Made variables final

src/main/java/no/ntnu/idatt1002/demo/data/Economics/Income.java

@@ -13,7 +13,7 @@ import javafx.beans.property.SimpleObjectProperty;
  */
 public class Income extends Item {
 
-  private ObjectProperty<IncomeCategory> category;
+  private final ObjectProperty<IncomeCategory> category;
 
   /**
    * This constructor uses the super constructor to set the fields for 'amount' and 'recurring' and

src/main/java/no/ntnu/idatt1002/demo/data/Economics/Item.java

@@ -213,7 +213,7 @@ public abstract class Item {
    */
   @Override
   public String toString() {
-    String isRecurring = "";
+    String isRecurring;
     if (recurring.get()) {
       isRecurring = "Recurring";
     } else {