Error: Class cannot be read from Sqlite3 database. about sugar HOT 10 CLOSED

private static Context context;
private String nom;
private String phoneNo;
Groupe groupe;
boolean selected = false;

public Contact(Context context){
    super(context);
}

public Contact(String nom, String phoneNo, boolean selected) {
  super(context);
  this.nom = nom;
  this.phoneNo = phoneNo;
  this.selected = selected;
 }

public Contact(Context context, String nom, String phoneNo,Groupe groupe) {
    super(context);
    this.nom = nom;
    this.phoneNo=phoneNo;
    this.groupe=groupe;
}

public Contact(String nom, String phoneNo,Groupe groupe) {
    super(null);
    this.nom = nom;
    this.phoneNo=phoneNo;
    this.groupe=groupe;
}

public String getNom() {
    return nom;
}

public void setNom(String nom) {
    this.nom = nom;
}



public String getPhoneNo() {
    return phoneNo;
}

public void setPhoneNo(String phoneNo) {
    this.phoneNo = phoneNo;
}

public Groupe getGroupe() {
    return groupe;
}

public void setGroupe(Groupe groupe) {
    this.groupe = groupe;
}

@Override
public String toString() {
    return  nom + "\r\n" + phoneNo + " "+id ;
}

public boolean isSelected() {
      return selected;
}

public void setSelected(boolean selected) {
      this.selected = selected;
}

private ListView listview;


protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.contactbase);


    listview = (ListView) findViewById(android.R.id.list);
    getListView().setOnCreateContextMenuListener(this);

    @SuppressWarnings("unchecked")
    List<Contact> contacts = Select.from(Contact.class).list();
    ContactAdapter3 objAdapter = new ContactAdapter3(CheckActivity.this, R.layout.contact_check, contacts);
    listview.setAdapter(objAdapter);
}

public void MyHandler(View v) {
    CheckBox cb = (CheckBox) v;

    if (cb.isChecked()) {
        CharSequence nom = cb.getText();
        String nom1= nom.toString();
        List<Contact> con = Contact.find(Contact.class, "nom= ?", nom1);
        Contact coo = con.get(0);
        Contact cc=Contact.findById(Contact.class,coo.getId() );
        System.out.println("la position est : "+coo.getId());
        cc.setSelected(true);


    } else {
        CharSequence nom = cb.getText();
        String nom1= nom.toString();
        List<Contact> con = Contact.find(Contact.class, "nom= ?", nom1);
        Contact coo = con.get(0);
        Contact cc=Contact.findById(Contact.class,coo.getId() );
        System.out.println("la position est : "+coo.getId());

        cc.setSelected(false);
    }
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    menu.add( 1 , 1 , 3 , "Enregistrer");
    return super.onCreateOptionsMenu(menu);
}


@Override
public boolean onOptionsItemSelected(MenuItem item) {

    Intent i = new Intent (getApplicationContext(), GroupeListActivity.class);
    startActivity(i);
    return super.onOptionsItemSelected(item);
}