Adds confirmation when going up from the edit monster screen to save, cancel, or discard changes.

app/src/main/java/com/majinnaibu/monstercards/MainActivity.java

@@ -1,10 +1,11 @@
 package com.majinnaibu.monstercards;
 
 import android.os.Bundle;
+import android.view.MenuItem;
 
+import androidx.annotation.NonNull;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.navigation.NavController;
-import androidx.navigation.Navigation;
 import androidx.navigation.fragment.NavHostFragment;
 import androidx.navigation.ui.AppBarConfiguration;
 import androidx.navigation.ui.NavigationUI;
@@ -12,13 +13,19 @@ import androidx.navigation.ui.NavigationUI;
 import com.google.android.material.bottomnavigation.BottomNavigationView;
 import com.majinnaibu.monstercards.init.AppCenterInitializer;
 import com.majinnaibu.monstercards.init.FlipperInitializer;
+import com.majinnaibu.monstercards.utils.Logger;
 
 public class MainActivity extends AppCompatActivity {
 
     @Override
-    public boolean onSupportNavigateUp() {
+    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
-        NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
+        if (item.getItemId() == android.R.id.home) {
-        return navController.navigateUp() || super.onSupportNavigateUp();
+            Logger.logDebug("Home selected (in MainActivity)");
+            getOnBackPressedDispatcher().onBackPressed();
+            return true;
+        }
+
+        return super.onOptionsItemSelected(item);
     }
 
     @SuppressWarnings("ConstantConditions")
@@ -44,5 +51,4 @@ public class MainActivity extends AppCompatActivity {
         NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration);
         NavigationUI.setupWithNavController(navView, navController);
     }
-
 }

app/src/main/java/com/majinnaibu/monstercards/data/MonsterDAO.java

@@ -4,6 +4,7 @@ package com.majinnaibu.monstercards.data;
 import androidx.room.Dao;
 import androidx.room.Delete;
 import androidx.room.Insert;
+import androidx.room.OnConflictStrategy;
 import androidx.room.Query;
 
 import com.majinnaibu.monstercards.models.Monster;
@@ -30,6 +31,9 @@ public interface MonsterDAO {
     @Insert
     Completable insertAll(Monster... monsters);
 
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    Completable save(Monster... monsters);
+
     @Delete
     Completable delete(Monster monster);
 }

app/src/main/java/com/majinnaibu/monstercards/data/MonsterRepository.java

@@ -63,4 +63,9 @@ public class MonsterRepository {
         return result;
     }
 
+    public Completable saveMonster(Monster monster) {
+        Completable result = m_db.monsterDAO().save(monster);
+        result.subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread());
+        return result;
+    }
 }

app/src/main/java/com/majinnaibu/monstercards/ui/editmonster/EditMonsterFragment.java

@@ -6,14 +6,17 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.TextView;
 
+import androidx.activity.OnBackPressedCallback;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.appcompat.app.AlertDialog;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.navigation.NavBackStackEntry;
 import androidx.navigation.NavController;
 import androidx.navigation.NavDirections;
 import androidx.navigation.Navigation;
 
+import com.google.android.material.snackbar.Snackbar;
 import com.majinnaibu.monstercards.R;
 import com.majinnaibu.monstercards.data.MonsterRepository;
 import com.majinnaibu.monstercards.models.Monster;
@@ -21,19 +24,20 @@ import com.majinnaibu.monstercards.ui.MCFragment;
 import com.majinnaibu.monstercards.ui.monster.MonsterDetailFragmentArgs;
 import com.majinnaibu.monstercards.utils.Logger;
 
+import java.util.Objects;
 import java.util.UUID;
 
+import io.reactivex.rxjava3.android.schedulers.AndroidSchedulers;
+import io.reactivex.rxjava3.observers.DisposableCompletableObserver;
 import io.reactivex.rxjava3.observers.DisposableSingleObserver;
+import io.reactivex.rxjava3.schedulers.Schedulers;
 
+@SuppressWarnings("FieldCanBeLocal")
 public class EditMonsterFragment extends MCFragment {
 
     private EditMonsterViewModel mViewModel;
     private ViewHolder mHolder;
 
