Dynamically update (refresh) a JDialog (swing)

The best I got was that. I do not know what he should do exactly when reloading the screen, so I put a System.out.println there to demonstrate that the method was called. Whenever I select in JComboBox a name equal to JTextField , this function is called and the text is written in the console.

Here is the code:

import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComboBox;
import javax.swing.JDialog;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class AltCadastroUsuario extends JDialog {
    private final JPanel contentPanel;

    protected String nome;

    public static void main(String[] args) {
        EventQueue.invokeLater(AltCadastroUsuario::iniciar);
    }

    private static void iniciar() {
        try {
            AltCadastroUsuario dialog = new AltCadastroUsuario();
            dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            dialog.setSize(400, 200);
            dialog.setVisible(true);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public AltCadastroUsuario() {
        contentPanel = new JPanel();
        this.add(contentPanel);
        JTextField txtLogin = new JTextField();
        txtLogin.setText("Teste");
        contentPanel.add(txtLogin);

        JComboBox<String> jComBox_NomeUsuar = new JComboBox<>();
        jComBox_NomeUsuar.addItem("Pedro");
        jComBox_NomeUsuar.addItem("Carlos");
        contentPanel.add(jComBox_NomeUsuar);

        jComBox_NomeUsuar.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent arg0) {
                String selected = (String) jComBox_NomeUsuar.getSelectedItem();
                if (selected.equalsIgnoreCase(txtLogin.getText())) {
                    nome = selected;
                    recarregarTela();
                }
            }
        });
    }

    protected void recarregarTela() {
        System.out.println("Recarregando");
        //altCadastroUsuario.this.removeAll();
        AltCadastroUsuario.this.repaint();
        AltCadastroUsuario.this.revalidate();
        //contentPanel.repaint();
        //contentPanel.revalidate();
    }
}

In your code there were the following problems:

• You were using protect instead of protected , which caused a compile error ( as reviewed by Bruno César ).
• Some casts were missing when using the getSelectedItem() method of JComboBox . This also caused a compilation error.
• You did not give the whole class, which obviously makes your code non-compilable and leaves your question harder to answer. It took me some time to realize that altCadastroUsuario was the class name. However, I should not have to guess this by myself. In addition, class names should start with uppercase letters. I also had to deduce that altCadastroUsuario is subclass of JDialog .
• Do not access Swing outside the AWT event thread.
• Set a default window size before showing it, so there will not be a window of minimum size that I'm required to resize to use.
• The nome field contains null when the class constructor is started. As a result, JTextField was of such a ridiculously small size that it was not usable.
• You added JComboBox and JTextField to JPanel , but did not add JPanel to the screen. The result is a blank canvas!
• It pays to put a legal layout on your JPanel . As it is, it's even hard to use.
• As I mentioned before, I do not know what else should happen in recarregarTela . I put there System.out.println just to prove that it is called when it should actually be called.

• If you want to make it simpler, if you are using Java 8 or higher, use a lambda:

      jComBox_NomeUsuar.addActionListener(event -> {
          String selected = (String) jComBox_NomeUsuar.getSelectedItem();
          if (selected.equalsIgnoreCase(txtLogin.getText())) {
              nome = selected;
              recarregarTela();
          }
      });
  

The question has been edited. Now my suggestion is to change this excerpt:

                for (cadastroBase load : cadTotal){
                    if (selected.equalsIgnoreCase(load.nomes)){
                        valCadBas.setLogin(load.login);
                        valCadBas.setPass(load.pass);
                        recarregarTela();
                    }
                }

So:

                for (cadastroBase load : cadTotal) {
                    if (selected.equalsIgnoreCase(load.nomes)) {
                        valCadBas.setLogin(load.login);
                        valCadBas.setPass(load.pass);
                        txtLogin.setText(load.login);
                        passSenha.setText(load.pass); // Isso só se você achar que faz sentido colocar a senha.
                        break;
                    }
                }

And with that, the recarregarTela() method ceases to exist.