如何将 2 个方法循环在一起？
How can I loop 2 methods together?
Question
我是 Java 的新手，我正在努力学习 can.The 我要解决的实际问题在上图中。如果我对问题的描述不够详细，请务必参考图片。我目前正在编写一个与买咖啡有关的 java 程序。我有一种方法可以计算购买咖啡的成本 (BuyCoffee) 和使用的资源量。也有不同类型的咖啡，每种咖啡使用不同数量的资源。我还有另一种方法可以计算咖啡售出后剩余的资源**(getRemainingResources)**。我在循环 getRemainingResources 方法时遇到问题。因此，当我购买一次咖啡时，我拥有的资源量就会减少。我有一种方法来填充这些资源。但每次我尝试再次购买相同的咖啡时，我所剩的资源量并没有减少。我的代码如下
import java.util.Scanner;
public class MethodsTest {
//global variable--starting quantity of resources in machine
static final int water = 400;
static final int milk = 540;
static final int coffeeBean = 120; // in g
static int disposableCups = 9;
static final int cost = 550; //in $
//global variable --refill quantity of resources in machine
static int fillWater, fillMilk, fillCoffeeBeans, fillDisposableCups;
//global variable -- remaining quantity of resources in machine
static int newRemCost, remCost, remWater, remMilk, remCoffeeBean, remDisposableCups;
static int espressoWater, espressoMilk, espressoCoffeeBeans, espressoCost; // Resources for espresso
static int latteWater, latteMilk, latteCoffeeBeans, latteCost;
static int cappuccinoWater, cappuccinoMilk, cappuccinoCoffeeBeans, cappuccinoCost;
static int regWater, regMilk, regCoffeeBeans, regCost; //Resources for regular coffees
static void FillCoffeeMachine() {
Scanner input = new Scanner(System.in);
System.out.println("Write how many ml of water you want to add: ");
fillWater = input.nextInt();
System.out.println("Write how many ml of milk you want to add: ");
fillMilk = input.nextInt();
System.out.println("Write how many grams of coffee beans you want to add: ");
fillCoffeeBeans = input.nextInt();
System.out.println("Write how many disposable cups of coffee you want to add: ");
fillDisposableCups = input.nextInt();
MainMenu();
}
static void BuyCoffee() { //method for buying coffee
disposableCups--;// always decreasing when coffee is sold
class TypesOfCoffee {
void Espresso() { //nested class, since there are different kind of coffee
espressoWater = 250;
espressoMilk = 0;
espressoCoffeeBeans = 16;
espressoCost = 4;
if (remWater > espressoWater && remMilk > espressoMilk && remCoffeeBean > espressoCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < espressoWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remCoffeeBean < espressoCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
void Latte() {
latteWater = 350;
latteMilk = 75;
latteCoffeeBeans = 20;
latteCost = 7;
if (remWater > latteWater && remMilk > latteMilk && remCoffeeBean > latteCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < latteWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remMilk < latteMilk) {
System.out.println("Sorry, not enough milk!");
disposableCups++;
} else if (remCoffeeBean < latteCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
void Cappuccino() {
cappuccinoWater = 200;
cappuccinoMilk = 100;
cappuccinoCoffeeBeans = 12;
cappuccinoCost = 6;
if (remWater > cappuccinoWater && remMilk > cappuccinoMilk && remCoffeeBean > cappuccinoCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < cappuccinoWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remMilk < cappuccinoMilk) {
System.out.println("Sorry, not enough milk!");
disposableCups++;
} else if (remCoffeeBean < cappuccinoCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
void regularCoffee() {
regWater = 200;
regMilk = 50;
regCoffeeBeans = 15;
regCost = 0;
if (remWater > regWater && remMilk > regMilk && remCoffeeBean > regCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < regWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remMilk < regMilk) {
System.out.println("Sorry, not enough milk!");
disposableCups++;
} else if (remCoffeeBean < regCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
}
Scanner input = new Scanner(System.in);
System.out.println("What kind of coffee would you like to buy today?");
System.out.println("""
Please enter:
1 for espresso
2 for latte
3 for cappuccino
4 for a regular coffee
back - to go back to main menu""");
String choice = input.next();
switch (choice) { //lets user choose what type of coffee to buy
case "1":
new TypesOfCoffee().Espresso();
break;
case "2":
new TypesOfCoffee().Latte();
break;
case "3":
new TypesOfCoffee().Cappuccino();
break;
case "4":
new TypesOfCoffee().regularCoffee();
break;
case "back":
MainMenu();
break;
default:
System.out.println("Please enter an option from the above");
}
MainMenu();
}
static void takeMoney() { //method to take the money
System.out.println("I gave you" + " " + "$" + remCost);
newRemCost = remCost;
MainMenu();
