Safeguarding against runtime exceptions when importing and exporting

app/src/main/java/acr/browser/lightning/fragment/BookmarkSettingsFragment.java

@@ -24,6 +24,7 @@ import android.widget.ArrayAdapter;
 
 import com.anthonycr.bonsai.CompletableOnSubscribe;
 import com.anthonycr.bonsai.SingleOnSubscribe;
+import com.anthonycr.bonsai.Subscription;
 import com.anthonycr.grant.PermissionsManager;
 import com.anthonycr.grant.PermissionsResultAction;
 
@@ -48,6 +49,7 @@ import com.anthonycr.bonsai.Schedulers;
 import acr.browser.lightning.database.bookmark.BookmarkModel;
 import acr.browser.lightning.dialog.BrowserDialog;
 import acr.browser.lightning.utils.Preconditions;
+import acr.browser.lightning.utils.SubscriptionUtils;
 import acr.browser.lightning.utils.Utils;
 
 public class BookmarkSettingsFragment extends PreferenceFragment implements Preference.OnPreferenceClickListener {
@@ -66,8 +68,12 @@ public class BookmarkSettingsFragment extends PreferenceFragment implements Pref
 
     private File[] mFileList;
     private String[] mFileNameList;
+
     @Nullable private BookmarkLocalSync mSync;
 
+    @Nullable private Subscription mImportSubscription;
+    @Nullable private Subscription mExportSubscription;
+
     private static final String[] REQUIRED_PERMISSIONS = new String[]{
         Manifest.permission.READ_EXTERNAL_STORAGE,
         Manifest.permission.WRITE_EXTERNAL_STORAGE
@@ -153,9 +159,21 @@ public class BookmarkSettingsFragment extends PreferenceFragment implements Pref
         }
     }
 
+    @Override
+    public void onDestroyView() {
+        super.onDestroyView();
+
+        SubscriptionUtils.safeUnsubscribe(mExportSubscription);
+        SubscriptionUtils.safeUnsubscribe(mImportSubscription);
+    }
+
     @Override
     public void onDestroy() {
         super.onDestroy();
+
+        SubscriptionUtils.safeUnsubscribe(mExportSubscription);
+        SubscriptionUtils.safeUnsubscribe(mImportSubscription);
+
         mActivity = null;
     }
 
@@ -197,14 +215,21 @@ public class BookmarkSettingsFragment extends PreferenceFragment implements Pref
                                 .subscribe(new SingleOnSubscribe<List<HistoryItem>>() {
                                     @Override
                                     public void onItem(@Nullable List<HistoryItem> item) {
+                                        if (!isAdded()) {
+                                            return;
+                                        }
+
                                         Preconditions.checkNonNull(item);
                                         final File exportFile = BookmarkExporter.createNewExportFile();
-                                        BookmarkExporter.exportBookmarksToFile(item, exportFile)
+                                        SubscriptionUtils.safeUnsubscribe(mExportSubscription);
+                                        mExportSubscription = BookmarkExporter.exportBookmarksToFile(item, exportFile)
                                             .subscribeOn(Schedulers.io())
                                             .observeOn(Schedulers.main())
                                             .subscribe(new CompletableOnSubscribe() {
                                                 @Override
                                                 public void onComplete() {
+                                                    mExportSubscription = null;
+
                                                     Activity activity = getActivity();
                                                     if (activity != null) {
                                                         Utils.showSnackbar(activity, activity.getString(R.string.bookmark_export_path)
@@ -214,9 +239,11 @@ public class BookmarkSettingsFragment extends PreferenceFragment implements Pref
 
                                                 @Override
                                                 public void onError(@NonNull Throwable throwable) {
+                                                    mExportSubscription = null;
+
                                                     Log.e(TAG, "onError: exporting bookmarks", throwable);
                                                     Activity activity = getActivity();
-                                                    if (activity != null) {
+                                                    if (activity != null && !activity.isFinishing() && isAdded()) {
                                                         Utils.createInformativeDialog(activity, R.string.title_error, R.string.bookmark_export_failure);
                                                     } else {
                                                         Utils.showToast(mApplication, R.string.bookmark_export_failure);
@@ -229,7 +256,12 @@ public class BookmarkSettingsFragment extends PreferenceFragment implements Pref
 
                         @Override
                         public void onDenied(String permission) {
-                            //TODO Show message
+                            Activity activity = getActivity();
+                            if (activity != null && !activity.isFinishing() && isAdded()) {
+                                Utils.createInformativeDialog(activity, R.string.title_error, R.string.bookmark_export_failure);
+                            } else {
+                                Utils.showToast(mApplication, R.string.bookmark_export_failure);
+                            }
                         }
                     });
                 return true;
@@ -445,11 +477,14 @@ public class BookmarkSettingsFragment extends PreferenceFragment implements Pref
                     Dialog dialog1 = builder.show();
                     BrowserDialog.setDialogSize(mActivity, dialog1);
                 } else {
-                    BookmarkExporter.importBookmarksFromFile(mFileList[which])
+                    SubscriptionUtils.safeUnsubscribe(mImportSubscription);
+                    mImportSubscription = BookmarkExporter.importBookmarksFromFile(mFileList[which])
                         .subscribeOn(Schedulers.io())
                         .subscribe(new SingleOnSubscribe<List<HistoryItem>>() {
                             @Override
                             public void onItem(@Nullable final List<HistoryItem> importList) {
+                                mImportSubscription = null;
+
                                 Preconditions.checkNonNull(importList);
                                 mBookmarkManager.addBookmarkList(importList)
                                     .observeOn(Schedulers.main())
@@ -467,9 +502,11 @@ public class BookmarkSettingsFragment extends PreferenceFragment implements Pref
 
                             @Override
                             public void onError(@NonNull Throwable throwable) {
+                                mImportSubscription = null;
+
                                 Log.e(TAG, "onError: importing bookmarks", throwable);
                                 Activity activity = getActivity();
-                                if (activity != null) {
+                                if (activity != null && !activity.isFinishing() && isAdded()) {
                                     Utils.createInformativeDialog(activity, R.string.title_error, R.string.import_bookmark_error);
                                 } else {
                                     Utils.showToast(mApplication, R.string.import_bookmark_error);