I cannot remove values of data type properties in Jena

I'm trying to remove values of datatype properties of an instance through an interface which I created in java but it does not work. It gives me an

Exception in thread "AWT-EventQueue-0" java.util.ConcurrentModificationException.

I don't understand why. Can you please explain me what's wrong?

Here is my code for button remove:

//Button Remove
public class ActionRemove implements ActionListener
{

    public void actionPerformed(ActionEvent evt)
    {

        StmtIterator iter = onto.model.listStatements();

        while (iter.hasNext()) 
        {
            Statement stmt  = iter.nextStatement(); 

            Resource  subject = stmt.getSubject(); 
            Property  predicate = stmt.getPredicate();  
            RDFNode object  = stmt.getObject();  
            if(subject.toString().equals (onto.uriBase+"#"+tabTF[0].getText()))
            {

                onto.model.remove(stmt);

            }

    }
}
}

My complete code:

import java.util.*;
import com.hp.hpl.jena.rdf.model.*;
import com.hp.hpl.jena.ontology.*;
import com.hp.hpl.jena.ontology.impl.*;
import com.hp.hpl.jena.util.*;
import java.io.*;
import java.awt.*;  
import java.awt.event.*; 
import com.hp.hpl.jena.vocabulary.RDF;
import com.hp.hpl.jena.vocabulary.XSD;
import com.hp.hpl.jena.util.iterator.ExtendedIterator;




public class FamilyModel extends Frame
{   
TextField[]tabTF=new TextField[4];
Button bAjout, bModifier, bSupprimer, bPrecedent, bSuivant, bRemove; //buttons Add, Remove, Previous, Next
OntModel model;
Onto onto;
int indice=0;
int p=0;
Resource p1; 


Button creerBouton(String S, int x, int y)
{
    Button b=new Button(S);
    add(b);         
    b.setBounds(x,y,120,30);
    return b;
}

void creerLabel(String etiquette, int x, int y)
{
    Label la=new Label(etiquette);
    la.setBounds(x,y,100,25);
    add(l开发者_C百科a);
}


public FamilyModel ()
{
        setLayout (null);
        setBackground (Color.pink);
        setBounds (100,200,900,450);
        addWindowListener(new FermerFenetre());

        creerLabel("Prenom : ",10,50);
        creerLabel("Nom : ",10,100);
        creerLabel("Date de Naissance: ",10,145);
        creerLabel("Genre (H ou F): ",10,190);

        //TextFields
        for(int i=0;i<4;i++)
        {
            tabTF[i]=new TextField("");
            tabTF[i].setBackground(Color.white);
            add(tabTF[i]);
        }
        tabTF[0].setBounds(120,45,150,25);
        tabTF[1].setBounds(120,100,150,25);
        tabTF[2].setBounds(120,145, 100,25);
        tabTF[3].setBounds(120,190, 45,25);

        bAjout=creerBouton("Ajouter",20,250); 
        setVisible(true);

        bModifier=creerBouton("Modifier",138,250); 
        setVisible(true);

        bSupprimer=creerBouton("Supprimer",250,250); 
        setVisible(true);

        bPrecedent=creerBouton("Precedent",360,250); 

        bSuivant=creerBouton("Suivant",450,250); 

        bRemove=creerBouton("Supprimer",600,250);

        setVisible(true);   

        onto = new Onto();

         readRDFfile();

        traitement(this);   

}



void traitement(Frame fenetre)
{

    bAjout.addActionListener(new ActionAjoutPersonne());
    bModifier.addActionListener(new ActionRemove());
    bSuivant.addActionListener(new ActionSuivant());
    bPrecedent.addActionListener(new ActionPrecedent());
    bRemove.addActionListener(new ActionRemove());

