ItemOverview.java

package no.ntnu.idatt1002.demo.data;

import java.util.ArrayList;

/**
 * ItemOverview is a class for storing and getting
 * information on items. It is meant for storing EITHER
 * Income or Expense
 */
public abstract class ItemOverview {
    ArrayList<Item> items;

    /**
     * An "empty" class constructor.
     */
    public ItemOverview(){
        this.items = new ArrayList<>();   //ArrayList for storing item´s
    }

    /**
     * Class constructor that takes in an ArrayList of Item´s as argument
     * @param items   An ArrayList of the Item´s you want to overview
     */
    public ItemOverview(ArrayList<Item> items){
        this.items = items;
    }

    /**
     * Get an ArrayList of every item.
     * @return   item ArrayList.
     */
    public ArrayList<Item> getItems() {
        return items;
    }

    /**
     * Add an Item object to items.
     * @param newItem   The Item you want to add.
     */
    public void addItem(Item newItem){
        if(items.contains(newItem)){
            throw new IllegalArgumentException("This item is already registered");
        }
        items.add(newItem);
    }

    /**
     * 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();
    }
}