}
static void getRemainingResources() {
//TODO --has to loop..but it works only once
remDisposableCups = fillDisposableCups + disposableCups;
boolean found = remDisposableCups > 0; // true for coffee to be sold
while (found) {
remWater = water + fillWater - espressoWater - cappuccinoWater - latteWater;//
remMilk = milk + fillMilk - espressoMilk - cappuccinoMilk - latteMilk;
remCoffeeBean = coffeeBean + fillCoffeeBeans - espressoCoffeeBeans - cappuccinoCoffeeBeans - latteCoffeeBeans;
remCost = cost + espressoCost + cappuccinoCost + latteCost - newRemCost;
//found = remDisposableCups > 0 && remWater>=water && remMilk>=milk&&remCoffeeBean>=coffeeBean;
System.out.println("The coffee machine has: ");
System.out.println(remWater + " " + "ml of water");
System.out.println(remMilk + " " + "ml of milk ");
System.out.println(remCoffeeBean + " " + "g of coffee beans ");
System.out.println(remDisposableCups + " " + "disposable cups ");
System.out.println("$" + remCost + " " + "of money");
found = remDisposableCups < 0;
}
MainMenu();
}
static void MainMenu() { // Gives user option to decide what they want to do
Scanner input = new Scanner(System.in);
System.out.println("Main Menu: " + "\n");
System.out.println("Please choose from the following options below");
System.out.println("""
To buy coffee - Enter buy
To fill the machine - Enter fill
To get cash from machine - Enter take
To see remaining resources - Enter remaining
To exit program - Enter exit""");
String choice = input.next();
switch (choice) {
case "buy":
BuyCoffee();
break;
case "fill":
FillCoffeeMachine();
break;
case "take":
takeMoney();
break;
case "remaining":
getRemainingResources();
break;
case "exit":
System.exit(0);
break;
default:
MainMenu();//goes back to main menu if user types in an unknown value
}
}
public static void main(String[] args) {
MainMenu();
}
}
现在应该走了
但是还有其他错误（除了扫描仪，他们已经告诉过你了）
例如，如果不先“剩余”，你就不能买咖啡（还有：静态变量太多，没有使用 OO ...）。这只是一个例子。
我更正了您要求的错误的代码，但还有很多地方需要更改。
import java.util.Scanner;
public class MethodsTest {
//global variable--starting quantity of resources in machine
static final int water = 40000;
static final int milk = 54000;
static final int coffeeBean = 12000; // in g
static int disposableCups = 900;
static final int cost = 550; //in $
static int remCost = 550; //in $
//global variable --refill quantity of resources in machine
static int fillWater, fillMilk, fillCoffeeBeans, fillDisposableCups;
//global variable -- remaining quantity of resources in machine
static int newRemCost, remWater, remMilk, remCoffeeBean, remDisposableCups;
static int espressoWater, espressoMilk, espressoCoffeeBeans, espressoCost; // Resources for espresso
static int latteWater, latteMilk, latteCoffeeBeans, latteCost;
static int cappuccinoWater, cappuccinoMilk, cappuccinoCoffeeBeans, cappuccinoCost;
static int regWater, regMilk, regCoffeeBeans, regCost; //Resources for regular coffees
static void FillCoffeeMachine() {
Scanner input = new Scanner(System.in);
System.out.println("Write how many ml of water you want to add: ");
fillWater = input.nextInt();
System.out.println("Write how many ml of milk you want to add: ");
fillMilk = input.nextInt();
System.out.println("Write how many grams of coffee beans you want to add: ");
fillCoffeeBeans = input.nextInt();
System.out.println("Write how many disposable cups of coffee you want to add: ");
fillDisposableCups = input.nextInt();
MainMenu();
}
static void BuyCoffee() { //method for buying coffee
disposableCups--;// always decreasing when coffee is sold
class TypesOfCoffee {
void Espresso() { //nested class, since there are different kind of coffee
espressoWater = 250;
espressoMilk = 0;
espressoCoffeeBeans = 16;
espressoCost = 4;
if (remWater > espressoWater && remMilk > espressoMilk && remCoffeeBean > espressoCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < espressoWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remCoffeeBean < espressoCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
void Latte() {
latteWater = 350;
latteMilk = 75;
latteCoffeeBeans = 20;
latteCost = 7;
if (remWater > latteWater && remMilk > latteMilk && remCoffeeBean > latteCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < latteWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remMilk < latteMilk) {
System.out.println("Sorry, not enough milk!");
disposableCups++;
} else if (remCoffeeBean < latteCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
void Cappuccino() {
cappuccinoWater = 200;
cappuccinoMilk = 100;
cappuccinoCoffeeBeans = 12;
cappuccinoCost = 6;
