diff --git a/app/src/main/java/org/cutem/cutecalendar/presenter/PaintCalendarStrategy.java b/app/src/main/java/org/cutem/cutecalendar/presenter/PaintCalendarStrategy.java
index 93eb3c3..95551c4 100644
--- a/app/src/main/java/org/cutem/cutecalendar/presenter/PaintCalendarStrategy.java
+++ b/app/src/main/java/org/cutem/cutecalendar/presenter/PaintCalendarStrategy.java
@@ -59,6 +59,7 @@ public class PaintCalendarStrategy {
     private void emptyButton(Button btn) {
         if (btn != null) {
             btn.setOnAction(e -> {
+                // empty
             });
 
             btn.setText("");
diff --git a/app/src/main/java/org/cutem/cutecalendar/presenter/Presenter.java b/app/src/main/java/org/cutem/cutecalendar/presenter/Presenter.java
index 4477213..429e419 100644
--- a/app/src/main/java/org/cutem/cutecalendar/presenter/Presenter.java
+++ b/app/src/main/java/org/cutem/cutecalendar/presenter/Presenter.java
@@ -217,8 +217,8 @@ public abstract class Presenter {
     }
 
     protected final void finishTodoItem(@NotNull TodoItem item) {
-        item = TodoItemUtil.finishSingleTodoItem(item);
-        addTodoItem(item);
+        TodoItem newItem = TodoItemUtil.finishSingleTodoItem(item);
+        addTodoItem(newItem);
     }
 
 
diff --git a/app/src/main/java/org/cutem/cutecalendar/presenter/ShowTodoItemDetailStrategy.java b/app/src/main/java/org/cutem/cutecalendar/presenter/ShowTodoItemDetailStrategy.java
index 1550b02..ebf0e6e 100644
--- a/app/src/main/java/org/cutem/cutecalendar/presenter/ShowTodoItemDetailStrategy.java
+++ b/app/src/main/java/org/cutem/cutecalendar/presenter/ShowTodoItemDetailStrategy.java
@@ -77,7 +77,7 @@ public class ShowTodoItemDetailStrategy {
 
         // personnel
         List<String> ps = item.getPersonnel();
-        if (ps.size() > 0) {
+        if (!ps.isEmpty()) {
             builder.append("\npeople:");
             for (String p : ps) {
                 builder.append("\n\t").append(p);