-    public static EditMonsterFragment newInstance() {
-        return new EditMonsterFragment();
-    }
-
     @Override
     public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
                              @Nullable Bundle savedInstanceState) {
@@ -49,20 +53,20 @@ public class EditMonsterFragment extends MCFragment {
 
         View root = inflater.inflate(R.layout.fragment_edit_monster, container, false);
         mHolder = new ViewHolder(root);
-        requireAppCompatActivity().getSupportActionBar().setTitle(getString(R.string.title_edit_monster, getString(R.string.default_monster_name)));
+
+        setTitle(getString(R.string.title_edit_monster, getString(R.string.default_monster_name)));
 
         // TODO: Show a loading spinner until we have the monster loaded.
-        if (mViewModel.hasError() || !mViewModel.hasLoaded() || !mViewModel.getMonsterId().getValue().equals(monsterId)) {
+        if (mViewModel.hasError() || !mViewModel.hasLoaded() || !Objects.equals(mViewModel.getMonsterId().getValue(), monsterId)) {
             repository.getMonster(monsterId).toObservable()
                     .firstOrError()
                     .subscribe(new DisposableSingleObserver<Monster>() {
                         @Override
                         public void onSuccess(@io.reactivex.rxjava3.annotations.NonNull Monster monster) {
-                            Logger.logDebug(String.format("Monster loaded: %s", monster.name));
                             mViewModel.setHasLoaded(true);
                             mViewModel.setHasError(false);
                             mViewModel.copyFromMonster(monster);
-                            requireAppCompatActivity().getSupportActionBar().setTitle(getString(R.string.title_edit_monster, monster.name));
+                            setTitle(getString(R.string.title_edit_monster, monster.name));
                             dispose();
                         }
 
@@ -77,20 +81,57 @@ public class EditMonsterFragment extends MCFragment {
                     });
         }
         mHolder.basicInfoButton.setOnClickListener(v -> {
-            // TODO: Navigate to the EditBasicInfo fragment
-            Logger.logDebug("Basic Info clicked");
             NavDirections action = EditMonsterFragmentDirections.actionEditMonsterFragmentToEditBasicInfoFragment();
             View view = getView();
             assert view != null;
             Navigation.findNavController(view).navigate(action);
         });
 
-        return root;
+        requireActivity().getOnBackPressedDispatcher().addCallback(getViewLifecycleOwner(), new OnBackPressedCallback(true) {
+            @Override
+            public void handleOnBackPressed() {
+                if (mViewModel.hasChanges()) {
+                    View view = getView();
+                    AlertDialog alertDialog = new AlertDialog.Builder(requireContext()).create();
+                    alertDialog.setTitle("Unsaved Changes");
+                    alertDialog.setMessage("Do you want to save your changes?");
+                    alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "Save", (dialog, id) -> {
+                        // Save the monster. Navigate up if the save is successful. Show a SnackBar if there was an error.
+                        getMonsterRepository().saveMonster(mViewModel.buildMonster())
+                                .subscribeOn(Schedulers.io())
+                                .observeOn(AndroidSchedulers.mainThread())
+                                .subscribe(
+                                        new DisposableCompletableObserver() {
+                                            @Override
+                                            public void onComplete() {
+                                                Navigation.findNavController(requireView()).navigateUp();
                                             }
 
                                             @Override
-    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
+                                            public void onError(@io.reactivex.rxjava3.annotations.NonNull Throwable e) {
-        super.onActivityCreated(savedInstanceState);
+                                                Logger.logError("Error creating monster", e);
+                                                assert view != null;
+                                                Snackbar.make(view, getString(R.string.snackbar_failed_to_create_monster), Snackbar.LENGTH_LONG)
+                                                        .setAction("Action", null).show();
+                                            }
+                                        });
+                    });
+                    alertDialog.setButton(AlertDialog.BUTTON_NEGATIVE, "Discard", (dialog, id) -> {
+                        // Navigate up ignoring unsaved changes.
+                        Navigation.findNavController(requireView()).navigateUp();
+                    });
+                    alertDialog.setButton(AlertDialog.BUTTON_NEUTRAL, "Cancel", (dialog, id) -> {
+                        // Do nothing.
+                    });
+                    alertDialog.show();
+                } else {
+                    // No changes so we can safely leave.
+                    Navigation.findNavController(requireView()).navigateUp();
+                }
+            }
+        });
+
+        return root;
     }
 
     private static class ViewHolder {

app/src/main/java/com/majinnaibu/monstercards/ui/editmonster/EditMonsterViewModel.java

