {
                 .doOnSubscribe(new Action0() {
                     @Override
                     public void call() {
-                        mProgressDialogController.setMessageResource(R.string.confirming_payment_intent);
-                        mProgressDialogController.startProgress();
+                        mProgressDialogController.show(R.string.confirming_payment_intent);
                     }
                 })
                 .doOnUnsubscribe(new Action0() {
                     @Override
                     public void call() {
-                        mProgressDialogController.finishProgress();
+                        mProgressDialogController.dismiss();
                     }
                 })
                 .subscribe(

example/src/main/java/com/stripe/example/activity/PaymentMultilineActivity.java

@@ -1,6 +1,7 @@
 package com.stripe.example.activity;
 
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.v7.app.AppCompatActivity;
 import android.widget.ListView;
@@ -37,7 +38,9 @@ public class PaymentMultilineActivity extends AppCompatActivity {
     ErrorDialogHandler mErrorDialogHandler;
 
     CardMultilineWidget mCardMultilineWidget;
-    CompositeSubscription mCompositeSubscription;
+
+    @NonNull private final CompositeSubscription mCompositeSubscription =
+            new CompositeSubscription();
 
     private SimpleAdapter mSimpleAdapter;
     private List<Map<String, String>> mCardSources= new ArrayList<>();
@@ -47,11 +50,10 @@ protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_payment_multiline);
 
-        mCompositeSubscription = new CompositeSubscription();
         mCardMultilineWidget = findViewById(R.id.card_multiline_widget);
 
-        mProgressDialogController =
-                new ProgressDialogController(getSupportFragmentManager());
+        mProgressDialogController = new ProgressDialogController(getSupportFragmentManager(),
+                getResources());
 
         mErrorDialogHandler = new ErrorDialogHandler(getSupportFragmentManager());
 
@@ -100,14 +102,14 @@ public Source call() throws Exception {
                         new Action0() {
                             @Override
                             public void call() {
-                                mProgressDialogController.startProgress();
+                                mProgressDialogController.show(R.string.progressMessage);
                             }
                         })
                 .doOnUnsubscribe(
                         new Action0() {
                             @Override
                             public void call() {
-                                mProgressDialogController.finishProgress();
+                                mProgressDialogController.dismiss();
                             }
                         })
                 .subscribe(
@@ -120,7 +122,7 @@ public void call(Source source) {
                         new Action1<Throwable>() {
                             @Override
                             public void call(Throwable throwable) {
-                                mErrorDialogHandler.showError(throwable.getLocalizedMessage());
+                                mErrorDialogHandler.show(throwable.getLocalizedMessage());
                             }
                         }));
     }
@@ -139,4 +141,9 @@ private void addToList(@Nullable Source source) {
         mSimpleAdapter.notifyDataSetChanged();
     }
 
+    @Override
+    protected void onDestroy() {
+        mCompositeSubscription.unsubscribe();
+        super.onDestroy();
+    }
 }

example/src/main/java/com/stripe/example/activity/PaymentSessionActivity.java

@@ -123,7 +123,7 @@ private void setupCustomerSession() {
                             @Override
                             public void onStringResponse(String string) {
                                 if (string.startsWith("Error: ")) {
-                                    mErrorDialogHandler.showError(string);
+                                    mErrorDialogHandler.show(string);
                                 }
                             }
                         }));
@@ -142,7 +142,7 @@ public void onError(int httpCode, @Nullable String errorMessage,
                         mCustomer = null;
                         mSelectPaymentButton.setEnabled(false);
                         mSelectShippingButton.setEnabled(false);
-                        mErrorDialogHandler.showError(errorMessage);
+                        mErrorDialogHandler.show(errorMessage);
                         mProgressBar.setVisibility(View.INVISIBLE);
                     }
                 });
@@ -287,7 +287,7 @@ public void onError(int errorCode, @Nullable String errorMessage) {
                 return;
             }
 
-            activity.mErrorDialogHandler.showError(errorMessage);
+            activity.mErrorDialogHandler.show(errorMessage);
         }
 
         @Override

example/src/main/java/com/stripe/example/activity/RedirectActivity.java

@@ -44,8 +44,10 @@ public class RedirectActivity extends AppCompatActivity {
     private static final String QUERY_CLIENT_SECRET = "client_secret";
     private static final String QUERY_SOURCE_ID = "source";
 
+    @NonNull private final CompositeSubscription mCompositeSubscription =
+            new CompositeSubscription();
+
     private CardInputWidget mCardInputWidget;
-    private CompositeSubscription mCompositeSubscription;
     private RedirectAdapter mRedirectAdapter;
     private ErrorDialogHandler mErrorDialogHandler;
     private RedirectDialogController mRedirectDialogController;
@@ -58,10 +60,10 @@ protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_polling);
 
-        mCompositeSubscription = new CompositeSubscription();
         mCardInputWidget = findViewById(R.id.card_widget_three_d);
         mErrorDialogHandler = new ErrorDialogHandler(this.getSupportFragmentManager());
-        mProgressDialogController = new ProgressDialogController(this.getSupportFragmentManager());
+        mProgressDialogController = new ProgressDialogController(this.getSupportFragmentManager(),
+                getResources());
         mRedirectDialogController = new RedirectDialogController(this);
         mStripe = new Stripe(getApplicationContext());
 