}


//Button Add
public class ActionAjoutPersonne implements ActionListener
{

    public void actionPerformed(ActionEvent evt)
    {


        p1=onto.model.createResource(onto.uriBase+"#"+tabTF[0].getText()); 
        p1.addProperty(onto.aPourPrenom, tabTF[0].getText());         
        p1.addProperty(onto.aPourNom, tabTF[1].getText());         
        p1.addProperty(onto.aDateNaiss, tabTF[2].getText()); 

        if (tabTF[3].getText().equals("F"))
        {
            p1.addProperty(onto.aGenre, tabTF[3].getText()); 
            p1.addProperty(RDF.type, onto.femme);

        }
        else if (tabTF[3].getText().equals("H"))
        {
            p1.addProperty(onto.aGenre, tabTF[3].getText());    
            p1.addProperty(RDF.type, onto.homme);
        }

        StringWriter sw = new StringWriter();
        onto.model.write(sw, "RDF/XML-ABBREV");
        String owlCode = sw.toString();
        File file = new File("d:/Onto.rdf");
        try{
            FileWriter fw = new FileWriter(file);
            fw.write(owlCode);
            fw.close();
        } catch(FileNotFoundException fnfe){
            fnfe.printStackTrace();} 
        catch(IOException ioe){
                ioe.printStackTrace();
        }  

    }
}



//Button Remove
public class ActionRemove implements ActionListener
{

    public void actionPerformed(ActionEvent evt)
    {

        StmtIterator iter = onto.model.listStatements();

        while (iter.hasNext()) 
        {
            Statement stmt  = iter.nextStatement(); 

            Resource  subject = stmt.getSubject(); 
            Property  predicate = stmt.getPredicate();  
            RDFNode object  = stmt.getObject();  
            if(subject.toString().equals (onto.uriBase+"#"+tabTF[0].getText()))
            {

                onto.model.remove(stmt);

            }

    }
  }
}


//Read Onto.rdf
public void readRDFfile()
{
     String inputFile="D:/Onto.rdf";
     try
     {
     InputStream in =new  FileInputStream(inputFile);
      if (in == null) {  
      System.out.println("File not found");
     }  
      onto.model.read(in," ");

     }catch(Exception e) {
           System.out.println("model.read catched error: " + e);
     }
}

//Button Next
class ActionSuivant implements ActionListener
{
    public void actionPerformed(ActionEvent evt)
    {

        ++indice;
        ExtendedIterator instances = onto.personne.listInstances();
        Individual instance = null;
        Individual firstInstance = null;
        for (p = 0; p < indice && instances.hasNext(); p++) {
            instance = (Individual) instances.next();
            if (firstInstance == null) {
                firstInstance = instance;
            }
        }    
        if (p < indice) {
            indice = 1;
            instance = firstInstance;
        }
        tabTF[0].setText(instance.getPropertyValue(onto.aPourPrenom).toString());
        tabTF[1].setText(instance.getPropertyValue(onto.aPourNom).toString());
        tabTF[2].setText(instance.getPropertyValue(onto.aDateNaiss).toString());
        tabTF[3].setText(instance.getPropertyValue(onto.aGenre).toString());
    }

} 

//Button Previous
class ActionPrecedent implements ActionListener
{
    public void actionPerformed(ActionEvent evt)
    {      
      --indice; 
      //Instances de la Classe Personne          
        ExtendedIterator instances=onto.personne.listInstances();

        Individual instance = null;
                for(p = 0; p < indice && instances.hasNext(); p++)
                {
                   instance = (Individual) instances.next();

                }   
                 tabTF[0].setText(instance.getPropertyValue(onto.aPourPrenom).toString());
                 tabTF[1].setText(instance.getPropertyValue(onto.aPourNom).toString());
                 tabTF[2].setText(instance.getPropertyValue(onto.aDateNaiss).toString());
                 tabTF[3].setText(instance.getPropertyValue(onto.aGenre).toString());

          }
} 


//Close window when X is pressed   
public class FermerFenetre extends WindowAdapter 
{

    public void windowClosing(WindowEvent evt)
    {
        if(evt.getWindow().getName().equals("frame0"))
        {
            System.exit(0);
        }
        else
        {
            evt.getWindow().dispose();
        }
    }
}


