Question

退出菜单后，如何通过选择“4：退出”让系统再次提示输入其他帐户ID

        Scanner input = new Scanner(System.in);
        System.out.print("Enter an id: ");
        int ID = input.nextInt();


        System.out.println("\nMain Menu ");
        System.out.println("1. Check balance");
        System.out.println("2. Withdraw");
        System.out.println("3. Deposit");
        System.out.println("4. Exit");
        System.out.println("Enter a choice: ");
        int choice = input.nextInt();

    switch (choice ) {  

        case 1: 
        System.out.println("The balance is: " + accountArray[ID].getBalance());
        break;
        case 2: 
        System.out.println("Enter amount to withdraw: ");
        double withdrawAmount = input.nextDouble();
        accountArray[ID].withdraw(withdrawAmount);
        break;
        case 3: 
        System.out.println("Enter amount to deposit: ");
        double depositAmount = input.nextDouble();
        accountArray[ID].deposit(depositAmount);
        break; 
        case 4: 
        System.out.println("Thank you for banking with us");    
        break;
        }

System.out.println（“The Balance is：”+ accountArray [ID] .getBalance（））; }

Answer 1

使用while(true)包围所有内容（可能会将扫描仪声明保留在外面，因为它始终是相同的。）

Answer 2

您可以使用while循环：

int choice = 0;

while (choice != 4) {
    System.out.print("Enter an id: ");
    int ID = input.nextInt();
    ...
    int choice = input.nextInt();
    ...
}

修改

int choice = 0; while (true) { System.out.print("Enter an id: "); int ID = input.nextInt(); while(choice != 4) { ... int choice = input.nextInt(); ... } }

Answer 3

由于您希望用户能够继续查询其他帐户，因此嵌套循环以便在输入“4”时返回到外部循环，提示他们输入新的ID：

    Scanner input = new Scanner(System.in);
    int ID;
    while (true) {
      System.out.print("Enter an id: ");
      ID = input.nextInt();

      int choice = 0;
      while (chioce != 4) {
        System.out.println("\nMain Menu ");
        System.out.println("1. Check balance");
        System.out.println("2. Withdraw");
        System.out.println("3. Deposit");
        System.out.println("4. Exit");
        System.out.println("Enter a choice: ");
        choice = input.nextInt();

        switch (choice ) {  
           case 1: 
           System.out.println("The balance is: " + accountArray[ID].getBalance());
           break;
           case 2: 
           System.out.println("Enter amount to withdraw: ");
           double withdrawAmount = input.nextDouble();
           accountArray[ID].withdraw(withdrawAmount);
           break;
           case 3: 
           System.out.println("Enter amount to deposit: ");
           double depositAmount = input.nextDouble();
           accountArray[ID].deposit(depositAmount);
           break; 
           case 4: 
           System.out.println("Thank you for banking with us");    
           break;
        }

        System.out.println("The Balance is: " + accountArray[ID].getBalance());
      }
    }

如果您希望用户能够终止程序，请将外部循环条件从true更改为类似于内部循环的内容，并相应地提示它们，即“输入id或-1退出”。

切换语句JAVA提示新ID

3 个答案: