需要将用户输入存储到arraylist中并保存到TXT文件中，以便一旦要求就可以向后拉

Question

我试图从菜单中阅读我的用户，然后进行选择1(添加产品名称，商店名称，购买日期和成本(，选项2显示ArrayList，购买对象已被输入，并且选项3退出了程序，并感谢用户使用我的程序，同时有例外，以确保用户不输入和有效的条目。现在，我需要能够存储到txt文件，并有能力将其拉回以进行审查或修改。

我构建了菜单，并且我相信我已经正确设置了我的arraylist以适合适当的用户输入，每个字符串的方法都将输入和例外，以确保输入有效

public static void main(String[] args) throws Exception {
    //Create menu options 
    TheMenu();
}
public static void TheMenu() {
    Scanner input = new Scanner(System.in);
    String purchase[] = new String[4];

    int option;
    do { // loop until Exit (option 3) is selected
        System.out.println("nMenu Options");
        System.out.println("n1 Add a purchase");
        System.out.println("n2 Display a purchase");
        System.out.println("n3 Exit");
        option = input.nextInt();
        if (option == 1) {
            displayPurchaseObjects(purchase);
        }
        if (option == 2) {
            System.out.println();
        }
        while (option == 3) 
            System.out.println("Thank you for using purchase programmer!");
        System.exit(3); 

    //Create a list to store Purchase objects
    ArrayList<String> displayPurchaseObjects = new ArrayList<>();
    while(input.hasNext()) {
        System.out.println("Enter the product name "); 
        String productName = input.next();
        System.out.print("Enter the store name"); 
        String storeName = input.next();
        System.out.println("Enter the purchase date (i.e. 06/30/2019) ");
        int purchaseDate = input.nextInt();
        System.out.println("Enter the cost ");
        double cost = input.nextDouble();
    }
}

}

    public void  productName(String productName) { 
        try {
            for(int i = 1; i < productName.length(); i++) { 
        }       
    }
        catch(Exception e) {
            System.out.println("Please enter a product name ");         
        }
    }
    public void storeName(String storeName) {
        try {
            for(int i = 1; i < storeName.length(); i++) { 
        }       
    }
        catch(Exception e) {
            System.out.println("Please enter a store name");
        }
    }
    public void purchaseDate(String date) {
        DateTimeFormatter format = DateTimeFormatter.ofPattern(date);
        try {
            format.parse(date);
        }
        catch(Exception e) {
            System.out.println("Invalid date");
        }
    }
    public void cost(double newCost) 
         throws InputMismatchException{
        double cost;
        if(newCost >= 1)
            cost = newCost;
        else 
            throw new InputMismatchException("Cost must be a integer and more the $0 ");
    }

我正在收到汇编错误，因为"}"我找不到原因，并且该程序应该允许我进行选择(1,2或3(，并且应该能够将我的购买对象添加到我的" displayPurchaseObjects" arrayList

Answer 1

如果我清楚地理解了您的问题，那么手头的问题是编译错误 - 找不到"}"。

在您的代码中，您错过了此后的"}" -

do { // loop until Exit (option 3) is selected
    System.out.println("nMenu Options");
    System.out.println("n1 Add a purchase");
    System.out.println("n2 Display a purchase");
    System.out.println("n3 Exit");
    option = input.nextInt();
    if (option == 1) {
        displayPurchaseObjects(purchase);
    }
    if (option == 2) {
        System.out.println();
    }
} while (option == 3);
System.out.println("Thank you for using purchase programmer!");
// Non zero exit code is only for abnormal termination. Use 0.
System.exit(0);