java - 当用户为我的自定义异常输入小于 0 的数字时，无法查明问题

Question

似乎无法弄清楚这一点。如果用户输入无效余额，我如何重新提示他们再次输入余额并继续我的程序？

  //EDITED STILL WONT WORK PROPERLY
 boolean again;
    while(again = true) 
    {
        try {

            // pass object to printwriter and pw to write to the file
            pw = new PrintWriter(fw);

            System.out.print("Input beginnning balance: ");
            balance = input.nextDouble();
            again = false;
            // pass user input to object
            AccountWithException acctException = new AccountWithException(fullName, balance, id, RATE);
            again = false;

            System.out.println(acctException.toString());

            // copy object to created file
            pw.println(acctException.toString());
            again = false; 

        // custom exception
        } catch (InvalidBalanceException e) {
            System.out.println(e.getMessage());
        } catch(FileNotFoundException e) {
            System.out.println(e.getMessage());
        } finally {
            pw.close();

Answer 1

您可以抛出无效余额异常并在catch block 中捕获它，如下所示

try {

        // pass object to printwriter and pw to write to the file
        pw = new PrintWriter(fw);

        // pass user input to object
        AccountWithException acctException = new AccountWithException(fullName, balance, id, RATE);

        System.out.println(acctException.toString());

        // copy object to created file
        pw.println(acctException.toString());
throw new InvalidBalanceException ();

        // custom exception if balance < 0
    } catch (InvalidBalanceException e) {
        System.out.println(e.getMessage());
        System.out.println("Re-enter balance: ");
        balance = input.nextDouble();
    } catch(FileNotFoundException e) {
        System.out.println(e.getMessage());
    } finally {
        System.out.println("Text file closed, program complete...");
        pw.close();
    }