if (remWater > cappuccinoWater && remMilk > cappuccinoMilk && remCoffeeBean > cappuccinoCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < cappuccinoWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remMilk < cappuccinoMilk) {
System.out.println("Sorry, not enough milk!");
disposableCups++;
} else if (remCoffeeBean < cappuccinoCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
void regularCoffee() {
regWater = 200;
regMilk = 50;
regCoffeeBeans = 15;
regCost = 0;
if (remWater > regWater && remMilk > regMilk && remCoffeeBean > regCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < regWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remMilk < regMilk) {
System.out.println("Sorry, not enough milk!");
disposableCups++;
} else if (remCoffeeBean < regCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
}
Scanner input = new Scanner(System.in);
System.out.println("What kind of coffee would you like to buy today?");
System.out.println("""
Please enter:
1 for espresso
2 for latte
3 for cappuccino
4 for a regular coffee
back - to go back to main menu""");
String choice = input.next();
switch (choice) { //lets user choose what type of coffee to buy
case "1":
new TypesOfCoffee().Espresso();
break;
case "2":
new TypesOfCoffee().Latte();
break;
case "3":
new TypesOfCoffee().Cappuccino();
break;
case "4":
new TypesOfCoffee().regularCoffee();
break;
case "back":
MainMenu();
break;
default:
System.out.println("Please enter an option from the above");
}
MainMenu();
}
static void takeMoney() { //method to take the money
System.out.println("I gave you" + " " + "$" + remCost);
newRemCost = remCost;
MainMenu();
}
static void getRemainingResources() {
//TODO --has to loop..but it works only once
remDisposableCups = fillDisposableCups + disposableCups;
boolean found = remDisposableCups > 0; // true for coffee to be sold
while (found) {
remWater = water + fillWater - espressoWater - cappuccinoWater - latteWater;//
remMilk = milk + fillMilk - espressoMilk - cappuccinoMilk - latteMilk;
remCoffeeBean = coffeeBean + fillCoffeeBeans - espressoCoffeeBeans - cappuccinoCoffeeBeans - latteCoffeeBeans;
remCost = remCost + espressoCost + cappuccinoCost + latteCost - newRemCost;
espressoCost = 0;
cappuccinoCost = 0;
latteCost = 0;
//found = remDisposableCups > 0 && remWater>=water && remMilk>=milk&&remCoffeeBean>=coffeeBean;
System.out.println("The coffee machine has: ");
System.out.println(remWater + " " + "ml of water");
System.out.println(remMilk + " " + "ml of milk ");
System.out.println(remCoffeeBean + " " + "g of coffee beans ");
System.out.println(remDisposableCups + " " + "disposable cups ");
System.out.println("$" + remCost + " " + "of money");
found = remDisposableCups < 0;
}
MainMenu();
}
static void MainMenu() { // Gives user option to decide what they want to do
Scanner input = new Scanner(System.in);
System.out.println("Main Menu: " + "\n");
System.out.println("Please choose from the following options below");
System.out.println("""
To buy coffee - Enter buy
To fill the machine - Enter fill
To get cash from machine - Enter take
To see remaining resources - Enter remaining
To exit program - Enter exit""");
String choice = input.next();
switch (choice) {
case "buy":
BuyCoffee();
break;
case "fill":
FillCoffeeMachine();
break;
case "take":
takeMoney();
break;
case "remaining":
getRemainingResources();
break;
case "exit":
System.exit(0);
break;
default:
MainMenu();//goes back to main menu if user types in an unknown value
}
}
public static void main(String[] args) {
MainMenu();
}
}
你写的代码非常复杂，所以你看不出错误在哪里。一些评论：
- Java 是一种面向对象 (OO) 的语言。 OO 范式围绕创建 classes 及其对象、继承和多态性（从父 classes 继承行为，但在每个子 class 中表现不同）。
- 您的代码看起来像是在尝试像旧版本的 Basic 或 Macro Assembler 一样重新创建结构化编程，只是遵守 Java 的语法。您需要真正了解 OO 编程的工作原理，因此首先尝试查找一些相关教程。
- 不要把所有的东西都放在一起class。尝试识别您的应用程序中的不同实体。例如：CoffeMachine、Coffee、Espresso、Latte、RegularCoffee，...为每个已识别的实体创建一个 class。彼此相似的 classes 可能应该是继承的一部分，例如 Espresso、Lattte 等应该继承更通用的 class Coffee（A 继承 B，当你可以说“A is a有点 B").
- 不要使用静态变量（除非有很好的理由，但这种情况很少见）。当您创建它们的对象时，让每个 class 都有自己的实例属性：remainingWater、remainingMilk 等是对象 CoffeeMachine 的属性。它们不是全球性的东西。
- 不要使用 C 或 Basic 中的子例程等静态方法。相反，创建 classes 的对象并调用它们的实例方法。
- 不要像在 Basic 或 Assembler 中那样使用跳转和标签。相反，在循环中调用对象的方法并在必要时中断循环。
- 如果您在应用程序中检测到错误，请使用 Java 的异常机制 - 抛出异常并让调用者处理错误。
- 方法名以Java中的小写字母开头（这是公认的约定，不是句法规则）。
我根据上述原则为您的应用程序创建了不同的设计，因此请先从教程中学习面向对象编程的基础知识，然后将以下代码与您的代码进行比较，看看有什么不同。
Main class（主菜单循环的入口点）：
public class Main
{
public static void main(String[] args)
{
new Main().run();
}
void run()
{
CoffeeMachine coffeeMachine = new CoffeeMachine(400, 540, 120, 9, 550);
