【发布时间】：2020-05-05 07:05:33
【问题描述】：
我已经尝试了几个小时，但我无法在循环中管理异常！ 基本上我希望在出现错误时激活循环！ Ps：这是一个迷你餐厅，因为我是初学者，所以我正在做Java培训！
这里是我想把异常放在代码的不同部分重做的地方：
do {
System.out.println("\nMain menu:\n");
for (int i = 0; i < mainMenu.length; i++) {
int menuNumber = i + 1;
System.out.println(menuNumber + ": "+ mainMenu[i]);
}
try {
System.out.print("The number of your choice: ");
mainMenuChoice.add(scanInt.nextInt()); // exeption here
if(mainMenuChoice.get(mainI) > mainMenu.length || mainMenuChoice.get(mainI) <= 0) {
mainWhilePass = false;
mainMenuChoice.remove(mainI);
} else {
mainWhilePass = true;
}
} catch (Exception e) {
System.err.println("Error: " + e);
}
} while (!mainWhilePass);
这里是完整的代码：
import java.util.ArrayList;
import java.util.Scanner;
public class McHouseCommand {
public static void main(String[] args) {
Scanner scanInt = new Scanner(System.in);
Scanner scanLine = new Scanner(System.in);
String mainMenu[] = {"McBurger", "McTrio", "Fries" , "Nothing"};
String drinkMenu[] = {"Coca", "Pepsi", "Coffe", "Nothing"};
String sauceMenu[] = {"Ketchup", "Moutarde", "Mayo", "Nothing"};
int mainI = -1;
int drinkI = -1;
int sauceI = -1;
ArrayList<Integer> mainMenuChoice = new ArrayList<Integer>();
ArrayList<Integer> drinkMenuChoice = new ArrayList<Integer>();
ArrayList<Integer> sauceMenuChoice = new ArrayList<Integer>();
boolean mainRetake, drinkRetake, sauceRetake;
boolean mainWhilePass = false, drinkWhilePass = false, sauceWhilePass = false;
String mainRetakeAnswer, drinkRetakeAnswer, sauceRetakeAnswer;
System.out.println("Welcome to McHouse ! "+"\n");
/* Main Menu *//* Main Menu *//* Main Menu *//* Main Menu *//* Main Menu *//* Main Menu *//* Main Menu *//* Main Menu *//* Main Menu */
do {
mainI ++;
do {
System.out.println("\nMain menu:\n");
for (int i = 0; i < mainMenu.length; i++) {
int menuNumber = i + 1;
System.out.println(menuNumber + ": "+ mainMenu[i]);
}
try {
System.out.print("The number of your choice: ");
mainMenuChoice.add(scanInt.nextInt()); // exeption here
if(mainMenuChoice.get(mainI) > mainMenu.length || mainMenuChoice.get(mainI) <= 0) {
mainWhilePass = false;
mainMenuChoice.remove(mainI);
} else {
mainWhilePass = true;
}
} catch (Exception e) {
System.err.println("Error: " + e);
}
} while (!mainWhilePass);
do {
System.out.print("\n[Yes | No] Do you want to retake: ");
mainRetakeAnswer = scanLine.nextLine();
} while (!mainRetakeAnswer.equalsIgnoreCase("yes") && !mainRetakeAnswer.equalsIgnoreCase("no"));
if (mainRetakeAnswer.equalsIgnoreCase("yes")) {
mainRetake = true;
} else {
mainRetake = false;
}
} while (mainRetake);
System.out.println("");
/* Drink Menu *//* Drink Menu *//* Drink Menu *//* Drink Menu *//* Drink Menu *//* Drink Menu *//* Drink Menu *//* Drink Menu */
do {
drinkI ++;
do {
System.out.println("\nDrink menu:\n");
for (int i = 0; i < drinkMenu.length; i++) {
int menuNumber = i + 1;
System.out.println(menuNumber + ": "+ drinkMenu[i]);
}
System.out.print("The number of your choice: ");
drinkMenuChoice.add(scanInt.nextInt());
if(drinkMenuChoice.get(drinkI) > drinkMenu.length || drinkMenuChoice.get(drinkI) <= 0) {
drinkWhilePass = false;
drinkMenuChoice.remove(drinkI);
} else {
drinkWhilePass = true;
}
} while (!drinkWhilePass);
do {
System.out.print("\n[Yes | No] Do you want to retake: ");
drinkRetakeAnswer = scanLine.nextLine();
} while (!drinkRetakeAnswer.equalsIgnoreCase("yes") && !drinkRetakeAnswer.equalsIgnoreCase("no"));
if (drinkRetakeAnswer.equalsIgnoreCase("yes")) {
drinkRetake = true;
} else {
drinkRetake = false;
}
} while (drinkRetake);
System.out.println("");
/* Sauce Menu *//* Sauce Menu *//* Sauce Menu *//* Sauce Menu *//* Sauce Menu *//* Sauce Menu *//* Sauce Menu *//* Sauce Menu */
do {
sauceI ++;
do {
System.out.println("\nSauce menu:\n");
for (int i = 0; i < sauceMenu.length; i++) {
int menuNumber = i + 1;
