解析异常 Java

Question

我正在编写一个约会程序，允许用户输入约会日期、描述和约会类型。一切正常，直到他们选择打印一系列日期的“打印范围”，当他们选择这样做时，它会告诉他们输入开始日期和结束日期，然后程序会从这些日期之间提取所有约会并将它们显示到输出框中。

这是我在打印范围时遇到的错误：

AppointmentNew.java:68: unreported exception java.text.ParseException; must be caught or declared to be thrown
        Date lowDate = sdf.parse(stdin.nextLine());
                                ^
AppointmentNew.java:70: unreported exception java.text.ParseException; must be caught or declared to be thrown
        Date highDate = sdf.parse(stdin.nextLine());  
                                 ^
AppointmentNew.java:77: unreported exception java.text.ParseException; must be caught or declared to be thrown
           Date newCurrentDate = sdf.parse(currentDate); 

我想我可能应该做一个 try/catch 块，但我不确定如何做，并且想知道是否有人可以为我提供答案或示例来修复这些错误。

这是我认为发生解析错误的一些代码：

import java.util.*;
import java.text.SimpleDateFormat;
import java.util.Date;

public class AppointmentNew 
{
public static void main (String[] args) throws Exception
{

if (choiceNum == 2)
     {
        System.out.print("\n\n\tEnter START Date in mm/dd/yyyy format: ");
        SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy");
        Date lowDate = sdf.parse(stdin.nextLine());
        System.out.print("\n\n\tEnter END Date in mm/dd/yyyy format: ");
       Date highDate = sdf.parse(stdin.nextLine());  

        for(int i = 0; i < list.size(); i++)
        {
           int dateSpot = list.get(i).indexOf(" ");
           String currentDate = list.get(i);
           currentDate.substring(0, dateSpot);
           Date newCurrentDate = sdf.parse(currentDate); 

           if (newCurrentDate.compareTo(lowDate) >= 0 && newCurrentDate.compareTo(highDate) <= 0)
           {
              System.out.println("\n\t" + list.get(i));

           }
        }
     }

Answer 1

Parse Exception 是检查异常，所以你必须处理它。 通过 throws 或 try catch 块。

public static void main (String[] args)

应该是

public static void main (String[] args) throws ParseException

或者在try catch块中

try {
    //All your parse Operations
} catch (ParseException e) {
   //Handle exception here, most of the time you will just log it.
   e.printStackTrace();
  }

Answer 2

为什么会出现错误：

如何解决：

用try catch 包围有问题的代码 - 这就像在说，我将捕获错误，记录它并希望能够对此采取一些措施。

 try {  // add this line
             System.out.print("\n\n\tEnter START Date in mm/dd/yyyy format: ");
             SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy");
             Date lowDate = sdf.parse(stdin.nextLine());
             System.out.print("\n\n\tEnter END Date in mm/dd/yyyy format: ");  
             Date highDate = sdf.parse(stdin.nextLine());  

             for(int i = 0; i < list.size(); i++)
             {
                int dateSpot = list.get(i).indexOf(" ");
                String currentDate = list.get(i);
                currentDate.substring(0, dateSpot);
                Date newCurrentDate = sdf.parse(currentDate); 

                if (newCurrentDate.compareTo(lowDate) >= 0 && newCurrentDate.compareTo(highDate) <= 0)
                {
                   System.out.println("\n\t" + list.get(i));   
                }
             }
         } catch (ParseException ex) {
              ex.printStackTrace(); // or log it using a logging framework
         }

或者把它扔到 main - 在这里，就像在说：不管是谁在调用这个方法，如果它发生，请处理这个问题：

public static void main (String[] args) throws Exception