字符串到java.sql.Date [英] String to java.sql.Date
问题描述
我知道这个问题已经被问了很多。我确实看过。我花了几个小时环顾四周，并试图找出答案。我应该编写一个程序，该程序在数据库中存储相当于约会列表的内容，包括描述，日期，开始时间和结束时间。它必须接受用户的输入才能添加或取消约会，据我所知，这意味着我需要将字符串转换为日期。
I realize this has been asked a lot. I did actually look. I've spent hours looking around and trying to figure this out. I'm supposed to be making a program that stores what amounts to a list of appointments in a database, with a description, date, start time, and end time. It has to take input from the user to add or cancel appointments, so as far as I know that means I need to convert a string to a date.
这些是我的导入：
import java.io.File;
import java.io.IOException;
import java.sql.Connection;
import java.sql.Date;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Time;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Scanner;
These are my imports: import java.io.File; import java.io.IOException; import java.sql.Connection; import java.sql.Date; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.sql.Time; import java.text.DateFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Scanner;
如您所见，那里没有java.util.Date。这是我遇到错误的地方：
As you can see, no java.util.Date there. Here is the bit where I'm getting the error:
private static java.sql.Date getDay()
{
Scanner in = new Scanner(System.in);
String input;
Date apptDay = null;
DateFormat df = new SimpleDateFormat("yyyy/MM/dd");
java.sql.Date sqlDate;
System.out.println("\nPlease enter the date of the appointment, format: yyyy/mm/dd");
while(apptDay == null)
{
try
{
input = in.next();
apptDay = (Date) df.parse(input);
}
catch(ParseException e)
{
System.out.println("Please enter a valid date! Format is yyyy/mm/dd");
}
}
sqlDate = new Date(apptDay.getTime());
return sqlDate;
}
我在其中添加了java.sql.Dates并对其进行了修改一堆试图使其工作，但它仍然给我这个：
I've added java.sql.Dates to it and mucked about with it a bunch trying to get it to work, but it's still giving me this:
线程 main中的异常java.lang.ClassCastException：java无法将Calendar.getDay（Calendar.java:47）上的.util.Date强制转换为java.sql.Date
任何关于我做错了什么或如何做这项工作的想法都将不胜感激。
Any ideas on what I'm doing wrong or how to make this work would be very much appreciated.
编辑：我想，如果我再添加一点调用此代码的代码，这样也许可以更清楚地说明我是如何使用它的，所以这里是addAppointment（）方法，因此您可以看到getDay（）的调用位置以及调用的方向。
I thought perhaps it would help if I added the bit of code that is calling this so maybe it will be more clear how I am trying to use it, so here is the addAppointment() method, so you can see where getDay() is being called and where it's going.
public static void addAppointment() throws SQLException
{
//get the info
String desc = getDesc();
java.sql.Date apptDay = getDay();
Time[] times = getTime();
Time startTime = times[0];
Time endTime = times[1];
int key;
Connection conn = SimpleDataSource.getConnection(); //connect to the database
try
{
PreparedStatement max = conn.prepareStatement("SELECT MAX(ID) FROM Calendar");
ResultSet result = max.executeQuery();
key = result.getInt("ID") + 1;
PreparedStatement stat = conn.prepareStatement(
"INSERT INTO Calendar " +
"VALUES (?, ?, ?, ?, ?)");
stat.setInt(1, key);
stat.setString(2, desc);
stat.setDate(3, apptDay);
stat.setTime(4, startTime);
stat.setTime(5, endTime);
stat.execute();
System.out.println("\nAppointment added!\n");
}
finally
{
conn.close(); //finished with the database
}
}
推荐答案
将输入格式更改为 yyyy-MM-dd 并使用 java.sql.Date.valueOf（字符串日期）方法，该方法将上述格式的字符串直接转换为java.sql.Date值。
It would be much simpler to change the input format to yyyy-MM-dd and use java.sql.Date.valueOf(String date) method which converts a string in the above format to a java.sql.Date value directly.
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