How to run an application in multiple threads?

I'm developing an application with interface made by Swing. The purpose of the application is to simulate a computer network in which I will monitor using the InetAddress implementation. Well, I created my interface, where the user registers the machine name and its IP, as shown below:

Theusercanregisterasmanymachinesashewants,allthisinformationisalreadybeingsavedintheTXTfile.AspermyclassMonitor:

publicclassMonitorextendsjavax.swing.JFrame{privateArrayList<Computador>computadores;//publicArrayList<Computador>getComputadores(){//returncomputadores;//}////publicvoidsetComputadores(ArrayList<Computador>computadores){//this.computadores=computadores;//}/***CreatesnewformNovoJFrame*/publicMonitor(){initComponents();try{Scanners=newScanner(newFileInputStream("registro.txt"));
        while (s.hasNext()) {
            String var = s.nextLine();
            if (var.equals(" ")) {
                String nome = s.nextLine();
                String ip = s.nextLine();
                computadores.add(new Computador(nome, ip));
            }
        }
        s.close();
    } catch (FileNotFoundException e) {

    };
}


private void btnGravarMouseClicked(java.awt.event.MouseEvent evt) {                                       
    File arq = new File("registro.txt");
    btnGravar.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            // Condição, verifica se os campo estão vazios.
            if (campoNome.getText().equals("")) {

                JOptionPane.showMessageDialog(null,
                        "Adicione um nome ao computador!");
                campoNome.requestFocus();
            } else if (campoIP.getText().equals("")) {
                JOptionPane.showMessageDialog(null,
                        "Adicione um IP!");
                // Fornece o foco ao cursor da caixa de Texto
                campoIP.requestFocus();
            } else {
                // Tratamento de Erros.
                try {
                    FileWriter fw = new FileWriter(arq, true);
                    try (BufferedWriter bw = new BufferedWriter(fw)) {
                        bw.write(campoNome.getText() + " ");
                        bw.write(campoIP.getText() + "\n");
                        bw.flush();
                        bw.close();
                    }
                    campoNome.setText("");
                    campoIP.setText("");
                    // Exibe caixa de Dialogo.
                    JOptionPane.showMessageDialog(null,
                            "Arquivo Gravado com Sucesso!");

                } catch (IOException Erro) {
                    JOptionPane.showMessageDialog(null,
                            "Erro ao Gravar no Arquivo" + Erro);
                }
            }
        }
    });

}                                      

private void btnAbrirMouseClicked(java.awt.event.MouseEvent evt) {                                      
    btnAbrir.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            Computador cp = new Computador(null, null);
            cp.run();

        }
    });
}                                     

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new Monitor().setVisible(true);
        }
    });
}


}

In this same class it opens the TXT file and saves the information in ArrayList<Computador> computadores;

Now that's where my problem when I click on the CREATE , the application is to get all of the IPs that are in the ArrayList and play in the thread, however it does not enter the loop who will do this. I put a test out of the loop and it only runs that test.

Below is the class responsible for picking up information from the array and playing in the thread:

Computer class

public class Computador extends javax.swing.JPanel implements Runnable {

private String nome;
private String ip;
//private boolean online;

private Thread processo;

/**
 * Creates new form Computador
 */
public Computador(String n, String i) {

    initComponents();

    nome = n;
    ip = i;
    //online = s;

    CampoNome.setText(n);
    CampoIP.setText(i);
    /*if(online) {
        CampoStatus.setText("Online");
    }else{
        CampoStatus.setText("Offline");
    }*/

    processo = new Thread(this);
    processo.start();
}

@Override
public void run() {

    while (true) {
        ArrayList<Computador> computadores = new ArrayList();

        for (int i = 0; i < computadores.size(); i++) {
            String addr = computadores.get(i).ip;

            try {
                if (InetAddress.getByName(addr).isReachable(3000)) {
                    String nome = InetAddress.getByName(addr).getHostName();
                    System.out.println("Host " + nome + " (" + addr + ") ativo!");
                } else {
                    System.out.println("Host " + addr + " inativo!");
                }
            } catch (UnknownHostException ex) {
                Logger.getLogger(Computador.class.getName()).log(Level.SEVERE, null, ex);
            } catch (IOException ex) {
                Logger.getLogger(Computador.class.getName()).log(Level.SEVERE, null, ex);
            }

        }
        System.out.println("Testando");
        try {
            processo.sleep(5000);
        } catch (InterruptedException ex) {
            Logger.getLogger(Computador.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

Here is the output on the console, (so far I have not played the information in the interface).

For each IP that it gets from ArrayList , it will run a computer on a thread and display on the interface the computer icon, the name of that machine, as well as its IP and status.

Can anyone help me with the development of this application?