java - StandardWrapperValve[jsp] : Servlet. servlet jsp 的 service() 抛出异常 java.lang.IllegalArgumentException:无法将给定对象格式化为日期

Question

我的 java jsp servlet 代码中出现异常，我收到标题中提到的错误。
我尝试了下面提到的 stackoverflow 链接中的解决方案，但没有用。

我的问题是mysql数据库中输入了空值。我已经被困在其中两天了。

Java : Cannot format given Object as a Date

 import java.sql.Timestamp;    
 import java.text.ParseException;    
 import java.text.SimpleDateFormat;   
 import java.time.Instant;   
 import java.util.Date;   
 import java.util.logging.Level;   
 import java.util.logging.Logger;

 public class SetDate  
 {  
 public static java.util.Date set(String s,String f)    
 {   
 java.text.SimpleDateFormat sdf=new java.text.SimpleDateFormat(f);    
 java.util.Date date=null;   
 try  
 {    
 date=sdf.parse(s);    
 }     
 catch (ParseException ex)  
 {    
 Logger.getLogger(SetDate.class.getName()).log(Level.SEVERE, null, ex);   
 }      
 return date;     
 }    


public static String format(Object time,String f) throws ParseException   
{      
    SimpleDateFormat sdf=new SimpleDateFormat(f);       
    System.out.println("Date:- " +sdf.format(time));        
    return sdf.format(time);        
}   
}

错误日志:

Warning:   StandardWrapperValve[jsp]: Servlet.service() for servlet jsp   threw exception
java.lang.IllegalArgumentException: Cannot format given Object as a Date      
at java.text.DateFormat.format(DateFormat.java:310)       
at java.text.Format.format(Format.java:157)       
at myweb.tool.SetDate.format(SetDate.java:35)        

Answer 1

更改:

public static String format(Object time,String f) throws ParseException   
{      
    SimpleDateFormat sdf=new SimpleDateFormat(f);       
    System.out.println("Date:- " +sdf.format(time));        
    return sdf.format(time);        
}   

至:

public static String format(Object time,String f) throws ParseException   
{   
    if (time == null) 
        rteurn null;

    SimpleDateFormat sdf=new SimpleDateFormat(f);       
    System.out.println("Date:- " +sdf.format(time));        
    return sdf.format(time);        
}