尝试完成VendItem＆amp;的方法。 Restock ..我不太明白我是怎么想把参数中给出的项目添加到HashMap中的。有人可以解释一下如何完成这个吗？
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.ArrayList;
import java.util.Scanner;
public class Solution {
/**
* The top portion of this class is the main driver and interface, and
* other classes needed to setup the coding challenge.
*
* Located at the end of this file is the VendingMachineImpl class.
* Please code your solution in the VendingMachineImpl class (stubbed out below).
*/
public static void main(String args[]) throws Exception {
// please do not alter this method.
Collection<VendingMachine.Product> products = null;
Collection<VendingMachine.Coin> coins = null;
String itemName = null;
Collection<VendingMachine.Coin> tender = null;
Solution.VendingMachine.VendResult result = null;
Scanner input = new Scanner(System.in);
String line = input.nextLine();
if (line != null && !"".equals(line.trim())) {
Scanner productLine = new Scanner(line);
products = new ArrayList<VendingMachine.Product>();
while (productLine.hasNext()) {
String name = productLine.next();
Integer price = productLine.nextInt();
products.add(new VendingMachine.Product(name, price));
}
}
line = input.nextLine();
if (line != null && !"".equals(line.trim())) {
Scanner coinLine = new Scanner(line);
coins = new ArrayList<VendingMachine.Coin>();
while (coinLine.hasNext()) {
String coinName = coinLine.next();
VendingMachine.Coin c = VendingMachine.Coin.valueOf(coinName);
if (c != null) {
coins.add(c);
}
}
}
line = input.nextLine();
if (line != null && !"".equals(line.trim())) {
Scanner vendLine = new Scanner(line);
tender = new ArrayList<VendingMachine.Coin>();
if (vendLine.hasNext()) {
itemName = vendLine.next();
while (vendLine.hasNext()) {
VendingMachine.Coin c = VendingMachine.Coin.valueOf(vendLine.next());
if (c != null) {
tender.add(c);
}
}
}
}
VendingMachine vm = new VendingMachineImpl();
vm.restock(products, coins);
if (itemName != null) {
result = vm.vendItem(itemName, tender);
}
System.out.print(getTotalItemCount(vm.getItemCount()));
System.out.print(" ");
System.out.print(getCoinAmount(vm.getCoinCount()));
if (result != null) {
System.out.print(" ");
System.out.print(getCoinAmount(result.getChange()));
}
}
// please do not alter this method.
private static int getTotalItemCount(Map<String, Integer> products) {
int totalCount = 0;
if (products != null) {
for (Integer count : products.values()) {
if (count != null && count.intValue() > 0) {
totalCount += count.intValue();
}
}
}
return totalCount;
}
// please do not alter this method.
private static int getCoinAmount(Collection<Solution.VendingMachine.Coin> coins) {
int totalAmount = 0;
for (Solution.VendingMachine.Coin coin : coins) {
totalAmount += coin.getValue();
}
return totalAmount;
}
// please do not alter this method.
private static int getCoinAmount(Map<Solution.VendingMachine.Coin, Integer> coins) {
int totalAmount = 0;
if (coins != null) {
for (Solution.VendingMachine.Coin coin : coins.keySet()) {
Integer count = coins.get(coin);
if (count != null && count.intValue() > 0) {
totalAmount += (count.intValue() * coin.getValue());
}
}
}
return totalAmount;
}
/**
* The Vending Machine Interface (please do not alter this interface)
* A coin-operated machine to automate the sale and dispensing of items to a customer.
*/
public interface VendingMachine {
/**
* The restock method is intended to be used by the machine owner to
* stock item inventory and/or coin inventory into the vending machine.
* This method may be invoked more than once in the life-cycle of an
* instance.
* @param items - the products to add the product inventory
* @param funds - the coins to add to the coin inventory
*/
public void restock(Collection<Product> items, Collection<Coin> coins);
/**
* The vend method is the principle purchase method. It returns the
* amount of change in cents when able to vend. When unable to vend for
* any reason this method returns the full amount tendered.
* Money tendered less any change becomes funds if and only if able to
* vend.
* This method may be invoked more than once in the life-cycle of an
* instance.
* @param itemName - the name of the product desired to purchase
* @param tender - the coins offered for payment
* @return change (if due) in coins (or an empty collection) when no
* change is due and the full tender amount when unable to vend.
