Hibernate: OutOfMemory Error!

[George Ren]

Hi!everyone,
I use Hibernate + JBX to wirte a piece of code.Here is my code:

 
/*
 * OperateDB.java 2004-8-16
 * Copyright (c) 2004 Rsqr Studio. All Rights Reserved.
 * Porgrammed by George Ren
 */
 
package database;
 

import net.sf.hibernate.Session;
import net.sf.hibernate.Transaction;
import net.sf.hibernate.SessionFactory;
import net.sf.hibernate.cfg.Configuration;
import net.sf.hibernate.tool.hbm2ddl.SchemaExport;
import net.sf.hibernate.*;
import java.util.*;
import java.io.*;
 
/**
 * This class handle the operation of database, contains query
 * insert, delete and search.
 * <p>Title:</p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2004</p>
 * <p>Company: Rsqr Studio</p>
 * @author George Ren
 * @version 1.0.2
 */
public class OperateDB {
  java.util.List list;
  Session s;
  Query q;
  private static SessionFactory sessionFactory;
  Transaction tx = null;
  StringBuffer strBuff = new StringBuffer();
  String str[] = new String[7];
 

  /**
   * The constructor
   */
  public OperateDB() {
  }
 
  /**
   * Update the table named data in the database.
   *
   * @param message String
   */
  public void updateData(String message){
    for (int i = 0; i < message.length(); i++) {
      int j = 0;
      do{
        strBuff.append(message.charAt(i));
      }while (! (message.charAt(i) == '+'));
      System.out.println(strBuff.length());
      str[j] = strBuff.toString();
      j++;
    }
    try {
      Configuration conf = new Configuration().addClass(Data.class);
      sessionFactory = conf.buildSessionFactory();
      s = sessionFactory.openSession();
      list = s.find("from UserInfo as ui where ui.moduleNo = ?", str[0],
                    Hibernate.STRING);
      s.flush();
 
      if (list.isEmpty() == true) {        //if record do not exists, insert it.
        tx = s.beginTransaction();
        Data data = new Data();
        data.setModuleNo(str[0]);
        data.setV(str[1]);
        data.setA(str[2]);
        data.setW(str[3]);
        data.setVar(str[4]);
        data.setFactor(str[5]);
        data.setKw(str[6]);
        s.save(data);
        tx.commit();
      }
      else {         //if record already exists, update it.
        tx = s.beginTransaction();
        Data data = new Data();
        data = (Data)list.get(0);
        data.setV(str[1]);
        data.setA(str[2]);
        data.setW(str[3]);
        data.setVar(str[4]);
        data.setFactor(str[5]);
        data.setKw(str[6]);
        s.save(data);
        tx.commit();
      }
      s.close();
    }
    catch (Exception ex) {
      System.out.println("operate table data failed...");
      ex.printStackTrace();
    }
  }
 
  public static void main(String args[]){
    OperateDB operateDB = new OperateDB();
    operateDB.updateData("002+1.0000+1.0000+0.8000+0.6000+1.0000");
  }
}
 
 

But when running, it is also a OutOfMemory Error. What's your opinion?

Thanks for help!


Regard,

George

[pascal betz]

hi

the reason for OutOfMemory is not Hibernate ! its your strange way of splitting the input string...once you enter the do-while loop the index i is never incremented so you are looking at the same character over and over... you will create an huge StringBuffer ...

- for splitting the Input String: Check out StringTokenizer or String.split() method added in 1.4

- why is there UserInfo and Data class ? you retrieve UserInfo Objects from your query ?


- Make sure always to close your Session/end Transaction (also in the case of an Exception). use try/catch/finally !

you can find more on this here:
http://www.hibernate.org/hib_docs/reference/en/html/manipulatingdata.html#manipulatingdata-endingsession-exceptions


- your OperateDB class is not Thread Safe (e.g. Transaction is a member variable)

- You should not create the SessionFactory every time the updateData method is called (SessionFactory is an expensive Object to create). Create it once and then just retrieve Session Objects from your SessionFactory every call to updateData

- have a look at saveOrUpdate() method in Session

- if you just want to retrieve one result (if you have the ID) you can use something like that

 
SomeClass something  = (SomeClass)sess.get(SomeClass.class, anId);

here is the API:
API

cheers

pascal
[ August 20, 2004: Message edited by: pascal betz ]

[George Ren]

Pascal,thank you very much for such a fantastic help! I think I have figured out that problem.

Wish you a nice day!