NullPointerException when querying in Hibernate + JBX

georgeren · **Joined:** Sun Aug 08, 2004 2:38 am **Posts:** 9

Hibernate version:2.1.3

Mapping documents:

Code between sessionFactory.openSession() and session.close():

Full stack trace of any exception that occurs:

Name and version of the database you are using:MySQL

Debug level Hibernate log excerpt:

Hi,everyone!
I use JBX + Hibernate to write a query method, and show the result in a JTable. Here is my code:

Code:

String rowData[][] = new String[255][5];
UserInfo users[] = null;

public void query(){
    try {
      Configuration conf = new Configuration().addClass(UserInfo.class);
      sessionFactory = conf.buildSessionFactory();
      s = sessionFactory.openSession();
      Transaction t = s.beginTransaction();
    }
    catch (MappingException ex) {
      ex.printStackTrace();
    }
    catch (HibernateException ex) {
      ex.printStackTrace();
    }
    if (tfName.getText() == "all"){
      try {
        tx = s.beginTransaction();
        list = s.find("from UserInfo as ui");
        tx.commit();
        s.flush();
        s.close();
      }
      catch (HibernateException ex1) {
        System.out.println("excute sql1 query failed.");
        ex1.printStackTrace();
      }
    }else{
      try {
       list = s.find("from UserInfo as ui where ui.name = ?" , tfName.getText() , Hibernate.STRING);
       s.flush();
       s.close();
      }
      catch (HibernateException ex2) {
        System.out.println("excute sql2 query failed.");
        ex2.printStackTrace();
      }
    }
    for(int i=0 ; i<list.size() ; i++){
      try{
        if(list == null){
          System.out.println("list equals NULL!");
        }
        System.out.println(list.size());
        System.out.println(i);
        users[i] = (UserInfo)list.get(i);
      }catch(java.lang.NullPointerException ex){
        System.out.println("equals null!");
      }
      rowData[i][0] = users[i].getId();
      rowData[i][1] = users[i].getName();
      rowData[i][2] = users[i].getModuleNo();
      rowData[i][3] = users[i].getMobileNo();
      rowData[i][4] = users[i].getAccount();
    }
    JTable jTable1 = new JTable(rowData,columnName);
    jTable1.setBounds(new Rectangle(14, 109, 338, 109));
    jTable1.setEnabled(false);
    jTable1.setFont(new java.awt.Font("Dialog", 0, 12));
    panel1.add(jTable1, null);
  }

But when running, it always be a NullpointerException. I know I havn't initalize the rowData[][] and users[], but I don't know how to make in works.

Any ideas?

tq · **Posted:** Thu Aug 12, 2004 3:00 am

you call list.size() before checking if null, so the null check in that try block is pointless.
anyhat you now need to figure out why you get a null list back, I guess that's why you're posting, but to help anymore it would be useful to have the info mentioned in the red box.

steve · **Posted:** Thu Aug 12, 2004 6:10 am

I don't see where you ever initialize the users array to anything other than null...

georgeren · **Joined:** Sun Aug 08, 2004 2:38 am **Posts:** 9

I've tested that the list is not null, the query return two class entities. So I think list.size() won't be a null, I know maybe it is due to the initialization of the arrays. But I don't know how to initialize them as I don't know the size. Please help~~~

Thanks a lot!

Regards,

steve · **Posted:** Fri Aug 13, 2004 1:21 pm

something like:

Code:

    users = new UserInfo[list.size()];
    for(int i=0 ; i<list.size() ; i++){ 
      try{ 
        ...

Although, honestly, I'm mystified as to the entire purpose of this users array.

georgeren · **Joined:** Sun Aug 08, 2004 2:38 am **Posts:** 9

Thanks, steve:) Now I know how to deal with it~~~!

Have a nice day!