Phonebook class

package cartedetelefon;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.table.AbstractTableModel;

public class CarteDeTelefon extends AbstractTableModel implements Serializable {

    private static List<Abonat> listaContacte = new ArrayList<Abonat>();
    public static File f;
    private static final long serialVersionUID = 1L;
    private static final Logger fLogger = Logger.getLogger(CarteDeTelefon.class.getPackage().getName());

    /**
     * @return the listaContacte
     */
    public static List<Abonat> getListaContacte() {
        return listaContacte;
    }

    /**
     * @param aListaContacte the listaContacte to set
     */
    public static void setListaContacte(List<Abonat> aListaContacte) {
        listaContacte = aListaContacte;
    }

    private final String[] numeColoane = {
        "Nume",
        "Prenume",
        "CNP",
        "Numar telefon"
    };

    // adauga contact in lista
    public void adaugareContact(String nume, String prenume, String cnp, String tel) {

        try {
            try {
                Long s = Long.valueOf(tel);
                getListaContacte().add(new Abonat(nume, prenume, cnp, new NrTel(s)));

                fireTableDataChanged();
            } catch (NumberFormatException numberFormatException) {
            }
        } catch (Exception e) {
        }

    }

    public void modificareContact(Abonat a, int row) {
        try {
            if (listaContacte.size() >= 0) {
                listaContacte.set(row, a);
            }
            fireTableDataChanged();
        } catch (Exception e) {
        }
    }

    public void stergeContact(int row) {

        try {
            try {
                getListaContacte().remove(row);
                fireTableDataChanged();
            } catch (Exception e) {
            }
        } catch (Exception e) {
        }
    }

    public List<Abonat> cautareContact(String str) {
        List<Abonat> returnareContacte = new ArrayList<Abonat>();
        getListaContacte().stream().filter((abonat) -> (abonat.getPrenume().contains(str) || abonat.getNume().contains(str))).forEach((abonat) -> {
            returnareContacte.add(abonat);
        });
        return returnareContacte;
    }

    @Override
    public int getRowCount() {
        if (getListaContacte().size() <= 0) {
            return 0;
        } else {
            return getListaContacte().size();
        }

    }

    @Override
    public int getColumnCount() {
        return numeColoane.length;
    }

    @Override
    public String getColumnName(int col) {
        return numeColoane[col];
    }

    @Override
    public Object getValueAt(int row, int col) {
        if (col == 0) {
            return getListaContacte().get(row).getNume();
        } else if (col == 1) {
            return getListaContacte().get(row).getPrenume();
        } else if (col == 2) {
            return getListaContacte().get(row).getCNP();
        } else if (col == 3) {
            return getListaContacte().get(row).getNrTel();
        }

        return "Eroare";
    }

    @Override
    public void setValueAt(Object aValue, int rowIndex, int colIndex) {

        Abonat abonat = getListaContacte().get(rowIndex);
        switch (colIndex) {
            case 2:
                abonat.setCNP((String) aValue);
                break;
            case 3:
                abonat.setNrTel((NrTel) aValue);
                break;
        }
        fireTableRowsUpdated(rowIndex, rowIndex);

    }

    @Override
    public boolean isCellEditable(int row, int colNum) {
        switch (colNum) {
            case 2:
                return false;
            default:
                return true;
        }
    }

    public void salvareContacte() throws FileNotFoundException, IOException {

        try (
                OutputStream file = new FileOutputStream("contacts.txt");
                OutputStream buffer = new BufferedOutputStream(file);
                ObjectOutput output = new ObjectOutputStream(buffer);) {
            output.writeObject(listaContacte);
        } catch (IOException ex) {
            fLogger.log(Level.SEVERE, "Fisierul nu a putut fi salvat.", ex);
        }

    }

    public void incarcareContacte() throws IOException, ClassNotFoundException {

        try (
                InputStream file = new FileInputStream("contacts.txt");
                InputStream buffer = new BufferedInputStream(file);
                ObjectInput input = new ObjectInputStream(buffer);) {

            @SuppressWarnings("unchecked")
            List<Abonat> recoveredContacts = (List<Abonat>) input.readObject();

            listaContacte = recoveredContacts;
            fireTableDataChanged();

        } catch (ClassNotFoundException | IOException ex) {
            fLogger.log(Level.SEVERE, "Fisierul nu este valid", ex);
        }
    }

}