Fix crashes when no list is available

app/src/main/java/com/woefe/shoppinglist/activity/MainActivity.java

@@ -173,8 +173,13 @@ public boolean onCreateOptionsMenu(Menu menu) {
     }
 
     private void doShare() {
-        ShoppingList list = getBinder().getList(currentListName);
         String text;
+        ShoppingList list = getBinder().getList(currentListName);
+
+        if (list == null) {
+            Toast.makeText(this, R.string.err_share_list, Toast.LENGTH_LONG).show();
+            return;
+        }
 
         try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream()) {
             ShoppingListMarshaller.marshall(outputStream, list);
@@ -209,7 +214,11 @@ public boolean onOptionsItemSelected(MenuItem item) {
                 return true;
             case R.id.action_delete_list:
                 message = getString(R.string.confirm_delete_list, getTitle());
-                ConfirmationDialog.show(this, message, R.id.action_delete_list);
+                if (getBinder().hasList(currentListName)) {
+                    ConfirmationDialog.show(this, message, R.id.action_delete_list);
+                } else {
+                    Toast.makeText(this, R.string.err_cannot_delete_list, Toast.LENGTH_LONG).show();
+                }
                 return true;
             case R.id.action_new_list:
                 NewListDialog.Builder builder = new TextInputDialog.Builder(this, NewListDialog.class);
@@ -243,6 +252,9 @@ public boolean onOptionsItemSelected(MenuItem item) {
 
     private void sort(final boolean ascending) {
         ShoppingList list = getBinder().getList(currentListName);
+        if (list == null) {
+            return;
+        }
         list.sort(new Comparator<ListItem>() {
             @Override
             public int compare(ListItem o1, ListItem o2) {
@@ -254,6 +266,9 @@ public int compare(ListItem o1, ListItem o2) {
 
     private void sortByChecked(final boolean checkedFirst) {
         ShoppingList list = getBinder().getList(currentListName);
+        if (list == null) {
+            return;
+        }
         list.sort(new Comparator<ListItem>() {
             @Override
             public int compare(ListItem o1, ListItem o2) {
@@ -278,9 +293,13 @@ public void onPositiveButtonClicked(int action) {
                 }
                 break;
             case R.id.action_delete_list:
-                getBinder().removeList(getTitle().toString());
-                updateDrawer();
-                selectList(0);
+                boolean success = getBinder().removeList(getTitle().toString());
+                if (!success) {
+                    Toast.makeText(this, R.string.err_cannot_delete_list, Toast.LENGTH_LONG).show();
+                } else {
+                    updateDrawer();
+                    selectList(0);
+                }
                 break;
         }
     }

app/src/main/java/com/woefe/shoppinglist/shoppinglist/ShoppingListMarshaller.java

@@ -19,13 +19,15 @@
 
 package com.woefe.shoppinglist.shoppinglist;
 
+import android.support.annotation.NonNull;
+
 import java.io.BufferedWriter;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
 
 public class ShoppingListMarshaller {
-    public static void marshall(OutputStream stream, ShoppingList list) throws IOException {
+    public static void marshall(@NonNull OutputStream stream, @NonNull ShoppingList list) throws IOException {
 
         try (BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(stream))) {
             writer.write("[ ");

app/src/main/java/com/woefe/shoppinglist/shoppinglist/ShoppingListService.java

@@ -88,10 +88,11 @@ public void addList(String listName) throws ShoppingListException {
             manager.addList(listName);
         }
 
-        public void removeList(String listName) {
-            manager.removeList(listName);
+        public boolean removeList(String listName) {
+            return manager.removeList(listName);
         }
 
+        @Nullable
         public ShoppingList getList(String listName) {
             return manager.getList(listName);
         }
@@ -101,7 +102,7 @@ public boolean hasList(String listName) {
         }
 
         public String[] getListNames() {
-            String[] names = manager.getListNames().toArray(new String[0]);
+            String[] names = manager.getListNames().toArray(new String[manager.size()]);
             Arrays.sort(names, new Comparator<String>() {
                 @Override
                 public int compare(String o1, String o2) {

app/src/main/java/com/woefe/shoppinglist/shoppinglist/ShoppingListsManager.java

@@ -40,7 +40,7 @@
  */
 class ShoppingListsManager {
     private static final String TAG = ShoppingListsManager.class.getSimpleName();
-    public static final String FILE_ENDING = ".lst";
+    private static final String FILE_ENDING = ".lst";
 
     private final Map<String, ShoppingListMetadata> trashcan = new HashMap<>();
     private final MetadataContainer shoppingListsMetadata = new MetadataContainer();
@@ -144,7 +144,7 @@ private void loadFromDirectory(String directory) {
         }
     }
 
-    private void addShoppingList(ShoppingList list, String filename) {
+    private ShoppingListMetadata addShoppingList(ShoppingList list, String filename) {
         final ShoppingListMetadata metadata = new ShoppingListMetadata(list, filename);
         list.addListener(new ShoppingList.ShoppingListListener() {
             @Override
@@ -154,6 +154,7 @@ public void onShoppingListUpdate(ShoppingList list) {
         });
         setupObserver(metadata);
         shoppingListsMetadata.add(metadata);
+        return metadata;
     }
 
     private void setupObserver(final ShoppingListMetadata metadata) {
@@ -203,17 +204,26 @@ void addList(String name) throws ShoppingListException {
         }
 
         String filename = new File(this.directory, name + FILE_ENDING).getPath();
-        addShoppingList(new ShoppingList(name), filename);
-        shoppingListsMetadata.getByName(name).isDirty = true;
+        ShoppingListMetadata metadata = addShoppingList(new ShoppingList(name), filename);
+        metadata.isDirty = true;
     }
 
-    void removeList(String name) {
-        ShoppingListMetadata toRemove = shoppingListsMetadata.removeByName(name);
-        trashcan.put(toRemove.shoppingList.getName(), toRemove);
+    boolean removeList(String name) {
+        if (hasList(name)) {
+            ShoppingListMetadata toRemove = shoppingListsMetadata.removeByName(name);
+            trashcan.put(toRemove.shoppingList.getName(), toRemove);
+            return true;
+        }
+        return false;
     }
 
+    @Nullable
     ShoppingList getList(String name) {
-        return shoppingListsMetadata.getByName(name).shoppingList;
+        ShoppingListMetadata metadata = shoppingListsMetadata.getByName(name);
+        if (metadata != null) {
+            return metadata.shoppingList;
+        }
+        return null;
     }
 
     Set<String> getListNames() {
@@ -279,6 +289,7 @@ private ShoppingListMetadata removeByFile(String filename) {
             return toRemove;
         }
 
+        @Nullable
         private ShoppingListMetadata getByName(String name) {
             return byName.get(name);
         }

app/src/main/res/values/strings.xml

@@ -60,4 +60,6 @@
     <string name="duplicate_warning">\'%s\' is already on the list</string>
     <string name="checked_first">Checked first</string>
     <string name="unchecked_first">Unchecked first</string>
+    <string name="err_cannot_delete_list">Cannot delete list</string>
+    <string name="err_share_list">Cannot share list</string>
 </resources>