*/
public VendResult vendItem(String itemName, Collection<Coin> tender);
/**
* Inquires for the product inventory
* @return the current state of product inventory or null when no
* products exist.
*/
public Map<String, Integer> getItemCount();
/**
* Inquires for the funds inventory
* @return the current state of the funds inventory or null when no
* funds exist.
*/
public Map<Coin, Integer> getCoinCount();
/**
* Coin Enum - US based currency Each token represents a kind of coin
* and its value, in cents (USD). Note: Penny(1) //$0.01 is
* intentionally not defined
*/
public enum Coin {
DOLLAR(100), // $1.00
QUARTER(25), // $0.25
DIME(10), // $0.10
NICKEL(5); // $0.05
int cents = 0;
Coin(int cents) {
this.cents = cents;
}
public int getValue() {
return cents;
}
};
/**
* The Product Class (please do not alter this class)
* A Product represents an item to vend. Vend items have a name and price.
* Prices for an item are instance controlled by Product name.
* All items with the same name have the same price.
*/
public static final class Product {
private static final Map<String, Integer> priceMap = new HashMap();
private final String itemName;
Product(String itemName, int price) {
this.itemName = String.valueOf(itemName);
priceMap.put(itemName, Integer.valueOf(price));
}
public String getItemName() {
return itemName;
}
public int getPrice() {
return priceMap.get(itemName).intValue();
}
@Override public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((itemName == null) ? 0 : itemName.hashCode());
return result;
}
@Override public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Product other = (Product)obj;
if (itemName == null) {
if (other.itemName != null) {
return false;
}
} else if (!itemName.equals(other.itemName)) {
return false;
}
return true;
}
@Override public String toString() {
return "Product [itemName=" + itemName + ", price=" + getPrice() + "]";
}
}
/**
* VendResult (please do not alter this class)
* Captures the results of a vend attempt.
* @item - the item purchased
* @change - the coins returned
*/
public static final class VendResult {
private final Product item;
private final Collection<Coin> change;
public VendResult(Product product, Collection<Coin> change) {
this.item = product;
this.change = change;
}
public Product getItem() {
return item;
}
public Collection<Coin> getChange() {
return change;
}
}
}
/***********************************************
* VendingMachineImpl. Code your solution here!
***********************************************/
public static class VendingMachineImpl implements VendingMachine {
private static Map<Coin, Integer> Coins = new HashMap();
private static Map<String, Integer> inventory = new HashMap();
// $TODO - replace this line; define any instance variables, e
@Override public void restock(Collection<Product> items, Collection<Coin> coins) {
// $TODO - replace this line; implement restock
}
@Override public VendResult vendItem(String itemName, Collection<Coin> tender) {
// $TODO - replace this line; implement vendItem
}
@Override public Map<String, Integer> getItemCount() {
// $TODO - replace this line; implement getItemCount
if(inventory.isEmpty()){
return null;
}
else{
return inventory;
}
}
@Override public Map<Coin, Integer> getCoinCount() {
// $TODO - replace this line; implement getCoinCount
if(Coins.isEmpty()){
return null;
}
else{
return Coins;
}
}
// $TODO - replace this line; define any helper methods if/as needed.
}
}
答案 0 :(得分：1)
因此，您想要在restock方法中执行的操作（所有其他方法都是模拟的）是将Products添加到广告资源中，以及硬币。那它会是什么样子？
private static Map<Coin, Integer> Coins = new HashMap();
private static Map<String, Integer> inventory = new HashMap()
@Override
public void restock(Collection<Product> items, Collection<Coin> coins) {
for(Product item : items) {
int quantity = inventory.get(item.getItemName());
inventory.put(item.getItemName(), inventory.get(item.getItemName()) + 1);
}
for(Coin coin : coins) {
Coins.put(coin, coin.get(coin) + 1);
}
}
文档不是很好。
/** * The restock method is intended to be used by the machine owner to * stock item inventory and/or coin inventory into the vending machine. * This method may be invoked more than once in the life-cycle of an * instance. * @param items - the products to add the product inventory * @param funds - the coins to add to the coin inventory */
我没有说每次补货时是否要添加多个物品或硬币。您可能想与老师澄清这一点。但我希望你明白这一点。