while (coffeeMachine.mainMenu()); // loops until mainMenu returns false
}
}
咖啡机：
import java.util.Scanner;
public class CoffeeMachine
{
private Scanner input = new Scanner(System.in);
private int water;
private int milk;
private int coffeeBeans;
private int disposableCups;
private int money;
public CoffeeMachine(int water, int milk, int coffeeBeans, int disposableCups, int money)
{
this.water = water;
this.milk = milk;
this.coffeeBeans = coffeeBeans;
this.disposableCups = disposableCups;
this.money = money;
}
void fill() {
System.out.println("Write how many ml of water you want to add: ");
water += input.nextInt();
System.out.println("Write how many ml of milk you want to add: ");
milk += input.nextInt();
System.out.println("Write how many grams of coffee beans you want to add: ");
coffeeBeans += input.nextInt();
System.out.println("Write how many disposable cups for coffee you want to add: ");
disposableCups += input.nextInt();
}
public void selectCoffee()
{
while (true)
{
System.out.println("What kind of coffee would you like to buy today?");
System.out.println(
" Please enter:\n" +
" 1 for espresso\n" +
" 2 for latte\n" +
" 3 for cappuccino\n" +
" 4 for a regular coffee\n" +
" back - to go back to main menu");
String choice = input.next();
try {
switch (choice) { //lets user choose what type of coffee to buy
case "1":
buy(new Espresso());
return;
case "2":
buy(new Latte());
return;
case "3":
buy(new Cappuccino());
return;
case "4":
buy(new RegularCoffee());
return;
case "back":
return;
default:
System.err.println("Please enter an option from the above");
}
}
catch (InsufficientResourcesException exception) {
System.err.println("Error buying coffee: " + exception.getLocalizedMessage());
}
}
}
public void buy(Coffee coffee) throws InsufficientResourcesException
{
if (coffee.getWaterCost() > water)
throw new InsufficientResourcesException("water", "ml", coffee.getWaterCost(), water);
if (coffee.getMilkCost() > milk)
throw new InsufficientResourcesException("milk", "ml", coffee.getMilkCost(), milk);
if (coffee.getCoffeeBeansCost() > coffeeBeans)
throw new InsufficientResourcesException("coffee beans", "g", coffee.getCoffeeBeansCost(), coffeeBeans);
if (disposableCups < 1)
throw new InsufficientResourcesException("disposable cups", "units", 1, disposableCups);
System.out.println("Buying 1 cup of " + coffee.getClass().getSimpleName());
water -= coffee.getWaterCost();
milk -= coffee.getMilkCost();
coffeeBeans -= coffee.getCoffeeBeansCost();
disposableCups--;
money += coffee.getMoneyCost();
}
public void takeMoney()
{
System.out.println("I gave you $" + money + ". The money tray is now empty.");
money = 0;
}
public void showResources()
{
System.out.println("The coffee machine has: ");
System.out.println(water + " ml of water");
System.out.println(milk + " ml of milk ");
System.out.println(coffeeBeans + " g of coffee beans ");
System.out.println(disposableCups + " disposable cups ");
System.out.println("$" + money + " of money");
}
public boolean mainMenu() { // Gives user option to decide what they want to do
System.out.println("Main Menu: " + "\n");
System.out.println("Please choose from the following options below");
System.out.println(
" To buy coffee - Enter buy\n" +
" To fill the machine - Enter fill\n" +
" To get cash from machine - Enter take\n" +
" To see remaining resources - Enter remaining\n" +
" To exit program - Enter exit");
String choice = input.next();
switch (choice) {
case "buy":
selectCoffee();
break;
case "fill":
fill();
break;
case "take":
takeMoney();
break;
case "remaining":
showResources();
break;
case "exit":
return false;
}
return true;
}
}
还有咖啡 classes:
public abstract class Coffee
{
private int waterCost;
private int milkCost;
private int coffeeBeansCost;
private int moneyCost;
protected Coffee(int waterCost, int milkCost, int coffeeBeansCost, int moneyCost)
{
this.waterCost = waterCost;
this.milkCost = milkCost;
this.coffeeBeansCost = coffeeBeansCost;
this.moneyCost = moneyCost;
}
public int getWaterCost()
{
return this.waterCost;
}
public int getMilkCost()
{
return this.milkCost;
}
public int getCoffeeBeansCost()
{
return this.coffeeBeansCost;
}
public int getMoneyCost()
{
return this.moneyCost;
}
}
public class Espresso extends Coffee
{
public Espresso()
{
super(250, 0, 16, 4);
}
}
public class Cappuccino extends Coffee
{
public Cappuccino()
{
super(200, 100, 12, 6);
}
}
public class Latte extends Coffee
{
public Latte()
{
super(350, 75, 20, 7);
}
}
public class RegularCoffee extends Coffee
{
public RegularCoffee()
{
super(200, 50, 15, 0);