System.out.println(menuNumber + ": "+ sauceMenu[i]);
}
System.out.print("The number of your choice: ");
sauceMenuChoice.add(scanInt.nextInt());
if(sauceMenuChoice.get(sauceI) > sauceMenu.length || sauceMenuChoice.get(sauceI) <= 0) {
sauceWhilePass = false;
sauceMenuChoice.remove(sauceI);
} else {
sauceWhilePass = true;
}
} while (!sauceWhilePass);
do {
System.out.print("\n[Yes | No] Do you want to retake: ");
sauceRetakeAnswer = scanLine.nextLine();
} while (!sauceRetakeAnswer.equalsIgnoreCase("yes") && !sauceRetakeAnswer.equalsIgnoreCase("no"));
if (sauceRetakeAnswer.equalsIgnoreCase("yes")) {
sauceRetake = true;
} else {
sauceRetake = false;
}
} while (sauceRetake);
/* What did you buy *//* What did you buy *//* What did you buy *//* What did you buy *//* What did you buy *//* What did you buy */
System.out.println("");
System.out.println("Great! ");
System.out.println("You purchached: \n");
System.out.println("Main Menu");
for(int i = 0; i < mainMenuChoice.size();i++) {
int r = mainMenuChoice.get(i) - 1;
System.out.println( (i+ 1) + "| "+ mainMenu[r]);
}
System.out.println("");
System.out.println("Drink");
for(int i = 0; i < drinkMenuChoice.size();i++) {
int r = drinkMenuChoice.get(i) - 1;
System.out.println( (i+ 1) + "| "+ drinkMenu[r]);
}
System.out.println("");
System.out.println("Sauce");
for(int i = 0; i < sauceMenuChoice.size();i++) {
int r = sauceMenuChoice.get(i) - 1;
System.out.println( (i+ 1) + "| "+ sauceMenu[r]);
}
/* Program end *//* Program end *//* Program end *//* Program end *//* Program end *//* Program end *//* Program end */
scanLine.close();
scanInt.close();
System.out.println("\n\nProgarm end");
}
}
这是最终代码：
import java.util.Scanner;
public class McHouseCommand {
public static void main(String[] args) {
Scanner scanInt = new Scanner(System.in);
Scanner scanLine = new Scanner(System.in);
String mainMenu[] = {"McBurger", "McTrio", "Fries" , "Nothing"};
String drinkMenu[] = {"Coca", "Pepsi", "Coffe", "Nothing"};
String sauceMenu[] = {"Ketchup", "Moutarde", "Mayo", "Nothing"};
int mainI = -1;
int drinkI = -1;
int sauceI = -1;
ArrayList<Integer> mainMenuChoice = new ArrayList<Integer>();
ArrayList<Integer> drinkMenuChoice = new ArrayList<Integer>();
ArrayList<Integer> sauceMenuChoice = new ArrayList<Integer>();
boolean mainRetake, drinkRetake, sauceRetake;
boolean mainWhilePass = false, drinkWhilePass = false, sauceWhilePass = false;
String mainRetakeAnswer, drinkRetakeAnswer, sauceRetakeAnswer;
System.out.println("Welcome to McHouse ! "+"\n");
/* Main Menu *//* Main Menu *//* Main Menu *//* Main Menu *//* Main Menu *//* Main Menu *//* Main Menu *//* Main Menu *//* Main Menu */
do {
mainI ++;
do {
System.out.println("\nMain menu:\n");
for (int i = 0; i < mainMenu.length; i++) {
int menuNumber = i + 1;
System.out.println(menuNumber + ": "+ mainMenu[i]);
}
try {
System.out.print("The number of your choice: ");
if (scanInt.hasNextInt()) {
mainMenuChoice.add(scanInt.nextInt()); // exeption here
if(mainMenuChoice.get(mainI) > mainMenu.length || mainMenuChoice.get(mainI) <= 0) {
mainWhilePass = false;
mainMenuChoice.remove(mainI);
} else {
mainWhilePass = true;
}
} else {
System.err.print("Not valid choice: " + scanInt.next());
mainI -= 1;
}
} catch (Exception e) {
System.err.println("Error: " + e);
scanInt.next();
}
} while (!mainWhilePass);
do {
System.out.print("\n[Yes | No] Do you want to retake: ");
mainRetakeAnswer = scanLine.nextLine();
} while (!mainRetakeAnswer.equalsIgnoreCase("yes") && !mainRetakeAnswer.equalsIgnoreCase("no"));
if (mainRetakeAnswer.equalsIgnoreCase("yes")) {
mainRetake = true;
} else {
mainRetake = false;
}
} while (mainRetake);
System.out.println("");
/* Drink Menu *//* Drink Menu *//* Drink Menu *//* Drink Menu *//* Drink Menu *//* Drink Menu *//* Drink Menu *//* Drink Menu */
