cargoship19.java

Thinking in Java第四版 课后习题的源码

// generics/CargoShip19.java
// TIJ4 Chapter Generics, Exercise 19, page 649
// Following the form of Store.java, build a model of a containerized 
// cargo ship.
import java.util.*;
import net.mindview.util.*;

class Item {
	private final int id;
	private String description;
	private String destination;
	private double price;
	public Item(int idNumber, String what, String whereTo, double price) {
		id = idNumber;
		description = what;
		destination = whereTo;
		this.price = price;
		System.out.println(toString());
	} 
	public String toString() {
		return id + ", " + description + ", " + "$" + price + ", to: " +
			destination;
	}
	public void priceChange(double change) {
		price += change;
	}
	public static Generator<Item> generator = 
		new Generator<Item>() {
			private Random rand = new Random();
			public Item next() {
				return new Item(rand.nextInt(1000), 
				"Very nice ... ",  "Destination: ...", 
				Math.round(rand.nextDouble() * 1000.0)); 
			}
		};
}

class Shelf extends ArrayList<Item> {
	public Shelf(int nItems) {
		Generators.fill(this, Item.generator, nItems);
	}
}

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

class Deck extends ArrayList<StorageArea> {
	public Deck(int nStorageAreas, int nShelves, int nItems) {
		for(int i = 0; i < nStorageAreas; i++)
			add(new StorageArea(nShelves, nItems));
	}
}

class Office {}

public class CargoShip19 extends ArrayList<Deck> {
	private Office office;
	public CargoShip19(int nDecks, int nStorageAreas, int nShelves, int nItems) {
		for(int i = 0; i < nDecks; i++)
			add(new Deck(nStorageAreas, nShelves, nItems));
	}	
	public String toString() {
		StringBuilder result = new StringBuilder();
		for(Deck d : this)
			for(StorageArea sa : d)
				for(Shelf s : sa)
					for(Item i : s) {
						result.append(i);
						result.append('\n');
					}
		return result.toString();
	}
	public static void main(String[] args) {
		System.out.println(new CargoShip19(3, 4, 3, 10));
	}
}