Problem with the t.start()

package fr.HypeStoner.azuria.launcher;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;

import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import fr.theshark34.supdate.*;

import fr.theshark34.openauth.AuthenticationException;
import static fr.theshark34.swinger.Swinger.*;
import fr.theshark34.openlauncherlib.launcher.util.UsernameSaver;
import fr.theshark34.swinger.Swinger;
import fr.theshark34.swinger.event.SwingerEvent;
import fr.theshark34.swinger.event.SwingerEventListener;
import fr.theshark34.swinger.textured.STexturedButton;

@SuppressWarnings("serial")
public class LauncherPanel extends JPanel implements SwingerEventListener {

    private Image background = Swinger.getResource("background.png");

    private UsernameSaver saver = new UsernameSaver(Launcher.AHT_INFOS);

    private JTextField usernameField = new JTextField(saver.getUsername(""));
    private JPasswordField passwordField = new JPasswordField();

    private STexturedButton playButton = new STexturedButton(getResource("play.png"));
    private STexturedButton closeButton = new STexturedButton(getResource("close.png"));
    private STexturedButton reductButton = new STexturedButton(getResource("reduct.png"));


    public LauncherPanel() {
        this.setLayout(null);


        usernameField.setForeground(Color.WHITE);
        usernameField.setFont(usernameField.getFont().deriveFont(20F));
        usernameField.setCaretColor(Color.WHITE);
        usernameField.setOpaque(false);
        usernameField.setBorder(null);
        usernameField.setBounds(85, 320, 266, 39 );
        this.add(usernameField);

        passwordField.setForeground(Color.WHITE);
        passwordField.setFont(passwordField.getFont().deriveFont(20F));
        passwordField.setCaretColor(Color.WHITE);
        passwordField.setOpaque(false);
        passwordField.setBorder(null);
        passwordField.setBounds(82, 429, 266, 39 );
        this.add(passwordField);

        playButton.setBounds(650, 453);
        playButton.addEventListener(this);
        this.add(playButton);

        closeButton.setBounds(900, 20);
        closeButton.addEventListener(this);
        this.add(closeButton);

        reductButton.setBounds(825, 20);
        reductButton.addEventListener(this);
        this.add(reductButton);

    }



    @Override
    public void onEvent (SwingerEvent event) {
        if(event.getSource() == playButton)  {
            setFieldsEnabled(false);

            if(usernameField.getText().replaceAll(" ",  "").length() == 0 || passwordField.getText().length() == 0 ) {
                JOptionPane.showMessageDialog(this, "Erreur ! Veuillez entrer un pseudonyme ainsi qu'un mot de passe valide, merci !", "Erreur", JOptionPane.ERROR_MESSAGE );
                setFieldsEnabled(true);
                return;
            }

            Thread t = new Thread() {
                @Override
                public void run() {


            }
            t.start();
    }   else if(event.getSource() == closeButton)
                System.exit(0);
        else if(event.getSource() == reductButton)
            LauncherFrame.getInstance().setState(JFrame.ICONIFIED);




}




    @Override
    public void paintComponent(Graphics graphics) {
        super.paintComponent(graphics);
        drawFullsizedImage(graphics, this, background);
    }


    private void setFieldsEnabled(boolean enabled) {
        usernameField.setEnabled(enabled);
        passwordField.setEnabled(enabled);
        playButton.setEnabled(enabled);
    }

}