}
}
最后但同样重要的是，异常 class:
public class InsufficientResourcesException extends Exception
{
private static final long serialVersionUID = 1L;
public InsufficientResourcesException(String whatResource, String unit, int required, int available)
{
super("Insufficient resources: required " + required + " " + unit + " of " + whatResource + " but available " + available + " " + unit);
}
}
拥有一个好的架构在软件中是最重要的。如果您的架构应用得当，错误就不太可能发生，即使发生也很容易修复。此外，更改具有良好架构的应用程序既简单又安全。
另一方面，糟糕的架构使得错误几乎是必然的，很难找到和修复，而且应用程序也不容易更改。
Question
我是 Java 的新手，我正在努力学习 can.The 我要解决的实际问题在上图中。如果我对问题的描述不够详细，请务必参考图片。我目前正在编写一个与买咖啡有关的 java 程序。我有一种方法可以计算购买咖啡的成本 (BuyCoffee) 和使用的资源量。也有不同类型的咖啡，每种咖啡使用不同数量的资源。我还有另一种方法可以计算咖啡售出后剩余的资源**(getRemainingResources)**。我在循环 getRemainingResources 方法时遇到问题。因此，当我购买一次咖啡时，我拥有的资源量就会减少。我有一种方法来填充这些资源。但每次我尝试再次购买相同的咖啡时，我所剩的资源量并没有减少。我的代码如下
import java.util.Scanner;
public class MethodsTest {
//global variable--starting quantity of resources in machine
static final int water = 400;
static final int milk = 540;
static final int coffeeBean = 120; // in g
static int disposableCups = 9;
static final int cost = 550; //in $
//global variable --refill quantity of resources in machine
static int fillWater, fillMilk, fillCoffeeBeans, fillDisposableCups;
//global variable -- remaining quantity of resources in machine
static int newRemCost, remCost, remWater, remMilk, remCoffeeBean, remDisposableCups;
static int espressoWater, espressoMilk, espressoCoffeeBeans, espressoCost; // Resources for espresso
static int latteWater, latteMilk, latteCoffeeBeans, latteCost;
static int cappuccinoWater, cappuccinoMilk, cappuccinoCoffeeBeans, cappuccinoCost;
static int regWater, regMilk, regCoffeeBeans, regCost; //Resources for regular coffees
static void FillCoffeeMachine() {
Scanner input = new Scanner(System.in);
System.out.println("Write how many ml of water you want to add: ");
fillWater = input.nextInt();
System.out.println("Write how many ml of milk you want to add: ");
fillMilk = input.nextInt();
System.out.println("Write how many grams of coffee beans you want to add: ");
fillCoffeeBeans = input.nextInt();
System.out.println("Write how many disposable cups of coffee you want to add: ");
fillDisposableCups = input.nextInt();
MainMenu();
}
static void BuyCoffee() { //method for buying coffee
disposableCups--;// always decreasing when coffee is sold
class TypesOfCoffee {
void Espresso() { //nested class, since there are different kind of coffee
espressoWater = 250;
espressoMilk = 0;
espressoCoffeeBeans = 16;
espressoCost = 4;
if (remWater > espressoWater && remMilk > espressoMilk && remCoffeeBean > espressoCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < espressoWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remCoffeeBean < espressoCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
void Latte() {
latteWater = 350;
latteMilk = 75;
latteCoffeeBeans = 20;
latteCost = 7;
if (remWater > latteWater && remMilk > latteMilk && remCoffeeBean > latteCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < latteWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remMilk < latteMilk) {
System.out.println("Sorry, not enough milk!");
disposableCups++;
} else if (remCoffeeBean < latteCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
void Cappuccino() {
cappuccinoWater = 200;
cappuccinoMilk = 100;
cappuccinoCoffeeBeans = 12;
cappuccinoCost = 6;
if (remWater > cappuccinoWater && remMilk > cappuccinoMilk && remCoffeeBean > cappuccinoCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < cappuccinoWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remMilk < cappuccinoMilk) {
System.out.println("Sorry, not enough milk!");
disposableCups++;
} else if (remCoffeeBean < cappuccinoCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
void regularCoffee() {
regWater = 200;
regMilk = 50;
regCoffeeBeans = 15;
regCost = 0;
if (remWater > regWater && remMilk > regMilk && remCoffeeBean > regCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < regWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remMilk < regMilk) {
System.out.println("Sorry, not enough milk!");
disposableCups++;
} else if (remCoffeeBean < regCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
}
Scanner input = new Scanner(System.in);
System.out.println("What kind of coffee would you like to buy today?");
System.out.println("""
Please enter:
1 for espresso
2 for latte
3 for cappuccino
4 for a regular coffee
back - to go back to main menu""");
String choice = input.next();
switch (choice) { //lets user choose what type of coffee to buy
case "1":
