Encerramento do formulário com jProgressBar

public class Load extends javax.swing.JFrame {
    public Load() {
        initComponents();     
        new Thread(){
            @Override
            public void run(){               
                for (int i = 0;i <=100; i++){                                            
                    try{
                        sleep(20);
                        jProgressBar1.setValue(i); 
                        
                    }
                    catch(InterruptedException ex){                       
                       }               
                }              
               Principal p = new Principal();//Carrega o formlário Principal
               p.setVisible(true);            
            }                        
        }               
        .start();
    }   
    @Override
    public void dispose() {
        super.dispose(); //To change body of generated methods, choose Tools | Templates.
    }    
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jProgressBar1 = new javax.swing.JProgressBar();
        jLabel1 = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Carregando...");
        setResizable(false);

        jProgressBar1.setBackground(new java.awt.Color(255, 102, 51));
        jProgressBar1.setFont(new java.awt.Font("Tahoma", 2, 18)); // NOI18N
        jProgressBar1.setForeground(new java.awt.Color(255, 153, 51));
        jProgressBar1.setStringPainted(true);

        jLabel1.setFont(new java.awt.Font("Tahoma", 0, 24)); // NOI18N
        jLabel1.setForeground(new java.awt.Color(255, 153, 51));
        jLabel1.setText("CARREGANDO...");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jProgressBar1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addContainerGap())
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(228, Short.MAX_VALUE)
                .addComponent(jLabel1)
                .addGap(225, 225, 225))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(26, Short.MAX_VALUE)
                .addComponent(jLabel1)
                .addGap(18, 18, 18)
                .addComponent(jProgressBar1, javax.swing.GroupLayout.PREFERRED_SIZE, 38, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(33, 33, 33))
        );

        pack();
        setLocationRelativeTo(null);
    }// </editor-fold>                        

    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(Load.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Load.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Load.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Load.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Load().setVisible(true);                                                      
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JLabel jLabel1;
    private javax.swing.JProgressBar jProgressBar1;
    // End of variables declaration                   
}