@@ -113,8 +115,8 @@ protected void onNewIntent(Intent intent) {
 
     @Override
     protected void onDestroy() {
-        super.onDestroy();
         mCompositeSubscription.unsubscribe();
+        super.onDestroy();
     }
 
     void beginSequence() {
@@ -149,8 +151,7 @@ public Source call() throws Exception {
                 .doOnSubscribe(new Action0() {
                     @Override
                     public void call() {
-                        mProgressDialogController.setMessageResource(R.string.createSource);
-                        mProgressDialogController.startProgress();
+                        mProgressDialogController.show(R.string.createSource);
                     }
                 })
                 .subscribe(
@@ -176,15 +177,15 @@ public void call(Source source) {
                                     // The card Source can be used to create a 3DS Source
                                     createThreeDSecureSource(source.getId());
                                 } else {
-                                    mProgressDialogController.finishProgress();
+                                    mProgressDialogController.dismiss();
                                 }
 
                             }
                         },
                         new Action1<Throwable>() {
                             @Override
                             public void call(Throwable throwable) {
-                                mErrorDialogHandler.showError(throwable.getMessage());
+                                mErrorDialogHandler.show(throwable.getMessage());
                             }
                         }
                 ));
@@ -221,7 +222,7 @@ public Source call() throws Exception {
                 .doOnUnsubscribe(new Action0() {
                     @Override
                     public void call() {
-                        mProgressDialogController.finishProgress();
+                        mProgressDialogController.dismiss();
                     }
                 })
                 .subscribe(
@@ -238,7 +239,7 @@ public void call(Source source) {
                         new Action1<Throwable>() {
                             @Override
                             public void call(Throwable throwable) {
-                                mErrorDialogHandler.showError(throwable.getMessage());
+                                mErrorDialogHandler.show(throwable.getMessage());
                             }
                         }
                 ));

example/src/main/java/com/stripe/example/controller/AsyncTaskTokenController.java

@@ -12,6 +12,7 @@
 import com.stripe.android.model.Card;
 import com.stripe.android.model.Token;
 import com.stripe.android.view.CardInputWidget;
+import com.stripe.example.R;
 
 /**
  * Logic needed to create tokens using the {@link android.os.AsyncTask} methods included in the
@@ -21,7 +22,6 @@ public class AsyncTaskTokenController {
 
     @NonNull private final Stripe mStripe;
     @NonNull private final ErrorDialogHandler mErrorDialogHandler;
-    @NonNull private final ListViewController mOutputListController;
     @NonNull private final ProgressDialogController mProgressDialogController;
 
     @Nullable private CardInputWidget mCardInputWidget;
@@ -30,19 +30,22 @@ public AsyncTaskTokenController(
             @NonNull Button button,
             @NonNull CardInputWidget cardInputWidget,
             @NonNull Context context,
-            @NonNull ErrorDialogHandler errorDialogHandler,
-            @NonNull ListViewController outputListController,
-            @NonNull ProgressDialogController progressDialogController) {
+            @NonNull final ErrorDialogHandler errorDialogHandler,
+            @NonNull final ListViewController outputListController,
+            @NonNull final ProgressDialogController progressDialogController) {
         mCardInputWidget = cardInputWidget;
         mStripe = new Stripe(context);
         mErrorDialogHandler = errorDialogHandler;
         mProgressDialogController = progressDialogController;
-        mOutputListController = outputListController;
 
         button.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View view) {
-                saveCard();
+                saveCard(new TokenCallbackImpl(
+                        errorDialogHandler,
+                        outputListController,
+                        progressDialogController
+                ));
             }
         });
     }
@@ -51,25 +54,39 @@ public void detach() {
         mCardInputWidget = null;
     }
 
-    private void saveCard() {
-        final Card cardToSave = mCardInputWidget.getCard();
+    private void saveCard(@NonNull TokenCallback tokenCallback) {
+        final Card cardToSave = mCardInputWidget != null ? mCardInputWidget.getCard() : null;
         if (cardToSave == null) {
-            mErrorDialogHandler.showError("Invalid Card Data");
+            mErrorDialogHandler.show("Invalid Card Data");
             return;
         }
-        mProgressDialogController.startProgress();
+        mProgressDialogController.show(R.string.progressMessage);
         mStripe.createToken(
                 cardToSave,
                 PaymentConfiguration.getInstance().getPublishableKey(),
-                new TokenCallback() {
-                    public void onSuccess(@NonNull Token token) {
-                        mOutputListController.addToList(token);
-                        mProgressDialogController.finishProgress();
-                    }
-                    public void onError(@NonNull Exception error) {
-                        mErrorDialogHandler.showError(error.getLocalizedMessage());
-                        mProgressDialogController.finishProgress();
-                    }
-                });
+                tokenCallback);
+    }
+
+    private static class TokenCallbackImpl implements TokenCallback {
+        @NonNull private final ErrorDialogHandler mErrorDialogHandler;
+        @NonNull private final ListViewController mOutputListController;
+        @NonNull private final ProgressDialogController mProgressDialogController;
+
+        private TokenCallbackImpl(@NonNull ErrorDialogHandler errorDialogHandler,
+                                 @NonNull ListViewController outputListController,
+                                 @NonNull ProgressDialogController progressDialogController) {
+            this.mErrorDialogHandler = errorDialogHandler;
+            this.mOutputListController = outputListController;
+            this.mProgressDialogController = progressDialogController;
+        }
+
+        public void onSuccess(@NonNull Token token) {
+            mOutputListController.addToList(token);
+            mProgressDialogController.dismiss();
+        }
+        public void onError(@NonNull Exception error) {
+            mErrorDialogHandler.show(error.getLocalizedMessage());
+            mProgressDialogController.dismiss();
+        }
     }
 }