#180 Saving a new Object essentially create new referance objects

[Buddhika Ariyaratne]

Dear Sir,

I am very impressed about your object database. It is excellent. I have a small problem. I will be grateful to you if you can solve that.

When I save an object, which contain a reference to a previously saved (and retrieved) object, it also saves the referred object as a new one.

I have a Country class with String country attribute. I also have a City class with String City attribute and Country country attribute. First I saved a Country Object. Then I retrieve the saved object with odb.getObjects and assign it as the country in a new City object. When I save the city object, it create a new country object. That is not the expected behavior. I have copied the codes here and the full net beans project with out your library.

I will be grateful to you if you can help me in this regard.

Thanks

Buddhika

********************* Country Class ******************

package cities;

public class Country {
String country;

public Country(String country) {
this.country = country;
}

public String getCountry() {
return country;
}

@Override
public String toString() {
return country;
}

public void setCountry(String country) {
this.country = country;
}

}

******************** City CLass **************************

package cities;

public class City {
String city;
Country country;

public City(String city, Country country) {
this.city = city;
this.country = country;
}

@Override
public String toString() {
return city ;
}

public Country getCountry() {
return country;
}

public void setCountry(Country country) {
this.country = country;
}

public City(String city) {
this.city = city;
}

public String getCity() {
return city;
}

public void setCity(String city) {
this.city = city;
}

}

******************** Manager Class ***********************

package cities;

import javax.swing.JList;
import org.neodatis.odb.ODB;
import org.neodatis.odb.ODBFactory;
import org.neodatis.odb.Objects;

public class Manager {
static String odbDB = "city.odb";

public static void fillList(Class fillClass, JList jList){
ODB odb = ODBFactory.open(odbDB);
Objects<Object> dbObjects = odb.getObjects(fillClass);
odb.close();

Object[] objects = dbObjects.toArray();
jList.removeAll();
jList.setListData(objects);

}

public static void saveObject(Object object){
ODB odb = ODBFactory.open(odbDB);
odb.store(object);
odb.close();
}

}

******************* frmCity class ********************

package cities;

import com.sun.org.apache.bcel.internal.generic.LSTORE;
import org.neodatis.odb.ODB;
import org.neodatis.odb.ODBFactory;
import org.neodatis.odb.Objects;
import org.neodatis.odb.core.query.IQuery;
import org.neodatis.odb.impl.core.query.criteria.CriteriaQuery;

public class frmCity extends javax.swing.JFrame {

public frmCity() {
initComponents();
}

public static void fillList(){
ODB odb = ODBFactory.open("city.odb");
Objects<Object> objects = odb.getObjects(Country.class);

}

@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {

jLabel1 = new javax.swing.JLabel();
txtCity = new javax.swing.JTextField();
jScrollPane1 = new javax.swing.JScrollPane();
lstCountry = new javax.swing.JList();
Country = new javax.swing.JLabel();
btnAddCity = new javax.swing.JButton();
jLabel2 = new javax.swing.JLabel();
txtCountry = new javax.swing.JTextField();
btnAddCountry = new javax.swing.JButton();

setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
addWindowListener(new java.awt.event.WindowAdapter() {
public void windowOpened(java.awt.event.WindowEvent evt) {
formWindowOpened(evt);
}
});

jLabel1.setText("City");

lstCountry.setModel(new javax.swing.AbstractListModel() {
String[] strings = { "Item 1", "Item 2", "Item 3", "Item 4", "Item 5" };
public int getSize() { return strings.length; }
public Object getElementAt(int i) { return strings[i]; }
});
jScrollPane1.setViewportView(lstCountry);

Country.setText("jLabel2");

btnAddCity.setText("Add City");
btnAddCity.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnAddCityActionPerformed(evt);
}
});

jLabel2.setText("Country");

btnAddCountry.setText("Add Country");
btnAddCountry.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnAddCountryActionPerformed(evt);
}
});

javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(btnAddCountry)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 56, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(Country)
.addComponent(jLabel2))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(txtCountry, javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jScrollPane1)
.addComponent(txtCity, javax.swing.GroupLayout.DEFAULT_SIZE, 242, Short.MAX_VALUE)))
.addComponent(btnAddCity, javax.swing.GroupLayout.PREFERRED_SIZE, 92, javax.swing.GroupLayout.PREFERRED_SIZE))
.addContainerGap(32, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(27, 27, 27)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel1)
.addComponent(txtCity, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(Country))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnAddCity)
.addGap(43, 43, 43)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(txtCountry, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel2))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnAddCountry)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);

pack();
}// </editor-fold>

private void btnAddCountryActionPerformed(java.awt.event.ActionEvent evt) {
Country country = new Country(txtCountry.getText());
Manager.saveObject(country);
Manager.fillList(Country.class, lstCountry);
}

private void btnAddCityActionPerformed(java.awt.event.ActionEvent evt) {
City city = new City(txtCity.getText());
city.setCountry((Country) lstCountry.getSelectedValue());
Manager.saveObject(city);
Manager.fillList(Country.class, lstCountry);
}

private void formWindowOpened(java.awt.event.WindowEvent evt) {
Manager.fillList(Country.class, lstCountry);
}

public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new frmCity().setVisible(true);
}
});
}

// Variables declaration - do not modify
private javax.swing.JLabel Country;
private javax.swing.JButton btnAddCity;
private javax.swing.JButton btnAddCountry;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JList lstCountry;
private javax.swing.JTextField txtCity;
private javax.swing.JTextField txtCountry;
// End of variables declaration

}

******************************************* Main Class ********************

package cities;

public class Main {

public static void main(String[] args) {
frmCity city = new frmCity();
city.setVisible(true);
}

}

[Buddhika Ariyaratne]

Netbeans Project with out library

[Nobody/Anonymous]

CdhCKE I am so grateful for your post.Really thank you! Cool.

[Olivier]

Hi Buddhika,

If references are not loaded, NeoDatis will consider they are new objects. So you need to load the references before 'updating them'.

Thanks,
Olivier