@@ -9,6 +9,7 @@ import com.majinnaibu.monstercards.models.Monster;
 
 import java.util.UUID;
 
+@SuppressWarnings({"ConstantConditions", "unused"})
 public class EditMonsterViewModel extends ViewModel {
     private final MutableLiveData<String> mName;
     private final MutableLiveData<UUID> mMonsterId;
@@ -20,6 +21,7 @@ public class EditMonsterViewModel extends ViewModel {
     private final MutableLiveData<String> mSubtype;
     private final MutableLiveData<String> mAlignment;
     private final MutableLiveData<String> mCustomHitPoints;
+    private final MutableLiveData<Boolean> mHasChanges;
 
     public EditMonsterViewModel() {
 
@@ -33,6 +35,8 @@ public class EditMonsterViewModel extends ViewModel {
         mSubtype = new MutableLiveData<>("");
         mAlignment = new MutableLiveData<>("");
         mCustomHitPoints = new MutableLiveData<>("");
+        // TODO: consider initializing this to true so all new monsters need saving
+        mHasChanges = new MutableLiveData<>(false);
     }
 
     public void copyFromMonster(Monster monster) {
@@ -44,6 +48,7 @@ public class EditMonsterViewModel extends ViewModel {
         mSubtype.setValue(monster.subtype);
         mAlignment.setValue(monster.alignment);
         mCustomHitPoints.setValue(monster.customHPDescription);
+        mHasChanges.setValue(false);
     }
 
     public LiveData<String> getName() {
@@ -52,9 +57,9 @@ public class EditMonsterViewModel extends ViewModel {
 
     public void setName(@NonNull String name) {
         mName.setValue(name);
+        mHasChanges.setValue(true);
     }
 
-
     public LiveData<UUID> getMonsterId() {
         return mMonsterId;
     }
@@ -97,6 +102,7 @@ public class EditMonsterViewModel extends ViewModel {
 
     public void setSize(@NonNull String size) {
         mSize.setValue(size);
+        mHasChanges.setValue(true);
     }
 
     public LiveData<String> getType() {
@@ -105,6 +111,7 @@ public class EditMonsterViewModel extends ViewModel {
 
     public void setType(@NonNull String type) {
         mType.setValue(type);
+        mHasChanges.setValue(true);
     }
 
     public LiveData<String> getSubtype() {
@@ -113,6 +120,7 @@ public class EditMonsterViewModel extends ViewModel {
 
     public void setSubtype(@NonNull String subType) {
         mSubtype.setValue(subType);
+        mHasChanges.setValue(true);
     }
 
     public LiveData<String> getAlignment() {
@@ -121,6 +129,7 @@ public class EditMonsterViewModel extends ViewModel {
 
     public void setAlignment(@NonNull String alignment) {
         mAlignment.setValue(alignment);
+        mHasChanges.setValue(true);
     }
 
     public LiveData<String> getCustomHitPoints() {
@@ -129,5 +138,32 @@ public class EditMonsterViewModel extends ViewModel {
 
     public void setCustomHitPoints(String customHitPoints) {
         mCustomHitPoints.setValue(customHitPoints);
+        mHasChanges.setValue(true);
+    }
+
+    public LiveData<Boolean> getHasChanges() {
+        return mHasChanges;
+    }
+
+    public void setHasChanges(@NonNull Boolean hasChanges) {
+        mHasChanges.setValue(hasChanges);
+    }
+
+    public boolean hasChanges() {
+        return mHasChanges.getValue();
+    }
+
+    public Monster buildMonster() {
+        Monster monster = new Monster();
+
+        monster.id = mMonsterId.getValue();
+        monster.name = mName.getValue();
+        monster.size = mSize.getValue();
+        monster.type = mType.getValue();
+        monster.subtype = mSubtype.getValue();
+        monster.alignment = mAlignment.getValue();
+        monster.customHPDescription = mCustomHitPoints.getValue();
+
+        return monster;
     }
 }