- 材料はIS-Aサンドイッチではありません。
- 柔軟な変更を可能にするために、原材料の価格を外部化することをお勧めします。
- クラスレベルでハードコーディングするのではなく、その成分に基づいて実行時にサンドイッチの説明を生成することをお勧めします。
- 材料はサンドイッチについて何も知らないはずです。
だから、私は次の解決策を提供します：
package com;
public enum Ingredient {
CHEESE, TOMATO, LETTUCE, BACON, BREAD, MEATBALL, ITALIAN_SAUCE;
private final String description;
Ingredient() {
description = toString().toLowerCase();
}
Ingredient(String description) {
this.description = description;
}
public String getDescription() {
return description;
}
}
package com;
import static com.Ingredient.*;
import java.util.*;
import static java.util.Arrays.asList;
public enum SandwitchType {
BLT(
asList(TOMATO, LETTUCE, BACON, BREAD),
1 , 1, 1 , 1
),
SUB(
asList(MEATBALL, CHEESE, ITALIAN_SAUCE, BREAD),
1 , 1 , 1 , 1
);
private final Map<Ingredient, Integer> ingredients = new EnumMap<Ingredient, Integer>(Ingredient.class);
private final Map<Ingredient, Integer> ingredientsView = Collections.unmodifiableMap(ingredients);
SandwitchType(Collection<Ingredient> ingredients, int ... unitsNumber) {
int i = -1;
for (Ingredient ingredient : ingredients) {
if (++i >= unitsNumber.length) {
throw new IllegalArgumentException(String.format("Can't create sandwitch %s. Reason: given ingedients "
+ "and their units number are inconsistent (%d ingredients, %d units number)",
this, ingredients.size(), unitsNumber.length));
}
this.ingredients.put(ingredient, unitsNumber[i]);
}
}
public Map<Ingredient, Integer> getIngredients() {
return ingredientsView;
}
public String getDescription() {
StringBuilder result = new StringBuilder();
for (Ingredient ingredient : ingredients.keySet()) {
result.append(ingredient.getDescription()).append(", ");
}
if (result.length() > 1) {
result.setLength(result.length() - 2);
}
return result.toString();
}
}
package com;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
public class PriceList {
private static final int PRECISION = 2;
private final ConcurrentMap<Ingredient, Double> prices = new ConcurrentHashMap<Ingredient, Double>();
public double getPrice(SandwitchType sandwitchType) {
double result = 0;
for (Map.Entry<Ingredient, Integer> entry : sandwitchType.getIngredients().entrySet()) {
Double price = prices.get(entry.getKey());
if (price == null) {
throw new IllegalStateException(String.format("Can't calculate price for sandwitch type %s. Reason: "
+ "no price is defined for ingredient %s. Registered ingredient prices: %s",
sandwitchType, entry.getKey(), prices));
}
result += price * entry.getValue();
}
return round(result);
}
public void setIngredientPrice(Ingredient ingredient, double price) {
prices.put(ingredient, round(price));
}
private static double round(double d) {
double multiplier = Math.pow(10, PRECISION);
return Math.floor(d * multiplier + 0.5) / multiplier;
}
}
package com;
import java.util.Map;
import java.util.EnumMap;
public class Dispenser {
private final Map<Ingredient, Integer> availableIngredients = new EnumMap<Ingredient, Integer>(Ingredient.class);
public String buySandwitch(SandwitchType sandwitchType) {
StringBuilder result = new StringBuilder();
synchronized (availableIngredients) {
Map<Ingredient, Integer> buffer = new EnumMap<Ingredient, Integer>(availableIngredients);
for (Map.Entry<Ingredient, Integer> entry : sandwitchType.getIngredients().entrySet()) {
Integer currentNumber = buffer.get(entry.getKey());
if (currentNumber == null || currentNumber < entry.getValue()) {
result.append(String.format("not enough %s (required %d, available %d), ",
entry.getKey().getDescription(), entry.getValue(), currentNumber == null ? 0 : currentNumber));
continue;
}
buffer.put(entry.getKey(), currentNumber - entry.getValue());
}
if (result.length() <= 0) {
availableIngredients.clear();
availableIngredients.putAll(buffer);
return "";
}
}
if (result.length() > 1) {
result.setLength(result.length() - 2);
}
return result.toString();
}
public void load(Ingredient ingredient, int unitsNumber) {
synchronized (availableIngredients) {
Integer currentNumber = availableIngredients.get(ingredient);
if (currentNumber == null) {
availableIngredients.put(ingredient, unitsNumber);
return;
}
availableIngredients.put(ingredient, currentNumber + unitsNumber);
}
}
}
package com;
public class StartClass {
public static void main(String[] args) {
Dispenser dispenser = new Dispenser();
for (Ingredient ingredient : Ingredient.values()) {
dispenser.load(ingredient, 10);
}
PriceList priceList = loadPrices();
while (true) {
for (SandwitchType sandwitchType : SandwitchType.values()) {
System.out.printf("About to buy %s sandwitch. Price is %f...",
sandwitchType, priceList.getPrice(sandwitchType));
String rejectReason = dispenser.buySandwitch(sandwitchType);
if (!rejectReason.isEmpty()) {
System.out.println(" Failed: " + rejectReason);
return;
}
System.out.println(" Done");
}
}
}
private static PriceList loadPrices() {
PriceList priceList = new PriceList();
double i = 0.1;
for (Ingredient ingredient : Ingredient.values()) {
priceList.setIngredientPrice(ingredient, i);
i *= 2;
}
return priceList;
}
}