`HTTP – 500 error

javax.servlet.ServletException:
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)

(root cause)

java.lang.NoClassDefFoundError: Could not initialize class org.zerock.w2.dao.ConnectionUtil
org.zerock.w2.dao.TodoDAO.selectAll(TodoDAO.java:65)

org.zerock.w2.service.TodoService.listAll(TodoService.java:34)
org.zerock.w2.controller.TodoListController.doGet(TodoListController.java:29)
javax.servlet.http.HttpServlet.service(HttpServlet.java:529)

javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)

`

not typing error……….

cant progress………..

im dying………

tell me cases plz…………

thx……………….