作为学习过程的一部分，我正在用Java创建一个小程序，该程序将帮助虚构的公司销售汉堡。
在下面的代码中，我为一个汉堡包创建了一个类，并添加了一些选项以向汉堡包添加其他食物（如生菜，胡萝卜等）。
我面临的问题是如何在不过多使用if-else的情况下检查基本汉堡包（基本汉堡包仅指面包和肉类）中的每一个额外添加物。我尝试的一种方法（您也可以在代码中看到）是为每个添加项分配一个数字，例如，生菜1，胡萝卜2等。将1和2相加得到3；我们可以寻找3来查找是否添加了生菜和胡萝卜，以便我们可以计算价格。我也用其他选择做到了这一点。
但是出现了一些问题：
在某些情况下，通过加法生成的数字是由不同的加法创建的两次，这可以通过将数字乘以某个数字或在我创建更多边沿案例时加1来解决。
< / li>通过创建此类案例，我的主要问题是，它将需要大量if-else语句，为了有效地编写所需代码，我试图避免这些语句。
请建议是否还有其他方法。请注意，代码尚未完成，因为我不想创建更多的if-else语句（在汉堡包类；方法cal_price中）来检查添加内容，但足以完全理解代码的性质。代码如下：
public class Main {
public static void main(String[] args) {
Breadroll breadroll_type = new Breadroll("Sesame Seed Bun");
meat meat_type = new meat("Beef");
Hamburger my_burger = new Hamburger("Hamburger",breadroll_type,meat_type);
my_burger.select_items(1,2,3,4);
my_burger.cal_price();
my_burger.getBreadroll_type();
my_burger.getMeat_type();
}
}
public class Breadroll {
private String breadroll_type;
public Breadroll(String breadroll_type) {
this.breadroll_type = breadroll_type;
}
public String getBreadroll_type() {
return breadroll_type;
}
}
public class meat {
private String meat_type;
public meat(String meat_type) {
this.meat_type = meat_type;
}
public String getMeat_type() {
return meat_type;
}
}
public class Hamburger {
private String name;
Breadroll breadroll_type;
meat meat_type;
private double base_price; //Price without addons
private int lettuce;
private int carrot;
private int tomato;
private int cheese;
private int hot_sauce;
private int mustard;
private int total_select;
public Hamburger(String name, Breadroll breadroll_type, meat meat_type) {
this.name = name;
this.breadroll_type = breadroll_type;
this.meat_type = meat_type;
this.base_price = 2.75;
}
public void select_items(int lettuce, int carrot, int tomato, int cheese) {
this.lettuce = lettuce;
this.carrot = carrot;
this.tomato = tomato;
this.cheese = cheese;
this.total_select = lettuce + carrot + tomato + cheese;
}
public void cal_price()
{
double final_price;
double lettuce_price = 0.50;
double carrots_price = 0.60;
double tomatos_price = 0.70;
double cheese_price = 0.85;
if(total_select == 0) {
System.out.println("Order Placed : Hamburger with no additions " + getBase_price() + "$");
}
else if (total_select == 1) {
final_price = getBase_price() + lettuce_price;
System.out.println("Order Placed : Hamburger with all lettuce " + (float) final_price + "$");
}
else if (total_select == 2) {
final_price = getBase_price() + carrots_price;
System.out.println("Order Placed : Hamburger with all carrot " + (float) final_price + "$");
}
else if (total_select == 3) {
final_price = getBase_price() + tomatos_price;
System.out.println("Order Placed : Hamburger with all tomato " + (float) final_price + "$");
}
else if (total_select == 4) {
final_price = getBase_price() +cheese_price;
System.out.println("Order Placed : Hamburger with all cheese " + (float) final_price + "$");
}
else if (total_select*100 == 1000) {
final_price = getBase_price() + lettuce_price + carrots_price + tomatos_price + cheese_price;
System.out.println("Order Placed : Hamburger with all additions " + (float) final_price + "$");
}
}
public String getName() {
return name;
}
public void getBreadroll_type() {
System.out.println(breadroll_type.getBreadroll_type());
}
public void getMeat_type() {
System.out.println(meat_type.getMeat_type());
}
public double getBase_price() {
return base_price;
}
public int getLettuce() {
return lettuce;
}
public int getCarrot() {
return carrot;
}
public int getTomato() {
return tomato;
}
public int getCheese() {
return cheese;
}
}
答案 0 :(得分：0)
您对“汉堡包”对象的实现似乎有些复杂。通常，面向对象的程序设计代表实际的物理对象，应选择最简单，最原子的属性，以避免出现此类情况。一个汉堡包有或没有生菜。它有或没有番茄。我的建议是为每个浇头使用单独的布尔变量，或者根据需要使用布尔数组表示浇头。然后，将get_price（）方法添加到您的Hamburger中，该方法只有一个if语句块用于计算价格。如果您真的想加入OOP，则每个浇头都可以是一个带有价格的对象，您可以将该价格附加到汉堡包的Toppings ArrayList上。然后，您的get_price（）方法将使用for-each来总计Topping对象的所有价格以及汉堡包的price属性。如果您想要多个相同的浇头，则此方法可能更好。这是编程中最有趣的部分-您可以选择最适合自己的实现，然后尝试一下！
答案 1 :(得分：0)
制作一个具有名称，面包类型，肉类类型的汉堡包，并在以后添加额外的汉堡包，您也可以对面包类和肉类进行单独的选择。在extra方法中，我们预先计算了多余的价格，因此调用getPrice（）可以将所选的面包/肉类类型的所有多余的东西相加。还有其他方法可以执行此操作，但是通过这种方法，您还将获得合同和转换语句的示例。删除了一些成分，但您明白了。