new TypesOfCoffee().Espresso();
break;
case "2":
new TypesOfCoffee().Latte();
break;
case "3":
new TypesOfCoffee().Cappuccino();
break;
case "4":
new TypesOfCoffee().regularCoffee();
break;
case "back":
MainMenu();
break;
default:
System.out.println("Please enter an option from the above");
}
MainMenu();
}
static void takeMoney() { //method to take the money
System.out.println("I gave you" + " " + "$" + remCost);
newRemCost = remCost;
MainMenu();
}
static void getRemainingResources() {
//TODO --has to loop..but it works only once
remDisposableCups = fillDisposableCups + disposableCups;
boolean found = remDisposableCups > 0; // true for coffee to be sold
while (found) {
remWater = water + fillWater - espressoWater - cappuccinoWater - latteWater;//
remMilk = milk + fillMilk - espressoMilk - cappuccinoMilk - latteMilk;
remCoffeeBean = coffeeBean + fillCoffeeBeans - espressoCoffeeBeans - cappuccinoCoffeeBeans - latteCoffeeBeans;
remCost = cost + espressoCost + cappuccinoCost + latteCost - newRemCost;
//found = remDisposableCups > 0 && remWater>=water && remMilk>=milk&&remCoffeeBean>=coffeeBean;
System.out.println("The coffee machine has: ");
System.out.println(remWater + " " + "ml of water");
System.out.println(remMilk + " " + "ml of milk ");
System.out.println(remCoffeeBean + " " + "g of coffee beans ");
System.out.println(remDisposableCups + " " + "disposable cups ");
System.out.println("$" + remCost + " " + "of money");
found = remDisposableCups < 0;
}
MainMenu();
}
static void MainMenu() { // Gives user option to decide what they want to do
Scanner input = new Scanner(System.in);
System.out.println("Main Menu: " + "\n");
System.out.println("Please choose from the following options below");
System.out.println("""
To buy coffee - Enter buy
To fill the machine - Enter fill
To get cash from machine - Enter take
To see remaining resources - Enter remaining
To exit program - Enter exit""");
String choice = input.next();
switch (choice) {
case "buy":
BuyCoffee();
break;
case "fill":
FillCoffeeMachine();
break;
case "take":
takeMoney();
break;
case "remaining":
getRemainingResources();
break;
case "exit":
System.exit(0);
break;
default:
MainMenu();//goes back to main menu if user types in an unknown value
}
}
public static void main(String[] args) {
MainMenu();
}
}
现在应该走了 但是还有其他错误（除了扫描仪，他们已经告诉过你了） 例如，如果不先“剩余”，你就不能买咖啡（还有：静态变量太多，没有使用 OO ...）。这只是一个例子。 我更正了您要求的错误的代码，但还有很多地方需要更改。
import java.util.Scanner;
public class MethodsTest {
//global variable--starting quantity of resources in machine
static final int water = 40000;
static final int milk = 54000;
static final int coffeeBean = 12000; // in g
static int disposableCups = 900;
static final int cost = 550; //in $
static int remCost = 550; //in $
//global variable --refill quantity of resources in machine
static int fillWater, fillMilk, fillCoffeeBeans, fillDisposableCups;
//global variable -- remaining quantity of resources in machine
static int newRemCost, remWater, remMilk, remCoffeeBean, remDisposableCups;
static int espressoWater, espressoMilk, espressoCoffeeBeans, espressoCost; // Resources for espresso
static int latteWater, latteMilk, latteCoffeeBeans, latteCost;
static int cappuccinoWater, cappuccinoMilk, cappuccinoCoffeeBeans, cappuccinoCost;
static int regWater, regMilk, regCoffeeBeans, regCost; //Resources for regular coffees
static void FillCoffeeMachine() {
Scanner input = new Scanner(System.in);
System.out.println("Write how many ml of water you want to add: ");
fillWater = input.nextInt();
System.out.println("Write how many ml of milk you want to add: ");
fillMilk = input.nextInt();
System.out.println("Write how many grams of coffee beans you want to add: ");
fillCoffeeBeans = input.nextInt();
System.out.println("Write how many disposable cups of coffee you want to add: ");
fillDisposableCups = input.nextInt();
MainMenu();
}
static void BuyCoffee() { //method for buying coffee
disposableCups--;// always decreasing when coffee is sold
class TypesOfCoffee {
void Espresso() { //nested class, since there are different kind of coffee
espressoWater = 250;
espressoMilk = 0;
espressoCoffeeBeans = 16;
espressoCost = 4;
if (remWater > espressoWater && remMilk > espressoMilk && remCoffeeBean > espressoCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < espressoWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remCoffeeBean < espressoCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
void Latte() {
latteWater = 350;
latteMilk = 75;
latteCoffeeBeans = 20;
latteCost = 7;