do {
drinkI ++;
do {
System.out.println("\nDrink menu:\n");
for (int i = 0; i < drinkMenu.length; i++) {
int menuNumber = i + 1;
System.out.println(menuNumber + ": "+ drinkMenu[i]);
}
System.out.print("The number of your choice: ");
drinkMenuChoice.add(scanInt.nextInt());
if(drinkMenuChoice.get(drinkI) > drinkMenu.length || drinkMenuChoice.get(drinkI) <= 0) {
drinkWhilePass = false;
drinkMenuChoice.remove(drinkI);
} else {
drinkWhilePass = true;
}
} while (!drinkWhilePass);
do {
System.out.print("\n[Yes | No] Do you want to retake: ");
drinkRetakeAnswer = scanLine.nextLine();
} while (!drinkRetakeAnswer.equalsIgnoreCase("yes") && !drinkRetakeAnswer.equalsIgnoreCase("no"));
if (drinkRetakeAnswer.equalsIgnoreCase("yes")) {
drinkRetake = true;
} else {
drinkRetake = false;
}
} while (drinkRetake);
System.out.println("");
/* Sauce Menu *//* Sauce Menu *//* Sauce Menu *//* Sauce Menu *//* Sauce Menu *//* Sauce Menu *//* Sauce Menu *//* Sauce Menu */
do {
drinkI ++;
do {
System.out.println("\nDrink menu:\n");
for (int i = 0; i < drinkMenu.length; i++) {
int menuNumber = i + 1;
System.out.println(menuNumber + ": "+ drinkMenu[i]);
}
try {
System.out.print("The number of your choice: ");
if (scanInt.hasNextInt()) {
drinkMenuChoice.add(scanInt.nextInt()); // exeption here
if(drinkMenuChoice.get(drinkI) > drinkMenu.length || drinkMenuChoice.get(drinkI) <= 0) {
drinkWhilePass = false;
drinkMenuChoice.remove(drinkI);
} else {
drinkWhilePass = true;
}
} else {
System.err.print("Not valid choice: " + scanInt.next());
drinkI -= 1;
}
} catch (Exception e) {
System.err.println("Error: " + e);
scanInt.next();
}
} while (!drinkWhilePass);
do {
System.out.print("\n[Yes | No] Do you want to retake: ");
drinkRetakeAnswer = scanLine.nextLine();
} while (!drinkRetakeAnswer.equalsIgnoreCase("yes") && !drinkRetakeAnswer.equalsIgnoreCase("no"));
if (drinkRetakeAnswer.equalsIgnoreCase("yes")) {
drinkRetake = true;
} else {
drinkRetake = false;
}
} while (drinkRetake);
System.out.println("");
/* What did you buy *//* What did you buy *//* What did you buy *//* What did you buy *//* What did you buy *//* What did you buy */
do {
sauceI ++;
do {
System.out.println("\nSauce menu:\n");
for (int i = 0; i < sauceMenu.length; i++) {
int menuNumber = i + 1;
System.out.println(menuNumber + ": "+ sauceMenu[i]);
}
try {
System.out.print("The number of your choice: ");
if (scanInt.hasNextInt()) {
sauceMenuChoice.add(scanInt.nextInt()); // exeption here
if(sauceMenuChoice.get(sauceI) > sauceMenu.length || sauceMenuChoice.get(sauceI) <= 0) {
sauceWhilePass = false;
sauceMenuChoice.remove(sauceI);
} else {
sauceWhilePass = true;
}
} else {
System.err.print("Not valid choice: " + scanInt.next());
sauceI -= 1;
}
} catch (Exception e) {
System.err.println("Error: " + e);
scanInt.next();
}
} while (!sauceWhilePass);
do {
System.out.print("\n[Yes | No] Do you want to retake: ");
sauceRetakeAnswer = scanLine.nextLine();
} while (!sauceRetakeAnswer.equalsIgnoreCase("yes") && !sauceRetakeAnswer.equalsIgnoreCase("no"));
if (sauceRetakeAnswer.equalsIgnoreCase("yes")) {
sauceRetake = true;
} else {
sauceRetake = false;
}
} while (sauceRetake);
System.out.println("");
/* Program end *//* Program end *//* Program end *//* Program end *//* Program end *//* Program end *//* Program end */
scanLine.close();
scanInt.close();
System.out.println("\n\nProgarm end");
}
}
【问题讨论】：
-
当您说您希望循环“在出现错误时激活”是什么意思？你想抛出或捕获异常吗？请修正代码的缩进并删除任何多余的空行
-
while 被触发，但不再要求用户输入答案！它只是无限循环！
-
仍然没有解释你想如何处理异常。并且不要在评论中解释，而是更新您的问题。
-
我已经修改了代码，以便您可以更好地理解它，但是当我执行此代码时，它只会创建一个无限循环！ ='(
-
我仍然没有真正得到你想要做什么，但我看到你处理响应的逻辑很复杂。不是将响应添加到列表中，而是 mainMenuChoice.add(scanInt.nextInt());然后获取它并可能将其从列表中删除，您应该将其读入您验证的本地 int 变量，如果可以，则将其添加到列表中。所以
int choice = scanInt.nextInt();然后验证并添加choice
标签： java while-loop try-catch do-while