java - 我如何处理空的 jXDatePicker？

Question

我有一个 swing 表单，其中包含 jXDatePicker 来捕获日期。如果未在 jXDatePicker 中选择日期，则尝试将日期插入数据库时​​会引发错误。以下是我在 Netbeans 中遇到的错误: 线程“AWT-EventQueue-0”中出现异常 java.lang.NullPointerException。下面是给我错误的代码:

    String dateOpened, dateOfLastUpdate, dateOf1stDelinquency, dateOfLastPayment,  dateClosed;
    DateFormat format = new SimpleDateFormat("yyyy-MM-dd");
    dateOpened = format.format(jXDatePicker7.getDate());
    dateOfLastUpdate = format.format(jXDatePicker2.getDate());
    dateOf1stDelinquency = format.format(jXDatePicker4.getDate());
    dateOfLastPayment = format.format(jXDatePicker5.getDate());
    dateClosed = format.format(jXDatePicker6.getDate());

String query2 = "insert into ACCOUNT (ACCOUNT_NUMBER,DATE_CLOSED ,DELINQUENCY_DATE,     UPDATE_DATE,AMOUNT_OWING,"
                + "BALANCE,PAYMENT_HISTORY,ACCOUNT_STATUS,MONTHLY_PAYMENT,TERMS_DURATION,PRINCIPAL,CREDIT_LIMIT,"
                + "DATE_OPENED,PORTIFOLIO_TYPE,ACCOUNT_TYPE,NATIONAL_ID,COSIGNER_NATIONAL_ID)"
                + "values (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)";
        PreparedStatement preparedStatement2 = con.prepareStatement(query2);
        preparedStatement2.setString(1, acc_no);
        preparedStatement2.setString(2, dateClosed);
        preparedStatement2.setString(3, dateOf1stDelinquency);
        preparedStatement2.setString(4, dateOfLastUpdate);
        preparedStatement2.setDouble(5, amount_owing);
        preparedStatement2.setDouble(6, current_balance);
        preparedStatement2.setString(7, payment_history);
        preparedStatement2.setString(8, account_status);
        preparedStatement2.setDouble(9, monthly_payment);
        preparedStatement2.setDouble(10, terms_duration);
        preparedStatement2.setDouble(11, principal);
        preparedStatement2.setDouble(12, credit_limit);
        preparedStatement2.setString(13, dateOpened);
        preparedStatement2.setString(14, portfolio_type);
        preparedStatement2.setString(15, acc_type);
        preparedStatement2.setString(16, national_id);
        preparedStatement2.setString(17, cosigner_national_id);
        preparedStatement2.executeUpdate();

某些日期不是必需的，并且在某些情况下适用，因此用户在这种情况下无法选择日期。

Answer 1

检查每个 JXDatePicker 的日期，例如 jXDatePicker2.getDate() 是否为 null。如果该日期恰好为空，则不要调用 format.format。如果日期为空并且按下 Enter 键，我会收到与 format.format 行中提到的完全相同的错误。相反，选择一些默认时间，例如 new Date(0); 含义:

format.format(new Date(0));