还要看看命名约定与您的命名约定有何不同。
class HamburgerContract {
// Specify your constants in this class so all classes are able to communicate with the same values
// Change the name to something shorter like HBC for easier reference, ie HBC.BR_TYPE_SESAM
public static final int BR_TYPE_SESAM = 1;
public static final int BR_TYPE_HONEY = 2;
public static final int MEAT_TYPE_COW = 1;
public static final int MEAT_TYPE_CHICKEN = 2;
}
public class Hamburger {
public static void main(String[] args) {
// Made a hamburger with name, breadtype, meattype and added the extra's later on
// You can make seperate methods for the breadtype and meat as well
// In the extra methods we calculate the extra price beforehand
// So calling getPrice() sums up all the extras with chosen bread/meat type
// There are other ways to do this but this way you'll also have an example of a contract and switch statement
// Removed a few ingredients but you get the point
Hamburger myHamburger = new Hamburger("Varadero Burger", HamburgerContract.BR_TYPE_SESAM, HamburgerContract.MEAT_TYPE_CHICKEN, 2.50);
myHamburger.addCarrot();
myHamburger.addLettuce();
myHamburger.removeCarrot();
System.out.print("The price of your " + myHamburger.getName() + "is $ " + myHamburger.getPrice());
}
private String burgerName;
private int breadrollType;
private int meatType;
private boolean lettuce;
private boolean carrot;
private double basePrice;
private double extraPrice;
public Hamburger(String burgerName, int breadrollType, int meatType, double basePrice) {
this.burgerName = burgerName;
this.breadrollType = breadrollType;
this.meatType = meatType;
this.basePrice = basePrice;
this.extraPrice = 0;
this.lettuce = false;
this.carrot = false;
}
public void addLettuce() {
// extra check if lettuce is not already added, so you wont add to the price twice
// same goes for removing the lettuce or the carrot methods
if (!lettuce) {
letuce = true;
extraPrice += 0.25;
}
}
public removeLettuce() {
if (lettuce) {
letuce = false;
extraPrice -= 0.25;
}
}
public void addCarrot() {
if (!carrot) {
carrot = true;
extraPrice += 0.20;
}
}
public void removeCarrot() {
if (carrot) {
carrot = false;
extraPrice -= 0.20;
}
}
public String getName() {
return burgerName;
}
public double getPrice() {
switch (breadrollType) {
case HamburgerContract.BR_TYPE_HONEY: extraPrice += 0.25; break;
case HamburgerContract.BR_TYPE_SESAM: extraPrice += 0.50; break;
}
switch (meatType) {
case HamburgerContract.MEAT_TYPE_COW: extraPrice += 0; break;
case HamburgerContract.MEAT_TYPE_CHICKEN: extraPrice += 0.50; break;
}
return basePrice + extraPrice;
}
}
答案 2 :(得分：-1)
您根本不需要使用条件语句，只需将每个商品的价格乘以其价格即可：
final_price = getBase_price()
+ lettuce_num * lettuce_price
+ carrots_num * carrots_price
+ tomatos_num * tomatos_price
+ cheese_num * cheese_price;
然后在您的设置方法中，您应该设置项目的数量/数量（例如生菜），而不是1 ==生菜和2 == xxx：
my_burger.select_items(5,0,0,0); // 5 lettuce, 0 all other
my_burger.select_items(1,0,0,90); // 1 lettuce, 90 cheese, 0 all other
将它们放在一起（最小）：
public class Main {
public static void main(String[] args) {
Hamburger my_burger = new Hamburger("Hamburger");
my_burger.select_items(
100, // 100 lettuce
0, // 0 carrot
2, // 2 tomato
1); // 1 cheese
my_burger.cal_price();
}
}
public class Hamburger {
private String name;
private double base_price = 2.75;
private int lettuce;
private double lettuce_price = 0.50;
private int carrot;
private double carrots_price = 0.60;
private int tomato;
private double tomatos_price = 0.70;
private int cheese;
private double cheese_price = 0.85;
public Hamburger(String name) {
this.name = name;
}
public void select_items(int lettuce, int carrot, int tomato, int cheese) {
this.lettuce = lettuce;
this.carrot = carrot;
this.tomato = tomato;
this.cheese = cheese;
}
public void cal_price()
{
double final_price = getBase_price()
+ lettuce * lettuce_price
+ carrots * carrots_price
+ tomato * tomatos_price
+ cheese * cheese_price;
// TODO print price
}
}