public static void main(String args[]) {
        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(ApplicationInvoices.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(ApplicationInvoices.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(ApplicationInvoices.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(ApplicationInvoices.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

	
	File guard = new File(".guard");
	if(guard.exists()){
	    JOptionPane.showMessageDialog(null, "Er is al een andere instantie van het programma actief.", "Melding", JOptionPane.INFORMATION_MESSAGE);
	    System.exit(0);
	} else {
	    try {
		guard.createNewFile();
		guard.deleteOnExit();
	    } catch (IOException ex) {
		Logger.getLogger(ApplicationInvoices.class.getName()).log(Level.SEVERE, null, ex);
	    }
	}
	
        database.Database.driver();

        UIManager.getLookAndFeelDefaults().put("defaultFont", new Font("Arial", Font.PLAIN, Utilities.fontSize()));

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

        System.out.println(Configuration.center().getDB_URL());
    }