Why did I get this error : java.lang.Exception: XM

问题:

My Java program look like this :

  public class Biz_Manager
  {
    static Contact_Info_Setting Customer_Contact_Info_Panel;
    static XMLEncoder XML_Encoder;
    ......

    void Get_Customer_Agent_Shipping_Company_And_Shipping_Agent_Net_Worth_Info()
    {
      try
      {
        XML_Encoder=new XMLEncoder(new BufferedOutputStream(new FileOutputStream(Customer_Contact_Info_Panel.Contact_Info_File_Path)));
        XML_Encoder.writeObject(Customer_Contact_Info_Panel.Contacts_Vector);
      }
      catch (Exception e) { e.printStackTrace(); }
      finally
      {
        if (XML_Encoder!=null)
        {
          XML_Encoder.close();   // <== Error here , line : 9459
          XML_Encoder=null;
        }
      }
    }
  }

// =======================================================================

public class Contact_Info_Setting extends JPanel implements ActionListener,KeyListener,ItemListener
{
  public static final long serialVersionUID=26362862L;
  ......
  Vector<Contact_Info_Entry> Contacts_Vector=new Vector<Contact_Info_Entry>();
  ......
}

// =======================================================================

package Utility;

import java.io.*;
import java.util.*;
import javax.jdo.annotations.IdGeneratorStrategy;
import javax.jdo.annotations.IdentityType;
import javax.jdo.annotations.PersistenceCapable;
import javax.jdo.annotations.Persistent;
import javax.jdo.annotations.PrimaryKey;

@PersistenceCapable(identityType=IdentityType.APPLICATION)
public class Contact_Info_Entry implements Serializable
{
  @PrimaryKey
  @Persistent(valueStrategy=IdGeneratorStrategy.IDENTITY)
  public Long Id;
  public static final long serialVersionUID=26362862L;
  public String Contact_Id="",First_Name="",Last_Name="",Company_Name="",Branch_Name="",Address_1="",Address_2="",City="",State="",Zip="",Country="";
  ......
  public boolean B_1;
  public Vector<String> A_Vector=new Vector<String>();

  public Contact_Info_Entry() { }
  public Contact_Info_Entry(String Other_Id) { this.Other_Id=Other_Id; }
  ......
  public void setId(Long value) { Id=value; }
  public Long getId() { return Id; }

  public void setContact_Id(String value) { Contact_Id=value; }
  public String getContact_Id() { return Contact_Id; }

  public void setFirst_Name(String value) { First_Name=value; }
  public String getFirst_Name() { return First_Name; }

  public void setLast_Name(String value) { Last_Name=value; }
  public String getLast_Name() { return Last_Name; }

  public void setCompany_Name(String value) { Company_Name=value; }
  public String getCompany_Name() { return Company_Name; }
  ......
}

I got this error message :

java.lang.Exception: XMLEncoder: discarding statement Vector.add(Contact_Info_Entry); Continuing ... java.lang.Exception: XMLEncoder: discarding statement Vector.add(Contact_Info_Entry); Continuing ... java.lang.Exception: XMLEncoder: discarding statement Vector.add(Contact_Info_Entry); Continuing ... java.lang.Exception: XMLEncoder: discarding statement Vector.add(Contact_Info_Entry); Continuing ... Exception in thread "Thread-8" java.lang.NullPointerException at java.beans.XMLEncoder.outputStatement(XMLEncoder.java:611) at java.beans.XMLEncoder.outputValue(XMLEncoder.java:552) at java.beans.XMLEncoder.outputStatement(XMLEncoder.java:682) at java.beans.XMLEncoder.outputStatement(XMLEncoder.java:687) at java.beans.XMLEncoder.outputValue(XMLEncoder.java:552) at java.beans.XMLEncoder.flush(XMLEncoder.java:398) at java.beans.XMLEncoder.close(XMLEncoder.java:429) at Biz_Manager.Get_Customer_Agent_Shipping_Company_And_Shipping_Agent_Net_Worth_Info(Biz_Manager.java:9459)

Seems it can't deal with vector, why ? Anything wrong ? How to fix it ?

Frank

回答1:

Maybe the answer is there : http://bugs.sun.com/bugdatabase/view_bug.do;jsessionid=36649bcae69963754fe1bd095030?bug_id=4671142

回答2:

for me this meant "you need a no arg constructor" (different class, obviously)