if (remWater > latteWater && remMilk > latteMilk && remCoffeeBean > latteCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < latteWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remMilk < latteMilk) {
System.out.println("Sorry, not enough milk!");
disposableCups++;
} else if (remCoffeeBean < latteCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
void Cappuccino() {
cappuccinoWater = 200;
cappuccinoMilk = 100;
cappuccinoCoffeeBeans = 12;
cappuccinoCost = 6;
if (remWater > cappuccinoWater && remMilk > cappuccinoMilk && remCoffeeBean > cappuccinoCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < cappuccinoWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remMilk < cappuccinoMilk) {
System.out.println("Sorry, not enough milk!");
disposableCups++;
} else if (remCoffeeBean < cappuccinoCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
void regularCoffee() {
regWater = 200;
regMilk = 50;
regCoffeeBeans = 15;
regCost = 0;
if (remWater > regWater && remMilk > regMilk && remCoffeeBean > regCoffeeBeans) {
System.out.println("I have enough resources, making you a coffee!");
} else if (remWater < regWater) {
System.out.println("Sorry, not enough water!");
disposableCups++;
} else if (remMilk < regMilk) {
System.out.println("Sorry, not enough milk!");
disposableCups++;
} else if (remCoffeeBean < regCoffeeBeans) {
System.out.println("Sorry, not enough coffee beans!");
disposableCups++;
} else
disposableCups++;
}
}
Scanner input = new Scanner(System.in);
System.out.println("What kind of coffee would you like to buy today?");
System.out.println("""
Please enter:
1 for espresso
2 for latte
3 for cappuccino
4 for a regular coffee
back - to go back to main menu""");
String choice = input.next();
switch (choice) { //lets user choose what type of coffee to buy
case "1":
new TypesOfCoffee().Espresso();
break;
case "2":
new TypesOfCoffee().Latte();
break;
case "3":
new TypesOfCoffee().Cappuccino();
break;
case "4":
new TypesOfCoffee().regularCoffee();
break;
case "back":
MainMenu();
break;
default:
System.out.println("Please enter an option from the above");
}
MainMenu();
}
static void takeMoney() { //method to take the money
System.out.println("I gave you" + " " + "$" + remCost);
newRemCost = remCost;
MainMenu();
}
static void getRemainingResources() {
//TODO --has to loop..but it works only once
remDisposableCups = fillDisposableCups + disposableCups;
boolean found = remDisposableCups > 0; // true for coffee to be sold
while (found) {
remWater = water + fillWater - espressoWater - cappuccinoWater - latteWater;//
remMilk = milk + fillMilk - espressoMilk - cappuccinoMilk - latteMilk;
remCoffeeBean = coffeeBean + fillCoffeeBeans - espressoCoffeeBeans - cappuccinoCoffeeBeans - latteCoffeeBeans;
remCost = remCost + espressoCost + cappuccinoCost + latteCost - newRemCost;
espressoCost = 0;
cappuccinoCost = 0;
latteCost = 0;
//found = remDisposableCups > 0 && remWater>=water && remMilk>=milk&&remCoffeeBean>=coffeeBean;
System.out.println("The coffee machine has: ");
System.out.println(remWater + " " + "ml of water");
System.out.println(remMilk + " " + "ml of milk ");
System.out.println(remCoffeeBean + " " + "g of coffee beans ");
System.out.println(remDisposableCups + " " + "disposable cups ");
System.out.println("$" + remCost + " " + "of money");
found = remDisposableCups < 0;
}
MainMenu();
}
static void MainMenu() { // Gives user option to decide what they want to do
Scanner input = new Scanner(System.in);
System.out.println("Main Menu: " + "\n");
System.out.println("Please choose from the following options below");
System.out.println("""
To buy coffee - Enter buy
To fill the machine - Enter fill
To get cash from machine - Enter take
To see remaining resources - Enter remaining
To exit program - Enter exit""");
String choice = input.next();
switch (choice) {
case "buy":
BuyCoffee();
break;
case "fill":
FillCoffeeMachine();
break;
case "take":
takeMoney();
break;
case "remaining":
getRemainingResources();
break;
case "exit":
System.exit(0);
break;
default:
MainMenu();//goes back to main menu if user types in an unknown value
}
}
public static void main(String[] args) {
MainMenu();
}
}
你写的代码非常复杂，所以你看不出错误在哪里。一些评论：
- Java 是一种面向对象 (OO) 的语言。 OO 范式围绕创建 classes 及其对象、继承和多态性（从父 classes 继承行为，但在每个子 class 中表现不同）。
- 您的代码看起来像是在尝试像旧版本的 Basic 或 Macro Assembler 一样重新创建结构化编程，只是遵守 Java 的语法。您需要真正了解 OO 编程的工作原理，因此首先尝试查找一些相关教程。
- 不要把所有的东西都放在一起class。尝试识别您的应用程序中的不同实体。例如：CoffeMachine、Coffee、Espresso、Latte、RegularCoffee，...为每个已识别的实体创建一个 class。彼此相似的 classes 可能应该是继承的一部分，例如 Espresso、Lattte 等应该继承更通用的 class Coffee（A 继承 B，当你可以说“A is a有点 B").
