Событие в jcalendar / jdatechooser

Question

Я делаю проект на NetBeans, в котором мне нужно выбрать дату в jcalendar / jdatechooser, и когда дата выбрана, затем поместить эту дату в запрос MySQL.Итак, какое событие может быть полезным, в котором я должен разместить свой код.Я уже пытался поместить его в AncestorAdded, Изменение свойства и т. Д. Мой код:

float tsale = 0;
Connection con = getConnection();
PreparedStatement ps;
try {
ps = con.prepareStatement("select sum(amount) from sales where add_date = 
?;");
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
String addDate;
addDate = dateFormat.format( new java.sql.Date(datec.getDate().getTime()));
ps.setString(1, addDate);
ResultSet rs = ps.executeQuery();
if (rs.next()) {
    tsale = (float) rs.getLong(1);
}

} catch (SQLException ex) {
    Logger.getLogger(specSale.class.getName()).log(Level.SEVERE, null, ex);
}
salel.setText(String.valueOf(tsale));

Ошибка:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at specSale.datecAncestorAdded(specSale.java:174)
at specSale.access$100(specSale.java:21)
at specSale$2.ancestorAdded(specSale.java:80)
at javax.swing.AncestorNotifier.fireAncestorAdded(AncestorNotifier.java:86)
at javax.swing.AncestorNotifier.componentShown(AncestorNotifier.java:193)
at java.awt.Component.processComponentEvent(Component.java:6365)
at java.awt.Component.processEvent(Component.java:6313)
at java.awt.Container.processEvent(Container.java:2236)
at java.awt.Window.processEvent(Window.java:2025)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2294)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)