1. Difference between Array List and Vector, Hash Map and Hash Table, Collection and Collections

2. Differnce between Thread and Process

3. Advanced features in JDK 6 and Jdk5

4. Explain System.out.println()

These are some sample core JAVA questions.

1. What is the default scope of form bean when scope is not specified in Struts-config.xml

2. How can you configure more than one struts-config.xml in your applicaiton?

3. Disadavtages with Dyna Action forms when compared to Action Forms in Struts

4. Difference between MVC1 and MVC2 frameworks

5. Difference between Action Errors and Action Messages

6. Components of Web.xml, struts-config.xml and ejb-jar.xml

7. Difference between Struts 1.0 and Struts 1.1

8. Call back methods of Entity beans

9. various types of Action Classes

10. Types of Action Forms

11. Difference between Dispatch Action and Look up dispatch Action

12. Usage of Validator-rules.xml and validation.xml in validation framework

13. How to call ejbs from Struts

14. Usage of Aciton Servet and methods of Action class in Struts

15. Diffence between Validator form and Dyna validator form