Swing : Write in a JLabel

Question

I want to open a JFrame that has a jpanel with two jlabel, with a method that loops and rewrites those labels. Of course in the loop I have a thread.sleep, BUT I can't figure it out, my thread begins to run 1.. 2.. 3.. and when this finished the JFrame opens.

Here is my code I have wrote so far:

    FrmPruebaPlanillon vtnPruebaPlanillon = new FrmPruebaPlanillon();
    vtnPruebaPlanillon.setVisible(true);

    boolean infinito = true;
    while(infinito)//todo ver con cuidado
    {       
        //enviamos los comando por fila para podrer rellenar los datos del 
        //taximetro con el boleto generado
        System.out.println(FrmPrincipal.linea()+"Inició la prueba "+        (contadorDePrueba+1));
        //pp.getLblNEnvio().setText((contadorDePrueba+1)+"");
        vtnPruebaPlanillon.getLblNEnvio().setText((contadorDePrueba+1)+"");
        vtnPruebaPlanillon.getLblDatoEnviado().setText(fila[contadorDePrueba]);
        //pp.getLblDatoEnviado().setText(fila[contadorDePrueba]);



       //#######################################################################3
        pruebaPorTabla(tipoPrueba, datosCsv);
        //pruebaPorFila(tipoPrueba, fila[contadorDePrueba]); 
        //vtnFrmBoleto.setParametrosPrueba(tipoPrueba, tblPrueba, numeroPrueba,  taximetro, empresa);
        //pone un numero de prueba en la ventana boleto
        if(contadorDePrueba == 0)
        {
            //vtnFrmBoleto.getLblNprueba().setText((String) tblPrueba.getModel().getValueAt(0, 0));
        }           
        //vtnFrmBoleto.setVisible(true);
        contadorDePrueba++;
        if(contadorDePrueba==dataTabla.length-1)
        {
            System.out.println("numero de lineas enviadas"+contadorDePrueba);
            infinito=false;
        }

    }      

Answer 1

Of course, calling Thread.sleep(); on EDT causes such an unpredictable behaviour as I pointed in my commnet. Use proper component instead. In this case, swing Timer. Here is a small demo for you:

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

public class RepaintDemo {

    JFrame frame = new JFrame("Repaint demo");
    JLabel labelFirst = new JLabel("First label");
    JLabel labelSecond = new JLabel("Second label");
    JLabel[] labels = { labelFirst, labelSecond };
    JPanel panel = new JPanel();
    Timer timer;
    int i = 0;

    public RepaintDemo() {
        // Wait for 3 seconds and then add label
        timer = new Timer(3000, new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                panel.add(labels[i]);
                panel.repaint();
                panel.revalidate();
                i++;
                if (i == labels.length) {
                    timer.stop();
                }
            }
        });
        // Adds next label after every 3 seconds
        timer.setDelay(3000);
        timer.setRepeats(true);
        timer.start();

        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.add(panel);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new RepaintDemo();
            }
        });
    }

}

As you can see, JFrame will appear upon startup. After 3 seconds, first label will appear. And after another 3 seconds, second label will appear too.