- 不要使用静态变量（除非有很好的理由，但这种情况很少见）。当您创建它们的对象时，让每个 class 都有自己的实例属性：remainingWater、remainingMilk 等是对象 CoffeeMachine 的属性。它们不是全球性的东西。
- 不要使用 C 或 Basic 中的子例程等静态方法。相反，创建 classes 的对象并调用它们的实例方法。
- 不要像在 Basic 或 Assembler 中那样使用跳转和标签。相反，在循环中调用对象的方法并在必要时中断循环。
- 如果您在应用程序中检测到错误，请使用 Java 的异常机制 - 抛出异常并让调用者处理错误。
- 方法名以Java中的小写字母开头（这是公认的约定，不是句法规则）。
我根据上述原则为您的应用程序创建了不同的设计，因此请先从教程中学习面向对象编程的基础知识，然后将以下代码与您的代码进行比较，看看有什么不同。
Main class（主菜单循环的入口点）：
public class Main
{
public static void main(String[] args)
{
new Main().run();
}
void run()
{
CoffeeMachine coffeeMachine = new CoffeeMachine(400, 540, 120, 9, 550);
while (coffeeMachine.mainMenu()); // loops until mainMenu returns false
}
}
咖啡机：
import java.util.Scanner;
public class CoffeeMachine
{
private Scanner input = new Scanner(System.in);
private int water;
private int milk;
private int coffeeBeans;
private int disposableCups;
private int money;
public CoffeeMachine(int water, int milk, int coffeeBeans, int disposableCups, int money)
{
this.water = water;
this.milk = milk;
this.coffeeBeans = coffeeBeans;
this.disposableCups = disposableCups;
this.money = money;
}
void fill() {
System.out.println("Write how many ml of water you want to add: ");
water += input.nextInt();
System.out.println("Write how many ml of milk you want to add: ");
milk += input.nextInt();
System.out.println("Write how many grams of coffee beans you want to add: ");
coffeeBeans += input.nextInt();
System.out.println("Write how many disposable cups for coffee you want to add: ");
disposableCups += input.nextInt();
}
public void selectCoffee()
{
while (true)
{
System.out.println("What kind of coffee would you like to buy today?");
System.out.println(
" Please enter:\n" +
" 1 for espresso\n" +
" 2 for latte\n" +
" 3 for cappuccino\n" +
" 4 for a regular coffee\n" +
" back - to go back to main menu");
String choice = input.next();
try {
switch (choice) { //lets user choose what type of coffee to buy
case "1":
buy(new Espresso());
return;
case "2":
buy(new Latte());
return;
case "3":
buy(new Cappuccino());
return;
case "4":
buy(new RegularCoffee());
return;
case "back":
return;
default:
System.err.println("Please enter an option from the above");
}
}
catch (InsufficientResourcesException exception) {
System.err.println("Error buying coffee: " + exception.getLocalizedMessage());
}
}
}
public void buy(Coffee coffee) throws InsufficientResourcesException
{
if (coffee.getWaterCost() > water)
throw new InsufficientResourcesException("water", "ml", coffee.getWaterCost(), water);
if (coffee.getMilkCost() > milk)
throw new InsufficientResourcesException("milk", "ml", coffee.getMilkCost(), milk);
if (coffee.getCoffeeBeansCost() > coffeeBeans)
throw new InsufficientResourcesException("coffee beans", "g", coffee.getCoffeeBeansCost(), coffeeBeans);
if (disposableCups < 1)
throw new InsufficientResourcesException("disposable cups", "units", 1, disposableCups);
System.out.println("Buying 1 cup of " + coffee.getClass().getSimpleName());
water -= coffee.getWaterCost();
milk -= coffee.getMilkCost();
coffeeBeans -= coffee.getCoffeeBeansCost();
disposableCups--;
money += coffee.getMoneyCost();
}
public void takeMoney()
{
System.out.println("I gave you $" + money + ". The money tray is now empty.");
money = 0;
}
public void showResources()
{
System.out.println("The coffee machine has: ");
System.out.println(water + " ml of water");
System.out.println(milk + " ml of milk ");
System.out.println(coffeeBeans + " g of coffee beans ");
System.out.println(disposableCups + " disposable cups ");
System.out.println("$" + money + " of money");
}
public boolean mainMenu() { // Gives user option to decide what they want to do
System.out.println("Main Menu: " + "\n");
System.out.println("Please choose from the following options below");
System.out.println(
" To buy coffee - Enter buy\n" +
" To fill the machine - Enter fill\n" +
" To get cash from machine - Enter take\n" +
" To see remaining resources - Enter remaining\n" +
" To exit program - Enter exit");
String choice = input.next();
switch (choice) {
case "buy":
selectCoffee();
break;
case "fill":
fill();
break;
case "take":
takeMoney();
break;
case "remaining":
showResources();
break;
case "exit":
return false;
}
return true;
}
}
还有咖啡 classes:
public abstract class Coffee
{
private int waterCost;
private int milkCost;
private int coffeeBeansCost;
private int moneyCost;
protected Coffee(int waterCost, int milkCost, int coffeeBeansCost, int moneyCost)
{
this.waterCost = waterCost;
this.milkCost = milkCost;
this.coffeeBeansCost = coffeeBeansCost;
this.moneyCost = moneyCost;
}
public int getWaterCost()
{
return this.waterCost;
}
public int getMilkCost()
{
return this.milkCost;
}
public int getCoffeeBeansCost()
{
return this.coffeeBeansCost;
}
public int getMoneyCost()
{
return this.moneyCost;
}
}
public class Espresso extends Coffee
{
public Espresso()
{
super(250, 0, 16, 4);
}
}
public class Cappuccino extends Coffee
{
public Cappuccino()
{
super(200, 100, 12, 6);
}
}
public class Latte extends Coffee
{
public Latte()
{
super(350, 75, 20, 7);
}
}
public class RegularCoffee extends Coffee
{
public RegularCoffee()
{
super(200, 50, 15, 0);
}
}
最后但同样重要的是，异常 class:
public class InsufficientResourcesException extends Exception
{
private static final long serialVersionUID = 1L;
public InsufficientResourcesException(String whatResource, String unit, int required, int available)
{
super("Insufficient resources: required " + required + " " + unit + " of " + whatResource + " but available " + available + " " + unit);
}
}
拥有一个好的架构在软件中是最重要的。如果您的架构应用得当，错误就不太可能发生，即使发生也很容易修复。此外，更改具有良好架构的应用程序既简单又安全。
另一方面，糟糕的架构使得错误几乎是必然的，很难找到和修复，而且应用程序也不容易更改。