where is created java files aftering running JSP in WSAD

I got the following error after I ran a jsp using Websphere Studio Application Developer under the test enviorment:
http://localhost:8080/test/Modify.jsp
Error Message:
Error Code: 500
Target Servlet: null
Error Stack:
java.lang.NullPointerException
at ad.reports.Modify_jsp_2._jspService(Modify_jsp_2.java:159)
I want to take a look at the created java file Modify_jsp_2.java but could not find it. Any one has any idea how to locate the java file created from JSP under WSAD? thanks!