泛型实现多维数组

这个是《Thinking In Java》里头的代码

import util.Generator;

import java.util.ArrayList;
import java.util.Random;

/**
 * Created with IntelliJ IDEA.
 * User: 贺志军
 * Date: 2014/6/19
 * Time: 16:26
 * To change this template use File | Settings | File Templates.
 */
class Product {
    private final int id;
    private String description;
    private double price;

    public Product(int IDnumber, String descr, double price) {
        id = IDnumber;
        description = descr;
        this.price = price;
        System.out.println(toString());
    }

    public String toString() {
        return id + ": " + description + ", price: $" + price;
    }

    public void priceChange(double change) {
        price += change;
    }

    public static Generator generator = new Generator() {
        private Random rand = new Random(47);
        @Override
        public Product next() {
            return new Product(rand.nextInt(1000), "Test", Math.round(rand.nextDouble() * 1000.0) + 0.99);
        }
    };
}

class Shelf extends ArrayList {
    public Shelf(int nProducts) {
        Generators.fill(this, Product.generator, nProducts);
    }
}

class Aisle extends ArrayList {
    public Aisle(int nShelves, int nProducts) {
        for (int i = 0; i < nShelves; i++)
            add(new Shelf(nProducts));
    }
}

class CheckoutStand {}
class Office {}
public class Store extends ArrayList {
    private ArrayList checkouts = new ArrayList();
    private Office office = new Office();

    public Store(int nAisles, int nShelves, int nProducts) {
        for (int i = 0; i < nAisles; i++)
            add(new Aisle(nShelves, nProducts));
    }

    public String toString() {
        StringBuilder result = new StringBuilder();
        for (Aisle a : this)
            for (Shelf s : a)
                for (Product p : s) {
                    result.append(p);
                    result.append("\n");
                }
        return result.toString();
    }

    public static void main(String[] args) {
        System.out.println(new Store(14, 5, 10));
    }
}

代码并不完整，还依赖了其他的package里头的，但是足以说明问题。

class Shelf extends ArrayList

表明Shelf的对象就是一维List

class Aisle extends ArrayList

表明Aisle的对象就是二维List

同理

public class Store extends ArrayList

则每个Store对象都是三维的List

不需要考智力的写法。