//Ontology
public class Onto 
{
    OntClass personne, genre, homme, femme, feminin, masculin, evenement, deces, mariage, divorce;
    OntModel model;
    String uriBase;
    ObjectProperty aPourFils, aPourFille, aGenre;
    DatatypeProperty aPourNom, aPourPrenom, aDateNaiss;

    public Onto (){
    model = ModelFactory.createOntologyModel( OntModelSpec.OWL_MEM_MICRO_RULE_INF );
    uriBase = "http://www.something.com/FAM";
    model.createOntology(uriBase);

    //Classes
    personne = model.createClass(uriBase+"personne");
    femme = model.createClass(uriBase+"femme");
    homme = model.createClass(uriBase+"homme");
    genre = model.createClass(uriBase+"genre");
    feminin = model.createClass(uriBase+"feminin");
    masculin = model.createClass(uriBase+"masculin");
    evenement = model.createClass(uriBase+"evenement");
    deces = model.createClass(uriBase+"deces");
    mariage = model.createClass(uriBase+"mariage");
    divorce = model.createClass(uriBase+"divorce");


    //Sub-classes
    genre.addSubClass(feminin);
    genre.addSubClass(masculin);
    personne.addSubClass(homme);
    personne.addSubClass(femme);
    evenement.addSubClass(deces);
    evenement.addSubClass(mariage);
    evenement.addSubClass(divorce);

    aPourFils = model.createObjectProperty(uriBase+"aPourFils");
    aPourFils.setDomain(personne);
    aPourFils.setRange(homme);

    aPourFille = model.createObjectProperty(uriBase+"aPourFille");
    aPourFille.setDomain(personne);
    aPourFille.setRange(femme);

    aGenre = model.createObjectProperty(uriBase+"aGenre");
    aGenre.setDomain(personne);
    aGenre.setRange(genre);

    aPourNom = model.createDatatypeProperty(uriBase+"aPourNom"); 
    aPourNom.setDomain(personne);
    aPourNom.setRange(XSD.xstring);

    aPourPrenom = model.createDatatypeProperty(uriBase+"aPourPrenom"); 
    aPourPrenom.setDomain(personne);
    aPourPrenom.setRange(XSD.xstring);

    aDateNaiss = model.createDatatypeProperty(uriBase+"aDateNaiss"); 
    aDateNaiss.setDomain(personne);
    aDateNaiss.setRange(XSD.xstring);
    }

}

public static void main(String args[]) 
{

    new FamilyModel();      
}
}

You have removed an item from a collection and then continued to use a previous iterator on it.

Most of the java collection iterators have the "fail fast" property. Once they detect that the underlying collection has changed they will throw a ConcurrentModificationException.

Your solution is to do a two step removal process:

1. iterate and find the nodes that you need to remove
2. iterate the list of nodes you want removed (found in first step) and actually remove them from the original collection.

Code (assuming Java 5):

//Button Remove
public class ActionRemove implements ActionListener
{

    public void actionPerformed(ActionEvent evt)
    {
        List<Statement> statementsToRemove = new ArrayList<Statement>();

        // step 1
        StmtIterator iter = onto.model.listStatements();
        while (iter.hasNext()) 
        {
            Statement stmt  = iter.nextStatement(); 

            Resource  subject = stmt.getSubject(); 
            Property  predicate = stmt.getPredicate();  
            RDFNode object  = stmt.getObject();  
            if(subject.toString().equals (onto.uriBase+"#"+tabTF[0].getText()))
            {
                statementsToRemove.add(stmt);
            }
       }

       // step 2
       for( Statement stmt : statementsToRemove) 
       {
            onto.model.remove(stmt);
       }
   }
}

There is another way (see http://download.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/CopyOnWriteArrayList.html class) but since your collection is inside the Jena api you can't use it ;).