ItemRegister class is superclass for IncomeRegister and ExpenseRegister

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

+package no.ntnu.idatt1002.demo.data.Economics;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Register class for storing Item-objects.
+ */
+public abstract class ItemRegister{
+    private final List<Item> items;
+
+    /**
+     * An "empty" class constructor.
+     */
+    public ItemRegister(){
+        this.items = new ArrayList<>();
+    }
+
+    /**
+     * Class constructor.
+     * @param items an ArrayList with Item´s you want to overview.
+     */
+    public ItemRegister(ArrayList<Item> items){
+        this.items = items;
+    }
+
+    /**
+     * Check if the register has Item´s.
+     * @return true or false depending on if items is empty.
+     */
+    public boolean hasItems(){
+        return items.isEmpty();
+    }
+
+    /**
+     * Get the sum of all Item´s in items
+     * @return sum of all Item´s
+     */
+    public double getTotalSum(){
+        return items.stream().map(Item::getAmount).mapToDouble(Double::doubleValue).sum();
+    }
+}