内部类

package com.tech.Apple;

import com.sun.javaws.Main;

import java.util.ArrayList;

public class Invoice {
    private static class Item{
        String description;
        int quantity;
        double unitPrice;

        public String getDescription() {
            return description;
        }

        public int getQuantity() {
            return quantity;
        }

        public double getUnitPrice() {
            return unitPrice;
        }

        public Item() {
        }

        public Item(String description, int quantity, double unitPrice) {
            this.description = description;
            this.quantity = quantity;
            this.unitPrice = unitPrice;
        }
        double price(){
            return quantity * unitPrice;
        }
    }
    private ArrayList<Item> items = new ArrayList<>();
    public void add(Item item){
        items.add(item);
        System.out.println(item.getDescription() + "	" + item.getQuantity() + "	" + item.getUnitPrice() + "	" + item.price());
    }
    public void addItem(String description, int quantity, double unitPrice){
        Item item = new Item();
        item.description = description;
        item.quantity = quantity;
        item.unitPrice = unitPrice;
        System.out.println(item.getDescription() + "	" + item.getQuantity() + "	" + item.getUnitPrice() + "	" + item.price());
    }


    public static void main(String[] args) {
            Invoice.Item newItem = new Invoice.Item("BlackWell Toaster",2,19.95);
            System.out.println(newItem.getDescription() + "	" + newItem.getQuantity() + "	" + newItem.getUnitPrice() + "	" + newItem.price());
            Invoice iv = new Invoice();
            iv.add(newItem);
            iv.addItem("pen",2,5);

    }

}